2000 Audi TT

2000-2004 ENGINE PERFORMANCE Multiport Fuel Injector (MFI): 1.8L Turbo, AMU & BEA - TT

2000-2004 ENGINE PERFORMANCE

Multiport Fuel Injector (MFI): 1.8L Turbo, AMU & BEA - TT

MULTIPORT FUEL INJECTION

MOTRONIC INJECTION SYSTEM, SERVICING

Safety precautions

WARNING: To reduce the danger of personal injury and/or damage to the fuel
injection and ignition system, always observe the following:

z Only disconnect and reconnect wires for injection and ignition

system, including test leads, when ignition is turned off.
z If engine is to be cranked at starting RPM without starting (for
example, for compression testing), disconnect connector from
ignition coils and from fuel injectors.
z It is possible that the control module will recognize a malfunction
and store a DTC during some tests. After completing all tests and
repairs, DTC memory should therefore be checked and erased if
necessary. After erasing DTC memory the readiness code must be
regenerated. See READINESS CODE, GENERATING .
z Always switch ignition off before cleaning engine.
z The battery should only be disconnected and reconnected when the
ignition is turned off, since otherwise the Engine Control Module
(ECM) can be damaged.

If special testing equipment is required during test drive, observe the following:

WARNING: z To reduce the danger of accident, always proceed as follows during

road tests:

Audi TT Coupe: Use only the VAS5051 or VAG1551 to read

measuring value blocks. Always secure the tester to the rear seat
and operate it from there by a second technician. Due to size
constraints, the passenger seat should be adjusted as far forward as
possible and it's seatback should be adjusted to the most forward
engaged position using the hand wheel. Do not use the seatback
release lever for this.

Audi TT Roadster: Use only the VAG1552 with deactivated passenger side
airbag in the Audi TT Roadster. Deactivate passenger-side airbag using

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 2000 Audi TT
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key switch in the glove compartment. See AIR BAG RESTRAINT

SYSTEMS . Re-activate passenger-side airbag after completing work.

WARNING: Fuel system is under pressure! Place a cloth around connection point
before opening system. Then release pressure by carefully loosening
connection point.

Rules of cleanliness

When working on the fuel supply or fuel injection systems, the following "6 rules of cleanliness" should be
carefully observed:

z Thoroughly clean all connections and the surrounding area before disconnecting.
z Place parts that have been removed on a clean surface and cover. Use lint-free cloths only!
z Carefully cover opened components or seal them if repairs are not carried out immediately.
z Only install clean components: Only unpack replacement parts immediately prior to installation. Do not
use parts that have been stored loose (in tool boxes etc.)
z When the system is open: Do not work with compressed air if it can be avoided. Do not move vehicle
unless absolutely necessary.
z Disconnected electrical harness connectors: Protect from dirt and moisture. Be sure harness connector is
dry before connecting.

Technical data

TECHNICAL DATA
AMU/BEA (1.8L/V/Turbo/165 kW-
Engine identification engine)
Idle speed 700 to 820 RPM
Engine speed cannot be adjusted, it is regulated by idle
stabilization
Engine speed (RPM) limitation 6800 RPM
via fuel injector shut-off
Fuel pressure at idle speed Vacuum hose connected about 2.5 bar positive pressure
Vacuum hose disconnected about 3.0 bar positive pressure
Residual pressure after 10 min. at least 1.5 bar positive pressure
Fuel injectors Injection stream same for all injectors
Injection quantity (30 s) 179 +/- 14 ml
Resistance 12 to 13 ohm
(room temperature)

Component locations, overview

NOTE: The following list refers to items in Fig. 1 .

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1. - Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- with Oxygen Sensor
(O2S) Heater 1 (behind Three Way Catalytic Converter (TWC) - Z29 - .
z Installation location. See COMPONENT LOCATION: OXYGEN SENSOR BEHIND
CATALYTIC CONVERTER WITH SHIELDED ELECTRICAL CONNECTOR .
z Oxygen sensor and oxygen sensor controller behind catalytic converter, testing. See OXYGEN
SENSOR (O2S) AND OXYGEN SENSOR CONTROL BEFORE THREE WAY
CATALYTIC CONVERTER (TWC), CHECKING .
z Oxygen sensor heater for oxygen sensor behind catalytic converter, testing. See OXYGEN
SENSOR (O2S) HEATING - Z29- FOR OXYGEN SENSOR AFTER THREE WAY
CATALYTIC CONVERTER (TWC), CHECKING .
z Removing and installing. See OXYGEN SENSOR (O2S), REMOVING AND INSTALLING .

2. - 4-pin harness connector

z For Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC)- and Oxygen Sensor
(O2S) Heater 1 -Z19- (brown)
z Installation location. See MOTRONIC ENGINE CONTROL MODULE (ECM) POWER
SUPPLY RELAY -J271- .
3. - Heated Oxygen Sensor (HO2S) -G39- with Oxygen Sensor (O2S) Heater -Z19-
z Constant oxygen sensor

z Oxygen sensor and oxygen sensor controller before catalytic converter, testing. See OXYGEN
SENSOR (O2S) SYSTEM, CHECKING .
z Oxygen sensor aging before catalytic converter, checking. See OXYGEN SENSOR (O2S)
AGING (HO2S BEFORE TWC), CHECKING .
z Oxygen sensor heater for oxygen sensor before catalytic converter, testing. See OXYGEN
SENSOR (O2S) HEATING - Z19- FOR OXYGEN SENSOR BEFORE THREE WAY
CATALYTIC CONVERTER (TWC), CHECKING .
z Removing and installing. See OXYGEN SENSOR (O2S), REMOVING AND INSTALLING .

4. - 4-pin harness connector

z Heated Oxygen Sensor (HO2S) -G39- and Oxygen Sensor (O2S) Heater 1 -Z19- (black)

5. - Motronic Engine Control Module (ECM) -J220-

z Voltage supply for ECM, checking. See VOLTAGE SUPPLY FOR ENGINE CONTROL
MODULE (ECM), CHECKING .
z See PROCEDURE AFTER INTERRUPTION OF VOLTAGE SUPPLY .

z Replacing. See ENGINE CONTROL MODULE (ECM) (WITHOUT METAL ANTI-THEFT

HOUSING), REPLACING .
6. - Ignition coils, -N128-, -N158-, -N163-
z Cylinder 1 -N-

z Cylinder 2 -N128-

z Cylinder 3 -N158-

z Cylinder 4 -N163-

z Checking. See IGNITION COILS WITH POWER OUTPUT STAGES, CHECKING .

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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injector (MFI): 1.8L Turbo, AMU & BEA - TT

7. - Recirculating valve for turbocharger -N249-

z Installation location. See INSTALLATION POSITION: RECIRCULATING VALVE FOR
TURBOCHARGER -N249- .
z Checking:

See CHARGE AIR SYSTEM WITH TURBOCHARGER .

8. - Combination valve for secondary air injection (AIR)

z Checking, removing and installing:

See SECONDARY AIR SYSTEM COMPONENTS, REMOVING AND INSTALLING .

9. - Throttle Position (TP) sensor -G79- and sender 2 for accelerator pedal position - G185 -
z Component location. See INSTALLATION POSITION: THROTTLE POSITION (TP)
SENSOR -G79- AND SENDER 2 FOR ACCELERATOR PEDAL POSITION -G185- .
z Checking. See THROTTLE POSITION (TP) SENSOR AND SENDER -2- FOR
ACCELERATOR PEDAL POSITION, CHECKING .
10. - Brake light switch -F- and brake pedal switch -F47 -
z Component location. See BRAKE LIGHT SWITCH -F- AND BRAKE PEDAL SWITCH -
F47- .
11. - Clutch vacuum vent valve switch -F36-
z Component location. See CLUTCH VACUUM VENT VALVE SWITCH -F36- .

12. - Instrument cluster

z with Electronic Power Control (EPC) Warning Lamp -K85-

z with Malfunction Indicator Lamp (MIL) -K85-

13. - Motronic Engine Control Module (ECM) Power Supply Relay -J271-
z Installation location. See MOTRONIC ENGINE CONTROL MODULE (ECM) POWER
SUPPLY RELAY -J271- .
z Checking. See MOTRONIC ENGINE CONTROL MODULE (ECM) POWER SUPPLY
RELAY -J271-, CHECKING .
14. - Mass Air Flow (MAF) sensor -G70-
z Checking. See MASS AIR FLOW (MAF) SENSOR - G70-, CHECKING .

15. - Wastegate bypass regulator valve -N75-

z Checking:

See CHARGE AIR SYSTEM WITH TURBOCHARGER

16. - Engine Coolant Temperature (ECT) sensor -G62-

z Checking. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR -G62-, CHECKING .

z Relieve pressure from cooling system before removing

17. - Valve 1 for camshaft adjustment -N205-

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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injector (MFI): 1.8L Turbo, AMU & BEA - TT

See VALVES, SERVICING .

18. - Fuel pressure regulator

z checking. See SYSTEM PRESSURE, FUEL PRESSURE REGULATOR AND RESIDUAL
PRESSURE, CHECKING .
19. - Knock Sensor (KS) 2 -G66-
20. - Charge air pressure sensor - G31-
z Screwed into upper portion of charge air intercooler

z Checking:

See CHARGE AIR PRESSURE SENSOR -G31-, TESTING .

21. - Engine Speed (RPM) sensor -G28-

z Checking. See ENGINE SPEED (RPM) SENSOR - G28-, CHECKING .

22. - Throttle valve control module -J338-

z With throttle drive (power accelerator actuation) - G186 -, angle sensor -1- for throttle drive (power
accelerator actuation) - G187 -, and angle sensor 2 for throttle drive (power accelerator actuation) -
G188 -
z Checking. See THROTTLE VALVE CONTROL MODULE -J338-, CHECKING .

z Perform adaptation after replacing. See THROTTLE VALVE CONTROL MODULE -J338-,
ADAPTING .
23. - Intake Air Temperature (IAT) sensor -G42-
z Checking. See INTAKE AIR TEMPERATURE (IAT) SENSOR -G42-, CHECKING .

24. - 3-pin harness connector

z For engine speed (RPM) sensor -G28-

25. - Sensor 1 for exhaust temperature -G235-

z Temperature sensor located in turbocharger

26. - Fuel Injectors

z Cylinder 1 Fuel Injector - N30-

z Cylinder 2 Fuel Injector - N31-

z Cylinder 3 Fuel Injector - N32-

z Cylinder 4 Fuel Injector - N33-

z Checking. See FUEL INJECTORS, CHECKING .

z Removing and installing. See FUEL INJECTORS, REMOVING AND INSTALLING .

27. - Secondary Air Injection (AIR) Pump Motor -V101-

z Checking:

See SECONDARY AIR SYSTEM COMPONENTS, REMOVING AND INSTALLING .

28. - Knock Sensor (KS) 1 -G61-

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29. - Pressure switch/power steering -F88-

z Component location. See INSTALLATION POSITION: PRESSURE SWITCH/POWER
STEERING -F88- .
30. - Camshaft Position (CMP) Sensor -G40-
z Checking. See CAMSHAFT POSITION (CMP) SENSOR -G40-, CHECKING .

31. - Evaporative Emission (EVAP) canister purge regulator valve -N80-

z Checking. See FUEL TANK VENTILATION SYSTEM, CHECKING .

Fig. 1: Identifying Motronic Injection System Components

Courtesy of AUDI OF AMERICA, INC.

Installation position: recirculating valve for turbocharger -N249-

z Installation location: On cylinder head cover

1. - To connection at intake manifold

2. - Vacuum reservoir
3. - To mechanical recirculating valve
4. - Recirculating valve for turbocharger -N249-

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Fig. 2: Identifying Recirculating Valve For Turbocharger -N249-

Courtesy of AUDI OF AMERICA, INC.

Installation position: Throttle Position (TP) sensor -G79- and sender 2 for accelerator pedal position -G185-

NOTE: In the illustration, a left hand drive vehicle is represented.

Fig. 3: Locating Throttle Position (TP) Sensor -G79- And Sender 2 For Accelerator Pedal Position -G185-
Courtesy of AUDI OF AMERICA, INC.

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Component location: Oxygen sensor behind catalytic converter with shielded electrical connector

1. - Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S)
Heater 1 (behind Three Way Catalytic Converter (TWC)) 1 -Z29-
2. - Protective shield for electrical connection

Fig. 4: Locating Oxygen Sensor Behind Catalytic Converter With Shielded Electrical Connector
Courtesy of AUDI OF AMERICA, INC.

The electrical connection for oxygen sensor and oxygen sensor heater is accessible by removing protective
shield from vehicle floor (arrow).

Motronic Engine Control Module (ECM) Power Supply Relay -J271-

z Under cover against left splash wall

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Fig. 5: Locating Motronic Engine Control Module (ECM) Power Supply Relay -J271-
Courtesy of AUDI OF AMERICA, INC.

NOTE: To remove protective cover on vehicles equipped with relay holder, detach from
splash wall and lower. If necessary, disconnect electrical connection at mass
air flow sensor.

Installation position: pressure switch/power steering -F88-

Fig. 6: Locating Pressure Switch/Power Steering -F88-

Courtesy of AUDI OF AMERICA, INC.
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Brake Light Switch -F- and Brake Pedal Switch -F47-

Fig. 7: Locating Brake Light Switch -F- And Brake Pedal Switch -F47-
Courtesy of AUDI OF AMERICA, INC.

Clutch Vacuum Vent Valve Switch -F36-

Fig. 8: Locating Clutch Vacuum Vent Valve Switch -F36-

Courtesy of AUDI OF AMERICA, INC.

Air cleaner housing, disassembling and assembling

NOTE: The following list refers to items in Fig. 9 .

1. - Seal
2. - Mass Air Flow (MAF) sensor -G70-
3. - Phillips-head screw
4. - Air duct
5. - 5-pin harness connector
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6. - Phillips-head screw
7. - Air cleaner housing, upper portion
8. - Air cleaner element
9. - Nut -10 Nm
10. - Air intake connection
11. - Air cleaner housing, lower portion
12. - Hex-bolt, -10 Nm

Fig. 9: Exploded View Of Air Cleaner Housing With MAF Sensor

Courtesy of AUDI OF AMERICA, INC.

Electrical testing using VAG1598/31 test box

NOTE: z VAG1598/31 test box is designed so that it can be simultaneously

connected to wiring harness at Engine Control Module (ECM) and also to
the ECM itself.
z This is advantageous because electronic engine control remains fully
functional (e.g. measurement of signals with engine running) when the test
box is attached.
z Relevant test procedures note if Engine Control Module (ECM) should also
be connected to the test box or not.
z If the Engine Control Module (ECM) is equipped with a metal anti-theft
housing (for theft prevention), the metal anti-theft housing must be
removed from the ECM to connect the test box. Procedure. See ENGINE
CONTROL MODULE (ECM) (WITH METAL ANTI-THEFT HOUSING),
REPLACING . After repairs are complete, the metal anti-theft housing must
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be reinstalled.
z Always use VAG1594A connector test kit to attach measurement devices
(e.g. VAG1527B voltage tester, VAG1526A multimeter etc.).

CAUTION: To reduce the danger of damage to electronic components, switch on

power to components before connecting test leads and observe test
requirements.

Special tools and equipment

z VAG1598/31

Fig. 10: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Procedure

z Switch ignition off.

z Remove the ECM. See ENGINE CONTROL MODULE (ECM) (WITHOUT METAL ANTI-
THEFT HOUSING), REPLACING .

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Fig. 11: Connecting VAG1598/31 Test Box To Connector Of Wiring Harness

Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1598/31 test box to connector of wiring harness. Ground (GND) clip (arrow) at test box
must be clipped to battery Ground. Relevant test procedures note if Engine Control Module (ECM)
should also be connected to the test box.
z Perform test as described in relevant repair sequence.

NOTE: Important notes after re-connecting Engine Control Module (ECM), see below.

z Perform adaptation procedure for Throttle Valve Control Module -J338-. See THROTTLE VALVE
CONTROL MODULE -J338-, ADAPTING .
z Check DTC memory and erase it if necessary. See CHECK DTC MEMORY (SCAN TOOL
FUNCTION 02) AND ERASE DTC MEMORY (SCAN TOOL FUNCTION 05) .
z Generate readiness code. See READINESS CODE, GENERATING .

Procedure after interruption of voltage supply,

NOTE: Important notes after re-connecting Engine Control Module (ECM):

z Perform the adaptation procedure for the Throttle Valve Control Module -
J338. See THROTTLE VALVE CONTROL MODULE -J338-, ADAPTING .
z Check DTC memory and erase it if necessary. See CHECK DTC MEMORY
(SCAN TOOL FUNCTION 02) AND ERASE DTC MEMORY (SCAN TOOL
FUNCTION 05) .
z Generate readiness code. See READINESS CODE, GENERATING .

Engine Control Module (ECM) (without metal anti-theft housing), replacing

Removing ECMs with metal anti-theft housing. See ENGINE CONTROL MODULE (ECM) (WITH
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METAL ANTI-THEFT HOUSING), REPLACING .

NOTE: Adaptation values are erased when connector is disconnected from Engine
Control Module (ECM), DTC memory content remains intact.

Special tools and equipment

Fig. 12: Identifying Special Service Tool VAS5051

Courtesy of AUDI OF AMERICA, INC.

z VAS5051 with VAG5051/1

Removing

z Connect VAS 5051 and select control module for engine electronics using "Address word" 01. See VAS
5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG 1551 SCAN
TOOL (ST), CONNECTING AND SELECTING FUNCTIONS . Ignition must remain switched on
for this.

Display on VAS 5051

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Fig. 13: VAS 5051 Scan Tool Display - Control Module Identification
Courtesy of AUDI OF AMERICA, INC.

1. - Control module identification ECM. See CHECK DTC MEMORY (SCAN TOOL FUNCTION 02)
AND ERASE DTC MEMORY (SCAN TOOL FUNCTION 05) .
2. - Contol module identification Immobilizer. See CHECK DTC MEMORY (SCAN TOOL
FUNCTION 02) AND ERASE DTC MEMORY (SCAN TOOL FUNCTION 05) .

z Start by displaying and printing out control module identification.

z Compare coding with coding versions. See CODING TABLE .
z Switch ignition off.
z Pry off both caps at wiper arms using a screwdriver.
z Loosen hex-nuts (arrows) several turns.
z Loosen wiper arms -1- from wiper axle by lightly tilting.
z Remove hex nuts completely and remove wiper arms.
z Remove rubber seal -2- from cover for plenum chamber.
z Remove cover for plenum chamber -3- and place it on windshield side.

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Fig. 14: Identifying Wiper Arms, Plenum Chamber & Rubber Seal
Courtesy of AUDI OF AMERICA, INC.

z Disengage locking lugs and remove control module connector.

z Loosen connector locking clips (arrow) and then remove connector from Engine Control Module (ECM).

Fig. 15: Removing Control Module Connector

Courtesy of AUDI OF AMERICA, INC.

Installing

Installation is reverse of removal, noting the following:

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z Bend back locking lug of bracket.

The following operations must be carried out after installing Engine Control Module:

z Activate Engine Control Module (ECM) in "Guided Fault Finding" below subject heading "Engine
Control Module (ECM), replacing".

Use VAS5051 tester to do so.

Engine Control Module (ECM) (with metal anti-theft housing), replacing

Removing ECMs without metal anti-theft housing. See ENGINE CONTROL MODULE (ECM)
(WITHOUT METAL ANTI-THEFT HOUSING), REPLACING .

NOTE: Adaptation values are erased when the harness connector is disconnected from
the Engine Control Module (ECM), the DTC memory content remains intact.

Remove Engine Control Module (ECM)

Removing

z Connect VAS5051 tester and select vehicle system "01 - Engine Electronics". Ignition must be switched
on for this.

Fig. 16: VAS 5051 Scan Tool Display - 01, Engine Electronics
Courtesy of AUDI OF AMERICA, INC.

VAS5051 tester display will indicate the control module identification and coding -2-.

z Always allow display of control module identification first and print it out.
z Switch ignition off.
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z Pry off both caps at wiper arms using a screwdriver.

z Loosen hex-nuts (arrows) several turns. See Fig. 17 .
z Loosen wiper arms -1- from wiper axle by lightly tilting. See Fig. 17 .
z Remove hex nuts completely and remove wiper arms.
z Remove plenum chamber cover rubber seal -2-. See Fig. 17 .
z Remove plenum chamber cover -3- and place it on windshield side. See Fig. 17 .

NOTE: Item -1- in illustration shows Engine Control Module (ECM) with anti-theft
housing.

Fig. 17: Identifying Wiper Arms, Plenum Chamber & Rubber Seal
Courtesy of AUDI OF AMERICA, INC.

z Use a screwdriver to press locking lug of bracket (arrow) to side and then remove Engine Control Module
(ECM) toward front.

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Fig. 18: Pressing Locking Lug Of Bracket

Courtesy of AUDI OF AMERICA, INC.

To restrict accessibility (for theft prevention) to the harness connectors and Engine Control Module (ECM), the
Engine Control Module (ECM) -1- is screwed to a metal anti-theft housing -4- via a locking mechanism -2- and
snap-off screws -3-.

Fig. 19: Identifying Engine Control Module (ECM) With Metal Anti-Theft Housing
Courtesy of AUDI OF AMERICA, INC.

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The threads on snap-off screws are coated with locking compound to make it more difficult to remove the snap
-off screws.

To disconnect harness connectors from Engine Control Module (ECM) (e.g. when connecting a test box or
when replacing ECM), the ECM must be removed from metal anti-theft housing. This procedure is described as
follows.

The following equipment is required:

z Heat gun -1- (from VAS1978 Wiring Harness Repair Kit)

z Adapter nozzle -2- (also from VAS1978 Wiring Harness Repair Kit)

Fig. 20: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

z Standard locking pliers

Procedure:

WARNING: The following work steps must be adhered to exactly to avoid damage
(burning) of wires, harness connectors, insulation and control modules!
Observe operating instructions of heat gun.

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Fig. 21: Identifying Engine Control Module (ECM) With Metal Anti-Theft Housing
Courtesy of AUDI OF AMERICA, INC.

z "Flip" Engine Control Module (ECM) with anti-theft housing in direction of engine compartment so that
the locking mechanism (item -2- in illustration) becomes visible and place a clean rag below Engine
Control Module (ECM) with anti-theft housing.

Fig. 22: Identifying Heat Gun Adjustments

Courtesy of AUDI OF AMERICA, INC.

z Adjust the heat gun as shown in illustration, i.e. temperature adjustment -2- to maximum heat output and
two-stage switch for air mass -3- to position 3.

NOTE: Next, use heat gun to heat threads of locking mechanism in which the snap-off
screws are screwed into. This step loosens locking compound on threads of
snap-off screws for easier removal.
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WARNING: By heating the locking mechanism threads, the snapf-off screws and
parts of the metal anti-theft housing will also become very hot. Be careful
not to get burned! If possible, also make sure that only the threads are
heated and that no parts are in the vicinity. If necessary, cover them.

Fig. 23: Identifying Heat Gun Nozzle

Courtesy of AUDI OF AMERICA, INC.

z Guide nozzle -1- of heat gun to locking mechanism threads so that the nozzle "encloses" threads. It is OK
to let nozzle make contact at upper end of metal anti-theft housing.
z Switch on heat gun and heat up thread for approx. 20 to 25 seconds.

Fig. 24: Removing Snap-Off Screw

Courtesy of AUDI OF AMERICA, INC.

z Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of
arrow.
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The procedure for second snap-off screw is exactly same. Be very careful since control module connector is in
close proximity.

Fig. 25: Identifying Heat Gun Nozzle

Courtesy of AUDI OF AMERICA, INC.

z Guide nozzle -1- of heat gun to locking mechanism threads again so that nozzle "encloses" threads. It is
OK to let nozzle make contact at upper end of metal anti-theft housing.
z Switch on heat gun and heat up threads for approx. 20 to 25 seconds.

Fig. 26: Removing Snap-Off Screw

Courtesy of AUDI OF AMERICA, INC.

z Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of
arrow.

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The Engine Control Module (ECM) can now be removed from metal anti-theft housing.

z Disengage connectors from Engine Control Module (ECM) and then disconnect connectors.
z Remove old Engine Control Module (ECM) and insert new one.

Installing Engine Control Module (ECM)

Installation is the reverse order of removal, noting the following:

After repairs are complete, the metal anti-theft housing must be reinstalled. Use new snap-off screws.

z Bend back locking tab on bracket.

After installing a new Engine Control Module (ECM), the following work steps must be performed:

z Activate Engine Control Module (ECM) in "Guided Troubleshooting" below subject heading "Engine
Control Module (ECM), replacing".

Use VAS5051 tester to do so.

Malfunction Indicator Lamp (MIL) -K83- in instrument cluster

If the Engine Control Module (ECM) recognizes a malfunction that may adversely affect emission levels, the
MIL comes on to indicate this.

When ignition is turned on, the ECM turns on MIL. Shortly after starting engine, ECM will turn off MIL, unless
a malfunction exists that affects quality of exhaust emissions, or signal from ECM to MIL is malfunctioning.

While engine is running, if a malfunction occurs that affects exhaust emissions, ECM will turn on MIL. (these
malfunctions are located in DTC table). At same time, ECM store this fault in memory.

The MIL can be switched on with a flashing and/or steady light. In either case fault memory is to be queried.
See CHECK DTC MEMORY (SCAN TOOL FUNCTION 02) AND ERASE DTC MEMORY (SCAN
TOOL FUNCTION 05) .

Steady light

A malfunction is present that affects exhaust emissions. Check Motronic-ECM and/or automatic transmission
fault memory (if available).

If a driveability issue exists and/or a customer concern is present and MIL does not turn on, fault memory must
be queried. Some malfunctions may not turn on the MIL immediately, but are still store in fault memory. These
malfunctions may not be recognized by ECM until next ignition cycle.

Flashing light

A malfunction is present that may cause damage to catalytic converter (e.g. engine misfire) during current
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driving conditions. In this case the vehicle can only be driven with reduced engine power!

Malfunction Indicator Lamp (MIL) -K83- checking

Checking function of control lamp

z Turn ignition on.

z The fault indicator for self diagnosis (MIL) must be turned on.

z Start engine.
z Shortly after starting engine, the MIL will turn off if there are no malfunctions stored in fault
memory that affect exhaust emissions.

NOTE: The signal to turn on MIL is sent from ECM to instrument cluster via CAN-Bus
communications. Data transfer between ECM and other CAN-able control
modules, checking. See DATA EXCHANGE, MOTRONIC (CAN-BUS),
CHECKING .

Idle speed, checking

Special tools and equipment

z VAS5051 with VAG5051/1

Fig. 27: Identifying Special Service Tool VAS5051

Courtesy of AUDI OF AMERICA, INC.

Test requirements

z Exhaust system free of leaks.

z Coolant temperature at least 80° C.
z Electrical consumers switched off (radiator fan must NOT run during test).
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z A/C switched off.

z No pressure gauges (for example, for fuel pressure test) connected.

NOTE: z Idle speed cannot be adjusted.

z Idle speed is checked during basic setting of engine.
z During basic setting, the Evaporative Emission (EVAP) canister purge
regulator valve -N80- is closed and A/C compressor is switched off

Test sequence

z Connect VAS 5051. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS
and select 01 - engine electrical. The engine must be running at idle.
z Check DTC Memory. See CHECK DTC MEMORY (SCAN TOOL FUNCTION 02) AND ERASE
DTC MEMORY (SCAN TOOL FUNCTION 05) . There must not be any DTCs stored. Repair
malfunctions if necessary, erase DTC memory, switch engine off and start again, road test vehicle and
check DTC memory again as a control measure.
z Let engine continue to run at idle.

CAUTION: Electric radiator fan must not run.

Display on VAS 5051:

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Fig. 28: VAS 5051 Scan Tool Display - Idle Speed Checking (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "04 - Basic setting".

Display on VAS 5051:

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Fig. 29: VAS 5051 Scan Tool Display - Idle Speed Checking (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max. entered value = 255

z Enter "056" for "display group number 056" in zone -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:

Fig. 30: VAS 5051 Scan Tool Display - Idle Speed Checking (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Check whether engine speed (RPM) in display field -1- (actual speed) is within permitted tolerance range.

DISPLAY GROUP 056: IDLE STABILIZATION WITH ENGINE AT IDLE AND OPERATING
TEMPERATURE

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Display fields
1 2 3 4
Display group 056: Idle stabilization with engine at idle and operating temperature
Display xxx /min xxx /min x.x % XXXXX
Indicated Engine speed (actual) Engine Idle Operating conditions
speed control
(specified) Torque
change
Specified 700 to 820 RPM 760 RPM x.x % 00000
value
Notes If specified value is not Significance of numbers. See
obtained. See SIGNIFICANCE SIGNIFICANCE OF 5 DIGIT
OF 5 DIGIT INDICATION OF INDICATION OF DISPLAY
DISPLAY GROUP 056 GROUP 056

NOTE: z Engine speed in display field 1 (actual engine speed) is current engine
speed.
z Engine speed in display field 2 (specified engine speed) is a theoretical
engine speed calculated by ECM.
z At idle, the ECM always attempts to adapt engine speed (actual) to
specified engine speed (specified).
z This means that engine speed (actual) must always approximately match
engine speed (specified) at idle.
z Display fields 3 and 4 provide information, but are not relevant for
checking idle speed.

Display on VAS 5051:

Fig. 31: VAS 5051 Scan Tool Display - Idle Speed Checking (4 Of 4)
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Courtesy of AUDI OF AMERICA, INC.

If the specified value is obtained:

z Exit function "04 - Basic setting" by pressing <- button.

If specified value is not obtained:

z Check DTC memory again. See CHECK DTC MEMORY (SCAN TOOL FUNCTION 02) AND
ERASE DTC MEMORY (SCAN TOOL FUNCTION 05) .
z If DTC memory has been erased, generate readiness code. See READINESS CODE, GENERATING .

If idle speed is too high or low and there are no DTCs in DTC memory, the following tests (marked with
dots) must be performed:

z False air in intake air system, checking. See INTAKE SYSTEM, CHECKING FOR LEAKS
(UNMETERED AIR) .
z Check throttle valve control module. See THROTTLE VALVE CONTROL MODULE -J338-,
CHECKING .
z Evaporative Emission (EVAP) canister purge regulator valve always open, checking. See FUEL TANK
VENTILATION SYSTEM, CHECKING .
z Perform adaptation of throttle valve control module. See THROTTLE VALVE CONTROL MODULE
-J338-, ADAPTING .

Significance of 5 digit indication of display group 056

SIGNIFICANCE OF 5 DIGIT INDICATION OF DISPLAY GROUP 056

xxxxx Display field 4
0 A/C compressor
0 = A/C compressor off
1 = A/C compressor on
0 Indication always 0
0 A/C readiness maximum heating/cooling power
0 Indication always 0
0 Power steering pressure
0 = no signal from pressure switch for power steering
1 = signal from pressure switch for power steering (steering at end position, fast steering
movement)

System pressure, fuel pressure regulator and residual pressure, checking

Special tools and equipment

z VAG1318

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Fig. 32: Identifying Special Service Tool (VAG1318)

Courtesy of AUDI OF AMERICA, INC.

z VAG1318/7

Fig. 33: Identifying Special Service Tool (VAG1318/7)

Courtesy of AUDI OF AMERICA, INC.

z VAG1318/17 (2x)

NOTE: Fuel pressure regulator regulates fuel pressure according to intake manifold
pressure. This ensures that pressure drop at fuel injectors remains same for
each speed and load range of engine.

Test requirements:

z Fuel Pump (FP) OK, checking. See FUEL PUMP (FP) RELAY -J17-, CHECKING AND
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ACTIVATING .
z Fuel Pump (FP) OK, checking:

See FUEL PUMP AND SENDER FOR FUEL GAUGE -G-, COMPONENT OVERVIEW .

z Fuel filter OK
z Battery voltage at least 12.7 V

WARNING: Fuel system is under pressure! Place a cloth around connection point
before opening system. Then release pressure by carefully loosening
connection point.

Checking system pressure

z Remove engine cover (arrows).

Fig. 34: Removing Engine Cover

Courtesy of AUDI OF AMERICA, INC.

z Remove fastener -1- and remove cover from over coolant reservoir (arrow).

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Fig. 35: Removing Engine Cover Over Coolant Reservoir

Courtesy of AUDI OF AMERICA, INC.

z Open fuel filler flap briefly (pressure release).

z Remove fuel supply hose -1- (with white marking) from supply line, press release button for this.

Fig. 36: Removing Fuel Supply Hose -1- (With White Marking) From Supply Line
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1318 using adapters 1318/7 and 1318/17 (2 pieces) at supply line.

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Fig. 37: Connect VAG1318 Using Adapters 1318/7 And 1318/17 At Supply Line
Courtesy of AUDI OF AMERICA, INC.

z Open shut-off valve of pressure gauge. The lever points in the direction of flow.
z Start engine and let run at idle.
z Measure fuel pressure.
z Specification: about 2.5 bar positive pressure

z Disconnect vacuum hose at fuel pressure regulator (arrow).

Fig. 38: Disconnecting Vacuum Hose At Fuel Pressure Regulator

Courtesy of AUDI OF AMERICA, INC.

z Fuel pressure must rise to about 3.0 bar positive pressure.

z Switch ignition off.
z Check for proper seal and residual pressure by observing pressure drop on pressure gauge.
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z After 10 minutes, there must be at least 1.5 bar positive pressure

If residual pressure drops below 1.5 bar positive pressure:

z Start engine and let run at idle.

z Wait until pressure has built up, and then switch off ignition. Immediately close shut-off valve of
VAG1318 pressure gauge (lever perpendicular to direction of flow - arrow-).

Fig. 39: Identifying Shut-Off Valve Of VAG1318 Pressure Gauge

Courtesy of AUDI OF AMERICA, INC.

z Observe pressure drop on pressure gauge.

If pressure does not drop now:

z Test check-valve on transfer Fuel Pump (FP).

If pressure drops again:

z Open shut-off valve of VAG1318 pressure gauge (lever in direction of flow -arrow-).
z Start engine and let run at idle.
z Wait until pressure has built up, and then switch off ignition. Then immediately clamp return line (with
blue marking) completely closed.

If pressure does not drop now:

z Replace fuel pressure regulator

If pressure drops again:

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z Check wire connections, O-rings at fuel rail and fuel injectors for proper seal.
z Check whether pressure gauge is properly sealed.

NOTE: Before disconnecting pressure gauge, release pressure by opening shut -off
valve. Hold a container in front of connection for this.

Fuel injectors, checking

Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31

Fig. 40: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Checking internal resistance

z Remove engine cover (arrows).

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Fig. 41: Removing Engine Cover

Courtesy of AUDI OF AMERICA, INC.

z Disconnect harness connector at fuel injector to be tested.

z Connect a multimeter to individual fuel injectors.
z Specification: 12 to 13 ohm(at room temperature)

Fig. 42: Checking Fuel Injector Resistance

Courtesy of AUDI OF AMERICA, INC.

If specified value is not obtained:

z Replace fuel injector. See FUEL INJECTORS, REMOVING AND INSTALLING .

If specified value is obtained:

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z Check the voltage supply.

Checking voltage supply

Test requirements

z Fuel Pump (FP) OK, checking. See FUEL PUMP (FP) RELAY -J17-, CHECKING AND
ACTIVATING .
z Fuse for fuel injectors OK

See SYSTEM WIRING DIAGRAMS .

z Disconnect harness connector at fuel injector to be tested.

Fig. 43: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1527B voltage tester as follows:

FUEL INJECTOR CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector Measure to
Terminal
1 Engine Ground (GND)

z Turn the ignition on.

z LED must light up.

If LED does not light up:

z Check wire connection between terminal 1 and fuse for fuel injector for open circuit.

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See SYSTEM WIRING DIAGRAMS .

z Repair open circuit if necessary.

If LED lights up, go to CHECKING ACTIVATION OF FUEL INJECTORS .

Checking activation of fuel injectors

Test requirement:

z Internal resistance of valve OK

z Slide back rubber boot of fuel injector connector, but leave connector connected.
z Connect VAG1527B voltage tester between sockets 2 (signal) and 1 (B+).

Fig. 44: Checking Activation Of Fuel Injectors With VAG1527B

Courtesy of AUDI OF AMERICA, INC.

z Operate starter briefly (engine can also start).

z LED must blink.

NOTE: Voltage testers do not go out completely during low current pick-up between
activations by ECM, but rather continue to glow a little and then get slightly
brighter during activation.

If LED does not blink:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .

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Fig. 45: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:

FUEL INJECTOR CIRCUIT TEST - OPENS/SHORTS

Fuel injector harness connector VAG1598/31 test box
Cylinder Terminal Socket
1 2 96
2 2 89
3 2 97
4 2 88

z Repair open circuit or short circuit if necessary.

If wire connection is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Fuel rail with fuel injectors, disassembling and assembling

NOTE: The following list refers to items in Fig. 46 .

1. - Fuel injector insert - 3 Nm

z Insert with locking compound

2. - O-ring
z Removing and installing. See FUEL INJECTORS, REMOVING AND INSTALLING

z Always replace

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z Coat with clean engine oil

3. - Fuel injectors
z Removing and installing. See FUEL INJECTORS, REMOVING AND INSTALLING

4. - Supply hose
5. - Return hose
6. - Harness connector
z For injectors

z 4x

7. - Socket-head screw - 10 Nm
8. - Fuel pressure regulator
9. - O-ring
z Always replace

10. - O-ring
z Always replace

11. - Retaining clip

12. - Fuel rail
13. - O-ring
z Removing and installing. See FUEL INJECTORS, REMOVING AND INSTALLING .

z Always replace

z Coat with clean engine oil

14. - Retaining clip

z Make sure clip is correctly seated on fuel injector and fuel rail

15. - 10 Nm
16. - Throttle valve control module -J338 -
z With throttle drive (power accelerator actuation) - G186 -, angle sensor -1- for throttle drive (power
accelerator actuation) - G187 -, and angle sensor -2- for throttle drive (power accelerator actuation)
- G188 -
17. - Gasket
z Always replace

18. - 10 Nm
19. - Intake Air Temperature (IAT) sensor -G42-
20. - O-ring
z Always replace

21. - Intake manifold

z Removing

See INTAKE MANIFOLD, REMOVING AND INSTALLING .

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Fig. 46: Exploded View Of Intake Manifold And Fuel Rail Assembly
Courtesy of AUDI OF AMERICA, INC.

Fuel injectors, removing and installing

Removing

z Remove engine cover (arrows).

Fig. 47: Removing Engine Cover

Courtesy of AUDI OF AMERICA, INC.

z Disconnect wiring/connectors at:

{ Intake Air Temperature (IAT) sensor -G42-

{ Camshaft Position (CMP) sensor 2 -G163 -

{ Throttle valve control module -J338-

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WARNING: Fuel system is under pressure! Place a cloth around connection point
before opening system. Then release pressure by carefully loosening
connection point.

z Disconnect fuel supply line -1- and fuel return line -2- by pressing on release buttons at separating point.

Fig. 48: Disconnecting Fuel Supply Line And Fuel Return Line
Courtesy of AUDI OF AMERICA, INC.

z Disconnect vacuum hose from fuel pressure regulator (arrow).

Fig. 49: Disconnecting Vacuum Hose From Fuel Pressure Regulator

Courtesy of AUDI OF AMERICA, INC.

z Disconnect electrical connection -1-. See Fig. 50 .

z Remove cable channel -2-. See Fig. 50 .

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z Unscrew 2 socket-head bolts (arrows) for fuel rail.

Fig. 50: Removing Fuel Rail

Courtesy of AUDI OF AMERICA, INC.

z Remove fuel rail with injectors from intake manifold simultaneously upward and set aside in rear of
engine compartment on a clean cloth.
z Disengage retaining clip and remove fuel injector.

NOTE: Fuel lines must be disconnected before replacing fuel rail.

Installing

Installation is reverse of removal, noting the following:

z Remove O-rings at all opened connections. (Never remove plastic cap from head of fuel injector, to
replace front O-ring - pry O-ring off over plastic cap).
z Always coat o-rings with clean engine oil.
z Make sure fuel injectors are in place and seated correctly
z Check clip for unobstructed fitting.
z Place fuel rail with secured fuel injectors onto intake manifold, and apply uniform pressure to press it in.

Tightening torque

TIGHTENING TORQUE: FUEL RAIL

Component Nm
Fuel rail at intake manifold 10

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Injection quantity, proper seal and spray pattern of fuel injectors, checking

Special tools and equipment

z VAG1348/3A
z VAG1594A
z VAG1598/31
z VAG 1602

Fig. 51: Identifying Special Service Tools

Courtesy of AUDI OF AMERICA, INC.

Test requirement:

z Fuel pressure OK, checking. See SYSTEM PRESSURE, FUEL PRESSURE REGULATOR AND
RESIDUAL PRESSURE, CHECKING .

Test sequence

z Remove fuel rail including fuel injectors from intake manifold. See FUEL INJECTORS, REMOVING
AND INSTALLING . Fuel lines remain connected.
z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .

Checking proper seal

z Bridge terminals 1 and 65 at test box using adapter cables from VAG1594A connector test kit (this step
supplies Ground (GND) to one side of relay coil for Fuel Pump (FP) relay).
z Switch ignition on.
z Fuel Pump (FP) must run.

z Check proper seal of fuel injectors (visual inspection). With Fuel Pump (FP) running, only 1-2 drops per
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minute may drip out per injector.

z If fuel loss is greater, stop Fuel Pump (FP) from running (switch off ignition) and replace faulty fuel
injector. See FUEL INJECTORS, REMOVING AND INSTALLING .

Checking injection quantity

z Insert fuel injector to be tested in a measuring glass from VAG1602 injection quantity test device.
z Connect one terminal of fuel injector to engine Ground (GND) using an adapter cable and an alligator
clip from VAG1594A connector test kit.

Fig. 52: Connecting Terminal Of Fuel Injector To Engine Ground Using VAG1348/3A Remote
Control
Courtesy of AUDI OF AMERICA, INC.

z Connect second terminal of fuel injector to B+ using VAG1348/3A remote control, VAG1348/3 -2
adapter cable and assisting cable.
z Bridge terminals 1 and 65 at test box using adapter cables from VAG1594A connector test kit (this step
supplies Ground (GND) to one side of relay coil for Fuel Pump (FP) relay).
z Switch ignition on.
z Fuel Pump (FP) must run.

z Activate VAG1348/3A remote control for 30 seconds.

z Perform measurement on all fuel injectors.
z After all four fuel injectors have been activated, place measuring glasses on an even surface.
z Specified value for each fuel injector: 179 +/- 14 ml

z If measured value of one or more fuel injectors is outside of specified range, switch Fuel Pump (FP) off
(switch ignition off) and replace faulty fuel injector. See FUEL INJECTORS, REMOVING AND
INSTALLING .
z If measured value of all fuel injectors is outside of the specified range, check fuel pressure. See SYSTEM
PRESSURE, FUEL PRESSURE REGULATOR AND RESIDUAL PRESSURE, CHECKING .

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NOTE: Also check spray pattern when checking injection quantity. Spray pattern
must be the same for all injectors

z Re-install fuel injectors together with fuel rail. See INSTALLING .

Fuel Pump (FP) relay -J17-, checking and activating

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS 5051 with VAS 5051/1

Fig. 53: Identifying Special Service Tools

Courtesy of AUDI OF AMERICA, INC.

See COMPONENT LOCATIONS, OVERVIEW .

Voltage is supplied to the Fuel Pump (FP) and several components of the injection system via the Fuel Pump
(FP) relay -J17-.

Engine must be turning for Fuel Pump (FP) relay -J17- to close, i.e. the relay does not receive Ground (GND)
(via the Engine Control Module - ECM -) until the ECM recognizes RPM signals.

Test requirement:

z Battery voltage at least 12.7 V

Function test of Fuel Pump (FP) relay

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z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Connect VAS5051 tester scan tool and select the control module for engine electronics using "address
word" 01. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM
OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS .
z Initiate output Diagnostic Test Mode. See OUTPUT DIAGNOSTIC TEST MODE (DTM) (SCAN
TOOL FUNCTION 03) and activate Evaporative Emission (EVAP) canister purge regulator valve -N80-
(Tank Ventilation Valve).
z Fuel Pump (FP) relay (at position 4 of micro-central electronics in driver's footwell, left) must
trigger and Fuel Pump (FP) must run.

Fig. 54: Locating Fuel Pump Relay

Courtesy of AUDI OF AMERICA, INC.

z Exit function "03 - Output check diagnosis" by pressing <- button.

A. - If relay does not trigger:

{ Check voltage supply for Fuel Pump (FP). See CHECKING VOLTAGE SUPPLY FOR FUEL
PUMP (FP) .
{ Check activation of Fuel Pump (FP) relay. See CHECKING VOLTAGE SUPPLY FOR FUEL
PUMP (FP) .
B. - If relay triggers, but Fuel Pump (FP) does not run:
{ See CHECK VOLTAGE SUPPLY FOR FUEL PUMP (FP) AND COMPONENTS (via Fuel
Pump -FP- relay).

Checking voltage supply for Fuel Pump (FP)

z Remove fuel pump relay.

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Fig. 55: Locating Fuel Pump Relay Terminal 17 In Relay Socket

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter to terminal 17 of relay socket and Ground (GND) for voltage measurement.
z Specification: approx. battery voltage

If specified value is not obtained:

z Replace the micro -central electronics.

Checking activation of Fuel Pump (FP) relay

z Turn off ignition.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Connect socket 65 and socket 1 of test box to each other using adapter cable from VAG1594A connector
test kit.

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Fig. 56: Identifying Test Box Sockets

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Fuel Pump (FP) relay (at position 4 of micro -central electrics in driver's footwell, left) must
trigger.

If relay triggers now, but didn't during output DTM:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

If relay does not trigger:

z Switch ignition off.

z Remove adapter cable.
z Remove Fuel Pump (FP) relay.
z Connect multimeter to terminal 19 of relay socket and Ground (GND) for voltage measurement.

FUEL PUMP RELAY CIRCUIT TEST - ACTIVATION

Micro-central electronics in driver-side footwell, left, position 4 Terminal Measure against
19 Engine ground

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Fig. 57: Identifying Fuel Pump Relay Terminals In Relay Socket

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Specification: approx. battery voltage

If specified value is not obtained:

z Check wire connections.

See SYSTEM WIRING DIAGRAMS .

If specified value is obtained:

z Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:

FUEL PUMP RELAY CIRCUIT TEST - OPENS/SHORTS

Micro-central electronics in driver-side footwell, left, position 4 VAG1598/31 test box
Terminal Socket
16 65

z Repair open circuit or short circuit if necessary.

If no malfunctions are detected:

z Replace Fuel Pump (FP) relay -J17-.

z Re-connect Engine Control Module (ECM).

Check voltage supply for Fuel Pump (FP) and components

z Disconnect fuses S228, S232, S234 and S243 (positions 28, 32, 34 and 43) from fuse holder.
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Fig. 58: Identifying Fuse Panel

Courtesy of AUDI OF AMERICA, INC.

z Initiate output Diagnostic Test Mode (DTM). See OUTPUT DIAGNOSTIC TEST MODE (DTM)
(SCAN TOOL FUNCTION 03) and activate Evaporative Emission (EVAP) canister purge regulator
valve -N80-.
z Connect multimeter for voltage measurement to Ground (GND) and to one terminal of the following
fuses in the fuse holder.

FUEL PUMP FUSE VOLTAGE CHECK

Fuse Specified value at one of the terminals
S228 approx. battery voltage
S232 approx. battery voltage
S234 approx. battery voltage
S243 approx. battery voltage

If specified values are not obtained:

z Repeat test at another terminal of fuse socket.

If specified values are not obtained again:

z Check wire connections.

See SYSTEM WIRING DIAGRAMS .

If no malfunctions are detected:

z Replace Fuel Pump (FP) relay -J17-.

z Re-insert fuses.

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Mass Air Flow (MAF) sensor - G70-, checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

Fig. 59: Identifying Special Service Tools

Courtesy of AUDI OF AMERICA, INC.

See COMPONENT LOCATIONS, OVERVIEW .

Test requirements:

z Coolant temperature at least 80° C.

z Electrical consumers switched off (radiator fan must NOT run during test).
z A/C switched off.

Checking function

z Connect VAS5051 tester scan tool and select the control module for engine electronics using "address
word" 01. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM
OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS . Engine must
run at idle for this.

Display on VAS 5051:

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Fig. 60: VAS 5051 Scan Tool Display - MAF Sensor Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Select "04 - Basic setting."

Display on VAS 5051:

Fig. 61: IVAS 5051 Scan Tool Display - MAF Sensor Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max. entered value = 255

z In display field -2- enter "002" to select "display group number 002" and press -Q- button to confirm
input.

Indicated on display:

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Fig. 62: VAS 5051 Scan Tool Display - MAF Sensor Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check specified values for load detection in display fields -3- and -4-.

DISPLAY GROUP 002: AIR MASS TAKEN IN WITH ENGINE AT IDLE AND OPERATING
TEMPERATURE
Display fields
1 2 3 4
Display group 002: Air mass taken in with engine at idle and operating temperature
Display xxx /min xx.x % x.x ms xxx.x g/s
Indicated Engine speed Load mean injection time Air mass
(RPM)
(in increments
of 40)
Specified 700 to 820 RPM 10 to 1.0 to 4.0 ms 2.0 to 4.5 g/s
value 25%
Notes --- --- If specified value is not obtained: Evaluation display field 3.
See EVALUATION DISPLAY GROUP 002

If specified value is obtained:

z Exit function "04 - Basic setting" by pressing <- button.

Evaluation display group 002

EVALUATION DISPLAY GROUP 002

Display
field: 3 Possible cause Corrective action

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less than z Smaller values are only possible

1.0 ms when driving in deceleration mode
larger than z Engine under load due to power z Reduce load (A/C system/power
4.0 ms accessories. steering/generator)
z Poor idle (engine not running on Check spark plugs.
z
all cylinders) z See FUEL INJECTORS, CHECKING .
z Throttle valve control module - z See THROTTLE VALVE CONTROL
J338- faulty MODULE -J338-, CHECKING
Display Possible cause Corrective action
field: 4
smaller z Large false air mass between Check intake system for leaks (false air).
z
than 2.0 intake manifold and Mass Air See INTAKE SYSTEM, CHECKING
g/s Flow (MAF) sensor FOR LEAKS (UNMETERED AIR) .
z Voltage supply of Mass Air Flow z Check voltage supply. See VOLTAGE
(MAF) sensor or wire connections SUPPLY FOR MASS AIR FLOW (MAF)
to Engine Control Module (ECM) SENSOR, CHECKING
larger than z Engine under load due to power z Reduce load (A/C system/power
4.5 g/s accessories steering/generator)
z Voltage supply of Mass Air Flow z Check voltage supply. See VOLTAGE
(MAF) sensor or wire connections SUPPLY FOR MASS AIR FLOW (MAF)
to Engine Control Module (ECM) SENSOR, CHECKING

Voltage supply for Mass Air Flow (MAF) sensor, checking

Test requirements:

z Fuse for Mass Air Flow (MAF) sensor OK.

See SYSTEM WIRING DIAGRAMS .

z Fuel pump relay OK; checking. See FUEL PUMP (FP) RELAY -J17-, CHECKING AND
ACTIVATING .

NOTE: Voltage supply to Mass Air Flow (MAF) sensor is from Fuel Pump (FP) Relay -
J17-.

z Disconnect connector (arrow) to Mass Air Flow (MAF) sensor

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Fig. 63: Identifying Mass Air Flow (MAF) Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect the multimeter to the following:

MAF SENSOR CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector Terminal Measure to
2 Engine Ground (GND)

z Operate starter briefly (engine can be started).

z Specification: approx. battery voltage

If specified value is not obtained:

z Check wire connection from terminal 2 of connector to Fuel Pump (FP) relay via fuse for open circuit and
short circuit to Ground (GND):

See SYSTEM WIRING DIAGRAMS .

z Repair open circuit or short circuit if necessary.

z Connect multimeter to terminal 2 and terminal 3 of connector for voltage measurement.

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Fig. 64: Identifying Mass Air Flow (MAF) Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Operate starter briefly.

z Specification: approx. battery voltage

NOTE: Ground (GND) from ECM is present at terminal 3 of connector.

If specified value is not obtained:

z Check wire connections. See CHECK WIRE CONNECTIONS FOR MASS AIR FLOW (MAF)
SENSOR .
z Connect multimeter to terminal 3 and terminal 4 of connector for voltage measurement.

Fig. 65: Identifying Mass Air Flow (MAF) Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.
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z Switch ignition on.

z Specification: about 5 V

If specified value is not obtained:

z Check wire connections. See CHECK WIRE CONNECTIONS FOR MASS AIR FLOW (MAF)
SENSOR .

Check wire connections for Mass Air Flow (MAF) sensor

NOTE: Signal wire is also checked during wire test.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .

Fig. 66: Identifying Mass Air Flow (MAF) Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:

MASS AIR FLOW SENSOR OPEN CIRCUIT AND SHORT CIRCUIT TO GROUND CHECK
Harness connector Terminal VAG1598/31 test box Socket
3 27
4 53
5 29

z Repair open circuit or short circuit if necessary.

z Also check all wires for short circuit to each other.

If wire connection is OK:

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z Replace Mass Air Flow (MAF) sensor -G70-.

Intake system, checking for leaks (unmetered air)

Special tools and equipment

z VAS5051 with VAG5051/1

Fig. 67: Identifying Special Service Tool VAS5051

Courtesy of AUDI OF AMERICA, INC.

z Engine leak detection spray G 001 800 A1

NOTE: z Negative pressure in the intake system sucks in the leak detection spray
with unmetered air. Leak detection spray decreases ignition quality and
performance of fuel mixture. This causes a reduction in engine speed and
a sharp increase of CO content.
z It is absolutely necessary to follow safety precautions listed on can.

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select the control module for engine electronics
using "address word" 01. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND
INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING
FUNCTIONS . Engine must run at idle for this.

Display on VAS 5051:

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Fig. 68: VAS 5051 Scan Tool Display - Intake System, Checking For Leaks (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Select "Read Measuring Value Block."

Display on VAS 5051:

Fig. 69: VAS 5051 Scan Tool Display - Intake System, Checking For Leaks (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max. entered value = 255

z In display field -2- enter "001" for "display group number 001" and press -Q- button to confirm input.

Display on VAS 5051:

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Fig. 70: VAS 5051 Scan Tool Display - Intake System, Checking For Leaks (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Make note of engine speed in display field 1.

z Spray intake system parts with engine leak detection spray in a systematic manner.

If engine speed decreases:

z Check sprayed area of intake system for leaks and repair.

z Exit function "08 - Read Measuring Value Block" by pressing <- button.

Display on VAS 5051:

Fig. 71: VAS 5051 Scan Tool Display - Intake System, Checking For Leaks (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

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z Under -1- select diagnostic function "06 - End output".

z Switch ignition off.

Secondary air system, checking

The Secondary Air Injection (AIR) system causes catalytic converter to heat up more quickly, resulting in
earlier operational readiness following cold start.

Principle

Due to over-enrichment of mixture during cold start phase, there is an increased amount of un-burned carbon
monoxide in the exhaust. Secondary Air Injection (AIR) improves secondary oxidation in catalytic converter
and therefore reduces emissions. The heat produced by secondary oxidation greatly reduces start-up time for
catalytic converter, therefore improving exhaust quality during cold start phase significantly.

Function

z In the cold start phase, the ECM - 2- activates secondary air pump - 12- via relay for secondary air pump -
1-. Air reaches the combination valve for Secondary Air Injection (AIR) -10-.
z The Secondary Air Injection (AIR) valve -3- is activated in parallel, which allows vacuum to reach
combination valve for Secondary Air Injection (AIR) -10- and vacuum diaphragm for boost pressure
regulation -7-. The combination valve for Secondary Air Injection (AIR) thereby opens path for
secondary air to exhaust channels of cylinder head.
z To prevent unnecessary torque losses, secondary air is routed to turbine wheel of turbocharger -8- so that
air can get directly into catalytic converter. For this, boost pressure regulation pressure unit opens boost
pressure valve -7-. The pressure unit, designed as a double reservoir, has a vacuum connection for this on
the intake side.

NOTE: The following list refers to items in Fig. 72 .

1. - Secondary Air Injection (AIR) Pump Relay -J299-

2. - Motronic Engine Control Module (ECM) -J220 -
3. - Secondary Air Injection (AIR) Solenoid Valve -N112-
4. - Intake tube
5. - Check valve
z Installation position (light/dark side): Arrow points in direction of flow, as shown

6. - Vacuum reservoir
7. - Pressure unit for boost pressure regulation
8. - Turbocharger
9. - Cylinder head
10. - Combination valve for secondary air injection (AIR)
11. - Air filter housing
12. - Secondary Air Injection (AIR) Pump Motor -V101-
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Fig. 72: Identifying Secondary Air System Components

Courtesy of AUDI OF AMERICA, INC.

Secondary Air Injection (AIR) Solenoid Valve -N112- checking

Special tools and equipment

z V.A.G. 1526 A
z V.A.G. 1527 B
z V.A.G. 1594 A
z V.A.G. 1598/31
z VAS 5051

or

z V.A.G. 1551 with V.A.G. 1551/3 A

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Fig. 73: Identifying Special Service Tools

Courtesy of AUDI OF AMERICA, INC.

See COMPONENT LOCATIONS, OVERVIEW .

Test requirements:

z Output Check Diagnosis completed.

Checking internal resistance

z Disconnect harness connector at Secondary Air Injection (AIR) Solenoid Valve -N112-.
z Connect a multimeter to valve.

Fig. 74: Checking Secondary Air Injection Solenoid Valve Resistance

Courtesy of AUDI OF AMERICA, INC.

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z Specification: 12 to 13 (at room temperature)

z If specified value is not obtained, replace Secondary Air Injection (AIR) Solenoid Valve -N112-.

Voltage Supply for Secondary Air Injection (AIR) Solenoid Valve -N112- checking

z Disconnect harness connector at Secondary Air Injection (AIR) Solenoid Valve -N112-.
z Connect VAG1527B voltage tester as follows:

Fig. 75: Identifying Secondary Air Injection Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

SECONDARY AIR INJECTION SOLENOID VALVE CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector Terminal Measure to
1 Engine Ground (GND)

z Briefly operate starter (engine can be started).

z LED must light up

If LED does not light up:

z Perform the following test, indicated by dots:

z Check fuse for Secondary Air Injection (AIR) Solenoid Valve -N112-.

See SYSTEM WIRING DIAGRAMS .

z Check wire connection between terminal 1 and fuse for fuel pump relay for open circuit.

See SYSTEM WIRING DIAGRAMS .

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Fig. 76: Identifying Secondary Air Injection Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Fuel pump relay checking. See FUEL PUMP (FP) RELAY -J17-, CHECKING AND
ACTIVATING .

Checking activation of Secondary Air Injection (AIR) Solenoid Valve -N112-

z Connect VAG1527B voltage tester as follows:

Fig. 77: Identifying Secondary Air Injection Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

SECONDARY AIR INJECTION SOLENOID VALVE CIRCUIT TEST - ACTIVATION

Harness connector Terminal Measure to
2 Battery Voltage (B+)
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z Perform Output check diagnosis and activate Secondary Air Injection (AIR) Solenoid Valve - N112-. See
OUTPUT DIAGNOSTIC TEST MODE (DTM) (SCAN TOOL FUNCTION 03) .
z LED must flash

If LED does not flash or stays on constant:

z Connect Test box V.A.G. 1598/31 to engine control module (ECM) harness. Do not connect ECM. See
ELECTRICAL TESTING USING VAG1598/31 TEST BOX .
z Check the following wiring connections for open circuit or short to ground (GND) and/or battery voltage
(B+):

Fig. 78: Identifying Secondary Air Injection Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

SECONDARY AIR INJECTION SOLENOID VALVE CIRCUIT TEST - OPEN CIRCUIT OR

SHORT CIRCUIT
Harness connector Terminal VAG1598/31 test box Socket
2 9

z If necessary, repair open or short circuits.

If wiring connection is OK:

z Replace ECM. See ENGINE CONTROL MODULE (ECM) (WITHOUT METAL ANTI-THEFT
HOUSING), REPLACING .

Secondary Air Injection (AIR) Pump Relay -J299 - and checking activation

Special tools and equipment

z V.A.G. 1526 A
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z V.A.G. 1527 B
z V.A.G. 1594 A
z V.A.G. 1598/31

Fig. 79: Identifying Special Service Tools

Courtesy of AUDI OF AMERICA, INC.

Checking

See COMPONENT LOCATIONS, OVERVIEW .

z Perform Output check diagnosis and activate Secondary Air Injection (AIR) Pump Relay - J299-. See
OUTPUT DIAGNOSTIC TEST MODE (DTM) (SCAN TOOL FUNCTION 03) .
z Secondary Air Injection (AIR) Pump Relay -1- (under cover, left at bulkhead) must operate and
Secondary Air Injection Pump Motor -V101- must run in intervals. The relay -2- in this instance
does not need to be monitored (it is in regards to the Motronic Engine Control Module (ECM)
Power Supply Relay - J271-).

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Fig. 80: Locating Secondary Air Injection Pump Relay

Courtesy of AUDI OF AMERICA, INC.

A. - If relay does not operate:

{ See VOLTAGE SUPPLY FOR SECONDARY AIR INJECTION (AIR) PUMP RELAY -
J299- .
{ Check activation of secondary air injection pump relay - J299-. See CHECKING ACTIVATION
OF SECONDARY AIR INJECTION (AIR) PUMP .
B. - If relay operates, but Secondary Air Injection Pump Motor -V101- does not run:
{ See CHECKING VOLTAGE SUPPLY FOR SECONDARY AIR INJECTION (AIR) PUMP
MOTOR -V101- .

Voltage supply for Secondary Air Injection (AIR) Pump Relay -J299-

z Turn off ignition.

z Remove Secondary Air Injection (AIR) Pump Relay -1-.

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Fig. 81: Locating Secondary Air Injection Pump Relay

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter to following location (left relay carrier) to read voltage:

Fig. 82: Identifying Secondary Air Injection Pump Relay Terminals (In Relay Carrier)
Courtesy of AUDI OF AMERICA, INC.

SECONDARY AIR INJECTION PUMP RELAY CIRCUIT TEST - VOLTAGE SUPPLY

Relay carrier under the cover on left splash wall Terminal Measure to
1 Engine Ground (GND)

NOTE: The relay locations are specified on the relay carrier.

z Specification: Battery Voltage

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If specified value is not obtained:

z Perform following tests, specified by dots:

z Check Fuse S131 (50A) in Main Fuse box/Battery

Fig. 83: Locating Fuse S131 (50A)

Courtesy of AUDI OF AMERICA, INC.

z Check wire connection from Battery + (socket 30) to Fuse S131 to Secondary Air Injection (AIR)
Pump Relay -J299- (under cover, left at bulkhead) for open circuit.

See SYSTEM WIRING DIAGRAMS .

z Connect multimeter to following location (left relay carrier) to read voltage:

Fig. 84: Identifying Secondary Air Injection Pump Relay Terminals (In Relay Carrier)
Courtesy of AUDI OF AMERICA, INC.
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SECONDARY AIR INJECTION PUMP RELAY CIRCUIT TEST - VOLTAGE SUPPLY

(TERMINAL 3)
Relay carrier under the cover on left splash wall Terminal Measure to
3 Engine Ground (GND)

z Briefly operate starter (motor can start).

z Specification: Battery Voltage

If specified value is not obtained:

z Perform following test, specified by dots:

z Check Fuse S243 (in fuse holder, socket location 43).

Fig. 85: Identifying Fuse Panel

Courtesy of AUDI OF AMERICA, INC.

z Check wire connection from Secondary Air Injection (AIR) Pump Relay -J299- (under cover, left
at bulkhead) over Fuse S243 (in fuse holder, socket location 43) to Fuel Pump Relay for open
circuit.

See SYSTEM WIRING DIAGRAMS .

Checking activation of secondary air injection (AIR) pump

z Turn ignition off.

z Remove secondary air injection (AIR) pump relay.
z Connect multimeter to following location (left relay carrier) to read voltage:

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Fig. 86: Identifying Secondary Air Injection Pump Relay Terminals (In Relay Carrier)
Courtesy of AUDI OF AMERICA, INC.

SECONDARY AIR INJECTION PUMP RELAY CIRCUIT TEST - ACTIVATION

Relay carrier under the cover on left splash wall Terminal Measure to
4 Battery Positive (B+)

z Perform the Output check diagnosis and activate the Secondary Air Injection (AIR) Pump Relay -J299-.
See OUTPUT DIAGNOSTIC TEST MODE (DTM) (SCAN TOOL FUNCTION 03) .
z Specification: Battery voltage varying; because relay is turned on and off by ECM during output
check diagnosis.

If specified value is not obtained:

z Turn ignition off.

z Connect Test box V.A.G. 1598/31 to engine control module (ECM) harness. Do not connect ECM. See
ELECTRICAL TESTING USING VAG1598/31 TEST BOX .
z Check the following wiring connections for open circuit or short to ground (GND) and/or battery voltage
(B+):

SECONDARY AIR INJECTION PUMP RELAY CIRCUIT TEST - ACTIVATION

Relay carrier under the cover on left splash wall Terminal VAG1598/31 test box Socket
4 66

z If necessary, repair open or short circuits.

If no problems are found:

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z Replace Secondary Air Injection (AIR) Pump Relay -J299-.

Checking Voltage supply for Secondary Air Injection (AIR) Pump Motor -V101-

z Remove sound dampening (arrow).

Fig. 87: Removing Sound Dampening

Courtesy of AUDI OF AMERICA, INC.

z Remove connector from Secondary Air Injection (AIR) Pump Motor -V101- -1-.
z Connect the voltage tester V.A.G. 1527 B between 1 and 2.
z Perform the Output check diagnosis and activate the Secondary Air Injection (AIR) Pump Relay - J299-.
See OUTPUT DIAGNOSTIC TEST MODE (DTM) (SCAN TOOL FUNCTION 03) .
z The LED must flash

If the LED does not flash:

z Perform the following tests, indicated by dots:

z Check wiring harness from Secondary Air Injection (AIR) Pump Motor -V101- connector to
Secondary Air Injection (AIR) Pump Relay -J299- (under cover, left at bulkhead) for open circuit:

See SYSTEM WIRING DIAGRAMS .

IMPORTANT: z Check wiring harness from Secondary Air Injection (AIR) Pump Motor -
V101- to Ground (GND) location in left of engine compartment for open
circuit:

See SYSTEM WIRING DIAGRAMS .

If no problem is found:
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z Replace Secondary Air Injection (AIR) Pump Motor -V101-.

OXYGEN SENSOR (O2S) SYSTEM, CHECKING

Oxygen Sensor (O2S) and Oxygen Sensor control before catalytic converter, checking

Special tools and equipment

z V.A.G 1526 A Multimeter

z V.A.G 1594 A Connector test kit
z V.A.G 1598/31 Test box
z VAS 5051 with VAS 5051/1

Fig. 88: Identifying Special Service Tools

Courtesy of AUDI OF AMERICA, INC.

Test requirements:

z No leaks in exhaust system

z Coolant temperature at least 80° C.

Test sequence

z Connect vehicle diagnostic, testing and information system VAS 5051. See VAS 5051 VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST),
CONNECTING AND SELECTING FUNCTIONS and select vehicle system "01 -Engine electronics"
in selection. Engine must be run at idle speed.

Display on VAS 5051:

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Fig. 89: VAS 5051 Scan Tool Display - O2S And Oxygen Sensor Control Before Catalytic Converter,
Checking (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "04 - Basic setting".

Display on VAS 5051:

Fig. 90: VAS 5051 Scan Tool Display - O2S And Oxygen Sensor Control Before Catalytic Converter,
Checking (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group max. input value 255

z Enter "030" for "display group number 030" in field -2- and confirm entry by pressing -Q- button.

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Display on VAS 5051:

Fig. 91: VAS 5051 Scan Tool Display - O2S And Oxygen Sensor Control Before Catalytic Converter,
Checking (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Check specification in display field -1-.

NOTE: z By increasing engine speed specified values are achieved more quickly.
z The "Oxygen Sensor status" indicates condition of Oxygen Sensor control
and Oxygen Sensor (O2S).

DISPLAY GROUP 030: OXYGEN SENSOR (O2S) STATUS

Display fields
1 2 3 4
Display group 030: Oxygen Sensor (O2S) status
Display XXX XXX
Display Oxygen Sensor (O2S) status, bank 1, Oxygen Sensor (O2S) status, bank 1,
sensor 1 sensor 2
Range 0 = off 0 = off
1 = on 1 = on
Specified 111 110
value
Note: If specified value is not obtained. See TESTING PRIMARY VOLTAGE
If specified value is obtained but there is a DTC stored in DTC memory check oxygen
sensor adaptation values and control, see CHECKING OXYGEN SENSOR (O2S)
ADAPTATION VALUES AND OXYGEN SENSOR (O2S) CONTROL

SIGNIFICANCE OF 3-DIGIT READOUT OF DISPLAY GROUP 030

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Significance of 3-digit readout of display group 030

X X X Display fields 1 and 2:
X Oxygen Sensor (O2S) control 0 = not active; 1 = active
X Oxygen Sensor (O2S) condition: 0 = not active; 1 = active
X Condition of Oxygen Sensor (O2S) heating: 0 = not active; 1 = active

NOTE: The first digit of the 3-digit display (heating) fluctuates between 0 and 1.

Display on VAS 5051:

Fig. 92: VAS 5051 Scan Tool Display - O2S And Oxygen Sensor Control Before Catalytic Converter,
Checking (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Only continue test if display in display field -1- has reached "111" at least once.

Checking Oxygen Sensor (O2S) adaptation values and Oxygen Sensor (O2S) control

z Press the UP ARROW button twice to change "display group number 032".
z Check indication in display groups -1-and -2-.

DISPLAY GROUP 032: OXYGEN SENSOR (O2S) ADAPTATION VALUES (BANK 1, SENSOR 1)
Display fields
1 2 3 4
Display group 032: Oxygen Sensor (O2S) adaptation values (bank 1, sensor 1)
Display xx.x % xx.x %
Display Oxygen Sensor (O2S) adaptation Oxygen Sensor (O2S) adaptation value bank
value bank 1, sensor 1 at idle 1, sensor 1 at partial throttle (multiplicative)
(additive)
Specified -9.0...9.0% -25.0...25.0%
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value
Note: If the specified value is not obtained, see EVALUATION DISPLAY GROUP 032

Display on VAS 5051:

Fig. 93: VAS 5051 Scan Tool Display - Checking O2S Adaptation Values And O2S Control
Courtesy of AUDI OF AMERICA, INC.

z Press the UP-ARROW button to change "display group number 033".

z Check indication in display groups -1-and -2-.

DISPLAY GROUP 033: OXYGEN SENSOR CONTROL (BANK 1, SENSOR 1)

Display fields
1 2 3 4
Display group 033: Oxygen Sensor control (bank 1, sensor 1)
Display xx.x % x.xxx V
Display Oxygen Sensor control bank 1, Oxygen Sensor voltage bank 1, sensor 1
sensor 1
Specified In range -10.0...10.0% value must 0.130...3.600 volts
value fluctuate at least 2%
Note: If specified value is not obtained, If specified value is not obtained, see
see CONTINUED EVALUATION DISPLAY GROUP 033

Note on display field 2:

Displayed is the Oxygen Sensor (O2S) voltage signal which was prepared and smoothed in the Engine Control
Module (ECM). 1.5 V in the display corresponds to Oxygen Sensor (O2S) 1.

Continued

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If specified value in display field 1 is not obtained or if value does not fluctuate at least 2%:

z Road test vehicle in order to free oxygen sensor of possible residue and repeat test.

If specified value in display field 1 is not obtained even after road test or if value does not fluctuate at least 2%:

z Check primary voltage. See TESTING PRIMARY VOLTAGE .

z Check oxygen sensor heating. See OXYGEN SENSOR (O2S) HEATING - Z19- FOR OXYGEN
SENSOR BEFORE THREE WAY CATALYTIC CONVERTER (TWC), CHECKING .
z Check oxygen sensor before catalytic converter for aging. See OXYGEN SENSOR (O2S) AGING
(HO2S BEFORE TWC), CHECKING .

Evaluation display group 032

EVALUATION DISPLAY GROUP 032

Display field:
1/2 Possible cause Corrective action
Oxygen sensor z Leak in intake area z Check intake system for leaks and repair false
adaptation (pressure side between air. See INTAKE SYSTEM, CHECKING
value in range turbocharger and intake FOR LEAKS (UNMETERED AIR) .
manifold)
z Oil thinning z Change oil or perform swift country open) road
test
z High oil consumption
z Mass Air Flow (MAF) z Check Mass Air Flow (MAF) sensor. See
sensor faulty MASS AIR FLOW (MAF) SENSOR - G70-,
CHECKING
z Evaporative Emission z Check Evaporative Emission (EVAP) canister
(EVAP) canister purge purge regulator valve. See FUEL TANK
regulator valve remains VENTILATION SYSTEM, CHECKING
stuck in open position
z Fuel pressure too high z Check fuel pressure regulator. See SYSTEM
PRESSURE, FUEL PRESSURE
REGULATOR AND RESIDUAL
PRESSURE, CHECKING
z Fuel injector does not z See FUEL INJECTORS, CHECKING .
close
z Oxygen sensor heating zCheck oxygen sensor heating. See OXYGEN
faulty SENSOR (O2S) HEATING - Z19- FOR
z Oxygen sensor faulty
OXYGEN SENSOR BEFORE THREE WAY
CATALYTIC CONVERTER (TWC),
CHECKING

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Evaluation display group 032

EVALUATION DISPLAY GROUP 032

Display field: Possible cause Corrective action
1/2
Oxygen sensor z False air in intake area z Check intake system for leaks and repair false air.
adaptation See INTAKE SYSTEM, CHECKING FOR
value in range LEAKS (UNMETERED AIR) .
z Fuel pressure too low z Check fuel pressure regulator. See SYSTEM
PRESSURE, FUEL PRESSURE REGULATOR
AND RESIDUAL PRESSURE, CHECKING
z Mass Air Flow (MAF) z Check Mass Air Flow (MAF) sensor. See MASS
sensor faulty AIR FLOW (MAF) SENSOR - G70-,
CHECKING
zOxygen sensor zCheck oxygen sensor heating. See OXYGEN
heating faulty SENSOR (O2S) HEATING - Z19- FOR
z Oxygen sensor faulty OXYGEN SENSOR BEFORE THREE WAY
CATALYTIC CONVERTER (TWC),
CHECKING
z Fuel injector does not z See FUEL INJECTORS, CHECKING
open or opens only
partially
z Evaporative Emission z Check Evaporative Emission (EVAP) canister
(EVAP) canister purge regulator valve. See FUEL TANK
purge regulator valve VENTILATION SYSTEM, CHECKING
sticks

Evaluation display group 033

EVALUATION DISPLAY GROUP 033

Display
field: 2 Possible cause Corrective action
larger than z Short circuit to B+ in wire z Check oxygen sensor wiring and oxygen
4.800 V between oxygen sensor and sensor before catalytic converter. See
control module TESTING OXYGEN SENSOR WIRES
z Oxygen sensor faulty

smaller z Replace oxygen sensor

z Short circuit to Ground (GND)
than 0.130 in wire between oxygen sensor
V and control module
z Oxygen sensor faulty

Testing primary voltage

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z Disconnect 6-pin harness connector (black) to Heated Oxygen Sensor (HO2S) -G39-.

Fig. 94: Identifying HO2S 6-Pin Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminal 1 and 5 for voltage measurement.

z Switch ignition on.
z Specification: 0.400 to 0.500 V

z Switch ignition off.

If specified value is not obtained:

z Test oxygen sensor wires.

If specified value is obtained:

z Replace Heated Oxygen Sensor (HO2S) -G39-.

Testing oxygen sensor wires

z Disconnect 4-pin harness connector (black) to oxygen sensor before catalytic converter.
z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .

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Fig. 95: Identifying HO2S 6-Pin Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit.

HO2S CIRCUIT TEST - OPEN CIRCUITS

Harness connector Terminal VAG1598/31 test box Socket
1 70
2 71
5 51
6 52

z Repair open circuit if necessary.

See SYSTEM WIRING DIAGRAMS .

z Check wires to each other for short circuit.

If wire connection is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen Sensor (O2S) aging (HO2S before TWC), checking

Special tools and equipment

z VAG1788/10 RPM adjuster

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Fig. 96: Identifying Special Service Tool (1 Of 2)

Courtesy of AUDI OF AMERICA, INC.

z VAS5051 with VAG5051/1

Fig. 97: Identifying Special Service Tool (2 Of 2)

Courtesy of AUDI OF AMERICA, INC.

Test requirements:

z Coolant temperature at least 80° C.

Test sequence

z Connect vehicle diagnostic, testing and information system VAS 5051. See VAS 5051 VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST),
CONNECTING AND SELECTING FUNCTIONS and select vehicle system "01 -Engine electronics"
in selection. Engine must be run at idle.
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Display on VAS 5051:

Fig. 98: VAS 5051 Scan Tool Display - O2S Aging (HO2S Before TWC), Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "04 - Basic setting".

Display on VAS 5051:

Fig. 99: VAS 5051 Scan Tool Display - O2S Aging (HO2S Before TWC), Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max entered value = 255

z Enter "034" for "display group number 034" in field -2- and confirm entry by pressing -Q- button.
z Set engine speed with V.A.G. 1788/10 RPM adjuster to 1800 -2200/rpm.

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Display on VAS 5051:

Fig. 100: VAS 5051 Scan Tool Display - O2S Aging (HO2S Before TWC), Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check specified value in display field -4-.

NOTE: This process can take several minutes.

DISPLAY GROUP 034: DIAGNOSTIC OXYGEN SENSOR AGING

Display fields
1 2 3 4
Display group 034: Diagnostic oxygen sensor aging
Display xxxx/min xxx° C x.x s ---
Indicated Engine speed Exhaust Period duration Oxygen Diagnostic
(RPM) temperature sensor before condition
Catalytic converter
Functional 0 to 6800 70 to 850° C 0 to 3.0 s Test OFF
range Test ON
B1-S2 OK
B1-S2 not OK
Specified value 1800 to 2200 more than 350° C 0.5 to 2.0 s B1-S2 OK
RPM
Notes If specified value is not obtained, see
CONTINUED

Note for display field 2:

Calculated value from engine speed and engine load.

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Note for display fields 3 and 4:

Period duration is the time between two oxygen sensor voltage jumps (e.g. rich - lean - rich) and is therefore a
measurement of the aging condition of the oxygen sensor. If the specified time is exceeded, display field 4 will
indicate = B1-S1 not OK.

Continued

If specified value in display field 3 and 4 is not obtained:

z Road test vehicle in order to free oxygen sensor of possible residue and repeat test.

If specified value in display field 3 and 4 is not obtained, even after road test:

z Replace Heated Oxygen Sensor (HO2S) - G39-.

Oxygen Sensor (O2S) heating - Z19- for oxygen sensor before Three Way Catalytic Converter (TWC), checking

Special tools and equipment

z V.A.G 1526 A Multimeter

z V.A.G 1594 A Connector test kit
z V.A.G 1598/31 Test box

Fig. 101: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Test requirements:

z Coolant temperature at least 80° C

z Fuse for Oxygen Sensor (O2S) heating OK.

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See SYSTEM WIRING DIAGRAMS .

Test sequence

z Disconnect 6-pin connector (black) -5- to Oxygen Sensor before Three Way Catalytic Converter (TWC) -
G39-.
z Connect multimeter between terminals 3 and 4 to measure resistance.

Fig. 102: Identifying HO2S 6-Pin Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Specified value at room temperature 2.5 to 10 ohm

If specified value is not obtained:

z Replace Oxygen Sensor 1 before Three Way Catalytic Converter (TWC) -G39-.

If specified value is obtained:

z Check voltage supply for oxygen sensor heating

Checking voltage supply for Oxygen Sensor heating

z Connect multimeter between terminals 3 and 4 to measure voltage.

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Fig. 103: Identifying HO2S 6-Pin Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Start engine.
z Specified value: approx. battery voltage (B+)

NOTE: Points at which Oxygen Sensor heating is switched on and off by Engine
Control Module (ECM) can be observed in "Reading measured value block"
function, display group number 041 and display zone 2.

If no voltage is present:

z Connect multimeter as follows to measure voltage.

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Fig. 104: Identifying HO2S 6-Pin Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

HO2S CIRCUIT TEST - VOLTAGE SUPPLY (TERMINAL 3)

Connector terminal Measure to
3 Engine ground (GND)

z Operate starter briefly.

z Specified value: approx. battery voltage (B+)

If no voltage is present:

z Check wiring from terminal 3 on the connector via the fuse to fuel pump relay for an open circuit:

See SYSTEM WIRING DIAGRAMS .

If voltage supply is OK:

z Connect multimeter as follows to measure voltage:

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Fig. 105: Identifying HO2S 6-Pin Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

HO2S CIRCUIT TEST - VOLTAGE SUPPLY (TERMINAL 4)

Connector terminal Measure to
4 (engine control module ground activation) Battery positive (B+)

z Start engine.
z Specified value: approx. battery voltage (B+)

NOTE: Points at which Oxygen Sensor heating is switched on and off by engine
control module can be observed in "Reading measured value block" function,
display group number 041 and display zone 2.

z Switch ignition off.

If no voltage is present:

z Connect test box V.A.G 1598/31 to wiring harness for engine control module; do not connect directly to
Engine Control Module (ECM). See ELECTRICAL TESTING USING VAG1598/31 TEST BOX .
z Check for open circuit in following wiring connections:
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Fig. 106: Identifying HO2S 6-Pin Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

HO2S CIRCUIT TEST - OPEN CIRCUIT

Connector terminal Test box V.A.G 1598/31 Socket
4 5

z Repair open circuit, if necessary.

See SYSTEM WIRING DIAGRAMS .

If wiring is OK but there is no ground for the Oxygen Sensor heating:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen Sensor (O2S) and Oxygen Sensor control before Three Way Catalytic Converter (TWC), checking

NOTE: The Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC) (Bank 1,
sensor 1) changes to Oxygen Sensor 1. If this Oxygen Sensor (O2S) is
damaged, e.g. through contamination or overheating, the control value can be
changed. Deviations from Oxygen Sensor 1 are recorded by the Oxygen Sensor
(O2S) after the Three Way Catalytic Converter (TWC) (Bank 1, sensor 2). If these
deviations are recognized downward or upward it influences the control before
the Three Way Catalytic Converter (TWC) in such a way that it is generally
raised or lowered accordingly.

Special tools and equipment

z V.A.G 1526 A Multimeter

z V.A.G 1594 A Connector test kit
z V.A.G 1598/31 Test box
z VAS 1788/10
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z VAS 5051 with 5051/1

Fig. 107: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Test requirements:

z No leaks in exhaust system

z Coolant temperature at least 80° C.

Test sequence

z Connect vehicle diagnostic, testing and information system VAS 5051. See VAS 5051 VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST),
CONNECTING AND SELECTING FUNCTIONS and select vehicle system "01 -Engine electronics"
in selection. Engine must be run at idle.

Display on VAS 5051:

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Fig. 108: VAS 5051 Scan Tool Display - O2S And O2S Control Before TWC, Checking (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "04 - Basic setting".

Display on VAS 5051:

Fig. 109: VAS 5051 Scan Tool Display - O2S And O2S Control Before TWC, Checking (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

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1. - Enter display group

z Enter "030" for "display group number 030" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:

Fig. 110: VAS 5051 Scan Tool Display - O2S And O2S Control Before TWC, Checking (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Check indication in display group -2-.

NOTE: z By increasing the engine speed the specified values are obtained more
quickly.
z The "Oxygen Sensor status" indicates the condition of the Oxygen Sensor
control and the Oxygen Sensor (O2S).

DISPLAY GROUP 030: OXYGEN SENSOR (O2S) STATUS AT IDLE

Display fields
1 2 3 4
Display group 030: Oxygen Sensor (O2S) status at idle
Display XXX XXX
Display Oxygen Sensor (O2S) status, bank 1, Oxygen Sensor (O2S) status bank 1,
sensor 1 sensor 2
Range 0 = off 0 = off
1 = on 1 = on
Specified 111 110

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value
Note In 4 -digit displays ignore position -1-.
If specified value is not obtained, see OXYGEN SENSOR (O2S) HEATING - Z29-
FOR OXYGEN SENSOR AFTER THREE WAY CATALYTIC CONVERTER
(TWC), CHECKING

SIGNIFICANCE OF 3-DIGIT READOUT OF DISPLAY GROUP 030

Significance of 3-digit readout of display group 030
X X X Display fields 1 and 2:
X Oxygen sensor control 0 = not active; 1 = active
X Oxygen Sensor (O2S) condition: 0 = not active; 1 = active
X Condition of Oxygen Sensor (O2S) heating: 0 = not active; 1 = active

NOTE: z The first digit of the 3-digit display (heating) fluctuates between 0 and 1.
z The Oxygen Sensor control of the Oxygen Sensor (O2S) after Three Way
Catalytic Converter (TWC). (B1 - S2) is inactive without engine load.

Display on VAS 5051:

Fig. 111: VAS 5051 Scan Tool Display - O2S And O2S Control Before TWC, Checking (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Only continue test if display in display field -2- has reached "110" at least once.
z Press <- button.
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Oxygen Sensor control after Three Way Catalytic Converter (TWC), checking

z Set engine speed with VAG 1788/10 RPM adjuster to 2000 RPM.
z Press <- button.

Display on VAS 5051:

Fig. 112: VAS 5051 Scan Tool Display - O2S Control After TWC, Checking (1 Of 2)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

z Enter "037" for "display group number 037" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:

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Fig. 113: VAS 5051 Scan Tool Display - O2S Control After TWC, Checking (2 Of 2)
Courtesy of AUDI OF AMERICA, INC.

z Check Oxygen Sensor (O2S) voltage in display field -2-.

z Check Oxygen Sensor (O2S) correction value in display field -3- and diagnosis result in display field -4-.

DISPLAY GROUP 037: DIAGNOSIS, OXYGEN SENSOR (O2S) CONTROL SYSTEM (BANK 1,
SENSOR 2)
Display fields
1 2 3 4
Display group 037: Diagnosis, Oxygen Sensor (O2S) control system (bank 1, sensor 2)
Display xxx % x.xxx V x.xx ---
Display Engine Oxygen Sensor (O2S) Oxygen Sensor Diagnosis status
load voltage, bank 1, sensor 2 (O2S) voltage
between bank 1,
sensor 1 and
bank 1, sensor 2
Range Test OFF
Test ON
Syst. OK
Syst. NOK
Specified 12 to 0.100...0.950 volts < 0.02 Syst. OK
value 30%
Note If specified value is not If the display shows "Syst. NOK":
obtained: Evaluation. See check DTC memory. See CHECK
EVALUATING DTC MEMORY (SCAN TOOL

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DISPLAY GROUP 037 FUNCTION 02) AND ERASE

DTC MEMORY (SCAN TOOL
FUNCTION 05)

Note on display field 2:

The Oxygen Sensor (O2S) voltage bank 1, sensor 2 should be kept as constant as possible. Strong voltage
fluctuations indicate a damaged Three Way Catalytic Converter (TWC).

Evaluating display group 037

EVALUATING DISPLAY GROUP 037 SPECIFICATION

Display Possible cause Corrective action
field: 2
Constant z Open circuit in line 4 z Check basic voltage. See CONTINUED
approx. between Oxygen Sensor
0.450 V (O2S) and engine control
module (ECM)
z Open circuit in line 3
between Oxygen Sensor
(O2S) and engine control
module (ECM)
Greater than z Short to positive in line 4 z Test Oxygen Sensor wiring, Oxygen Sensor
0.950 V between Oxygen Sensor after Three Way Catalytic Converter (TWC).
(O2S) and engine control See OXYGEN SENSOR WIRING
module (ECM) HARNESS, CHECKING
Less than z Short to ground (GND) in
0.100 V line 4 between Oxygen
Sensor (O2S) and engine
control module (ECM)

Continued

If specification in display field 3 or 4 is not obtained:

z Perform test drive to free Oxygen Sensor (O2S) from any possible residues and repeat test.

If specified value in display field 3 or 4 is not obtained, even after a test drive has been performed:

z Replace Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC).

NOTE: If the Oxygen Sensor (O2S) voltage is OK and after a road test the Oxygen
Sensor correction value is still outside the specification, this indicates aging of
the Oxygen Sensor before the Three Way Catalytic Converter (TWC).

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Checking basic voltage

z Unscrew the protective cover -2- (arrow)

Fig. 114: Oxygen Sensor (O2S) Behind Three Way Catalytic Converter Protective Cover
Courtesy of AUDI OF AMERICA, INC.

z Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) Behind Three Way Catalytic Converter
(TWC) -G130-.
z Connect multimeter between terminals 3 and 4 to measure voltage.

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Fig. 115: Identifying Oxygen Sensor Behind TWC Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Specified value: 0.400...0.500 V

z Switch ignition off.

If specified value is not obtained:

z Check oxygen sensor wiring harness.

If specified value is obtained:

z Replace Oxygen Sensor (O2S) after Three Way Catalytic Converter (TWC) -G130-.

Oxygen sensor wiring harness, checking

z Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) after Three Way Catalytic Converter
(TWC) -G130-.
z Connect test box V.A.G 1598/31 to wiring harness for engine control module; do not connect directly to
Engine Control Module (ECM). See ELECTRICAL TESTING USING VAG1598/31 TEST BOX .
z Check for open circuit in following wiring connections:

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Fig. 116: Identifying Oxygen Sensor Behind TWC Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

O2S BEHIND TWC CIRCUIT TEST - OPENS

Connector terminal Test box V.A.G 1598/31 Socket
3 68
4 69

z Repair open circuit, if necessary.

See SYSTEM WIRING DIAGRAMS .

z Check for shorts between two wires.

If wiring is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING

Oxygen Sensor (O2S) heating - Z29- for Oxygen Sensor after Three Way Catalytic Converter (TWC), checking

Special tools and equipment

z V.A.G 1526 A Multimeter

z V.A.G 1594 A Connector test kit

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z V.A.G 1598/31 Text box

Fig. 117: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Test requirements:

z Coolant temperature at least 80° C.

z Fuse for Oxygen Sensor (O2S) heating OK.

See SYSTEM WIRING DIAGRAMS .

Test sequence

z Unscrew the protective cover -2- (arrow).

z Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) before Three Way Catalytic Converter
(TWC) -G130-.
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Fig. 118: Locating 4-Pin Connector (Brown) To O2S Before TWC

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminals -1- and -2- to measure resistance.

Fig. 119: Identifying Oxygen Sensor Behind TWC Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

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z Specified value at room temperature 6.4 to 47.5 ohm

If specified value is not obtained:

z Replace Oxygen Sensor (O2S) after Three Way Catalytic Converter (TWC) -G130 -.

If specified value is obtained:

z Check voltage supply for oxygen sensor heating

Voltage Supply for Oxygen Sensor Heating

z Connect multimeter between terminals -1- (positive (B+)) and -2- (ground (GND)) to measure voltage.

Fig. 120: Identifying Oxygen Sensor Behind TWC Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Start engine.
z Specified value: approx. battery voltage (B+)

NOTE: Points at which Oxygen Sensor (O2S) heating is switched on and off by Engine
Control Module (ECM) can be observed in "Reading measured value block"
function, display group number 041 and display field 4.

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If no voltage is present:

z Connect multimeter as follows to measure voltage:

Fig. 121: Identifying Oxygen Sensor Behind TWC Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

O2 SENSOR BEHIND TWC CIRCUIT TEST - HEATING VOLTAGE SUPPLY (TEMINAL 1)

Connector terminal Measure to
1 Engine ground (GND)

z Operate starter briefly.

z Specified value: approx. battery voltage (B+)

If no voltage is present again:

z Check wire connection from connector terminal 1 via fuse to fuel pump relay for open circuit:

See SYSTEM WIRING DIAGRAMS .

If voltage supply is OK:

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z Connect multimeter as follows to measure voltage:

Fig. 122: Identifying Oxygen Sensor Behind TWC Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

O2 SENSOR BEHIND TWC CIRCUIT TEST - HEATING VOLTAGE SUPPLY (TEMINAL 2)

Connector terminal Measure to
2 (ground activation by ECM) Battery positive (B+)

z Start engine.
z Specified value: approx. battery voltage (B+), voltage may fluctuate

If no voltage is present:

z Connect test box V.A.G 1598/31 to wiring harness for Engine Control Module (ECM); do not connect to
the ECM. See ELECTRICAL TESTING USING VAG1598/31 TEST BOX .
z Check for open circuit in the following wiring connections:

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Fig. 123: Identifying Oxygen Sensor Behind TWC Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

O2 SENSOR BEHIND TWC CIRCUIT TEST - OPEN CIRCUIT IN HEATER

Connector terminal Test box V.A.G 1598/31 Socket
2 63

z Repair open circuit, if necessary.

If wiring is OK but there is no ground (GND) supply for the Oxygen Sensor (O2S) heating:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen Sensor (O2S), removing and installing

Special tools and equipment

z Box wrench set 3337

z High-temperature lubricant G 052 112 A3

Procedure

z Oxygen sensor after catalytic converter: Remove cover - 2- (arrow).

z Disconnect harness connector of oxygen sensor -1- and lay it to side.

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Fig. 124: Locating Oxygen Sensor Connector

Courtesy of AUDI OF AMERICA, INC.

z Oxygen sensor before catalytic converter: Disconnect harness connector (arrow) and lay it aside.
z Remove oxygen sensor using special tool 3337.

Note the following when installing:

NOTE: z Oxygen sensor threads are coated with an assembly paste. This paste
must not contact sensor openings.
z Tightening torque: 55 Nm
z Oxygen sensor wiring must always be secured in same position when
installing so that contact with the exhaust pipe is avoided.

FUEL TANK VENTILATION SYSTEM, CHECKING

Evaporative Emission (EVAP) canister purge regulator valve -N80-, checking

Special tools and equipment

z VAG1526A
z VAG1527B

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z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

Fig. 125: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Checking for proper seal

Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80- remains closed when de-energized.

z Disconnect hoses from Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80- but leave
electrical connector connected.
z Connect auxiliary hose to one connection of Evaporative Emission (EVAP) Canister Purge Regulator
Valve -N80-.
z Connect vehicle diagnostic, testing and information system VAS 5051 Scan Tool and select "01 - engine
electronics". See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM
OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS . Engine must
be running at idle.
z Initiate final control diagnosis and activate Evaporative Emission (EVAP) Canister Purge Regulator
Valve -N80-. See OUTPUT DIAGNOSTIC TEST MODE (DTM) (SCAN TOOL FUNCTION 03) .

Display on VAS 5051:

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Fig. 126: VAS 5051 Scan Tool Display - EVAP Canister Purge Regulator Valve -N80-, Checking
Courtesy of AUDI OF AMERICA, INC.

A. - 1. Output check diagnosis

1. - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-

z Valve must click...

z ...and must open and close (can be tested by blowing into assisting hose).

If valve does not click:

z Check internal resistance of EVAP valve.

If valve does not open and close properly:

z Replace Evaporative Emission (EVAP) canister purge regulator valve -N80-.

Checking internal resistance

z Disconnect connector at EVAP valve.

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Fig. 127: Checking EVAP Canister Purge Regulator Valve Internal Resistance
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between contacts 1 and 2 at valve for resistance measurement.

z Specification: 22 to 30 ohm

If specified value is not obtained:

z Replace Evaporative Emission (EVAP) canister purge regulator valve -N80-.

If specified value is obtained:

z See CHECKING VOLTAGE SUPPLY .

Checking voltage supply

Test requirement:

z Fuse for Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80- OK.

See SYSTEM WIRING DIAGRAMS .

z Fuel pump relay OK; checking. See FUEL PUMP (FP) RELAY -J17-, CHECKING AND
ACTIVATING .

NOTE: Voltage is supplied to the EVAP valve via the Fuel Pump (FP) relay.

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z Disconnect connector at EVAP valve.

Fig. 128: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1527B voltage tester as follows:

EVAP CANISTER PURGE REGULATOR VALVE VOLTAGE CHECK

Harness connector Terminal Measure to
1 Engine Ground (GND)

z Operate starter briefly (engine may start).

z LED must light up.

If LED does not light up:

z Check wire connection from terminal 1 to Fuel Pump (FP) relay via fuse for open circuit.

See SYSTEM WIRING DIAGRAMS .

z Repair open circuit if necessary.

If LED lights up:

z Check activation.

Checking activation

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z Connect VAG1527B voltage tester to connector terminals 1 (B+) and 2.

Fig. 129: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Initiate output DTM and activate Evaporative Emission (EVAP) canister purge regulator valve -N80-. See
OUTPUT DIAGNOSTIC TEST MODE (DTM) (SCAN TOOL FUNCTION 03) .
z LED must blink.

If LED does not blink or if it remains constantly lit:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:

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Fig. 130: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

EVAP CANISTER PURGE REGULATOR VALVE ACTIVATION CHECK

Harness connector Terminal VAG1598/31 test box Socket
2 64

z Repair open circuit or short circuit if necessary.

If wire connection is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

ELECTRONIC POWER CONTROL (EPC) SYSTEM, CHECKING

EPC system, function

For Electronic Power Control (EPC) system, the throttle valve is not operated by a cable from accelerator pedal.
There is no mechanical connection between accelerator pedal and throttle valve.

The position of accelerator pedal is communicated to Engine Control Module (ECM) via two sensors for
accelerator pedal position (variable resistances; stored in one housing) that are connected with accelerator pedal.

The accelerator pedal position (driver's intention) is a main input unit for ECM.

Operation of throttle valve occurs via an electric motor (throttle valve actuator) in the throttle valve control
module. This is true across the entire engine speed and engine load spectrum.

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The throttle valve is operated by throttle valve actuator according to instructions of the ECM.

With ignition switched on and engine off, the ECM activates throttle valve actuator precisely according to
sensor for accelerator pedal position. This means, if accelerator pedal is depressed half way, the throttle valve
actuator opens the throttle valve to the same degree; i.e. throttle valve would be opened half way.

With engine running (under load), the ECM can open or close throttle valve independently of sensor for
accelerator pedal position.

This means, for example, that the throttle valve could be fully opened even though accelerator pedal has only
been depressed half way. This has the advantage of preventing torque losses at throttle valve.

In addition to this, it results in significantly better values relative to emissions and consumption under certain
load conditions.

The required engine torque can be achieved by Engine Control Module (ECM) via optimal combination of
throttle valve diameter and boost pressure.

It would be incorrect to think that (EPC) consists of only one or two components. The Electronic Power Control
(EPC) system is much more of a system, containing all components that contribute to recognizing, controlling
and monitoring position of throttle valve, e.g. sensor for accelerator pedal position, throttle valve control
module, EPC warning lamp, Engine Control Module (ECM).

Electronic Power Control (EPC) Warning Lamp -K132- (malfunction light for power accelerator activation) in
instrument cluster, significance

NOTE: The malfunction light for power accelerator activation -K132- is also called the
EPC warning lamp.

"EPC" is an abbreviation and stands for Electronic Power Control. This system is also called "E-gas".

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Fig. 131: Locating Of EPC Warning Lamp

Courtesy of AUDI OF AMERICA, INC.

Installation location of EPC warning lamp

Engine Control Module (ECM) checks all components that are important for function of the EPC after ignition
is switched on.

During test of these components, the ECM switches EPC warning lamp on.

If malfunctions are recognized in EPC system during operation of the engine, the ECM switches on EPC
warning lamp in instrument cluster. (These malfunctions are listed in DTC table). An entry is made in DTC
memory at the same time.

EPC warning lamp (fault light for power accelerator activation) -K132-, checking

Functional check of warning lamp

z Switch ignition on.

z Engine Control Module (ECM) switches on the Electronic Power Control (EPC) Warning Lamp -
K132-.
z Start engine.
{ Shortly after starting the engine the exhaust warning lamp goes out if no malfunction in relation to
the EPC is stored in the DTC memory.

NOTE: The switch-on signal for the warning lamp is transferred via CAN-bus to the
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instrument cluster by the Engine Control Module. Check the data exchange
between Engine Control Module (ECM) and other CAN-bus control modules.
See DATA EXCHANGE, MOTRONIC (CAN-bus), CHECKING

Throttle valve control module -J338-, checking

The following components are located in housing for throttle valve control module:

z Throttle drive (power accelerator actuation) - G186-. (This is an electric motor that is activated by ECM.
This electric motor opens throttle valve against spring pressure.)
z Angle sensor -1- for throttle drive (power accelerator actuation) -G187-
z Angle sensor -2- for throttle drive (power accelerator actuation) -G188-

NOTE: z The housing for throttle valve control module must not be opened.
z The angle sensors are designed as potentiometers (variable resistances).
They communicate position of throttle valve to Engine Control Module
(ECM) fully independent of each other.
z The potentiometers cannot be mechanically adjusted. Adjustment is
performed in Basic Setting (function 04) using the VAS5051 tester Scan
Tool.

Throttle valve control module -J338-, adapting

The adaptation teaches Engine Control Module (ECM) various positions of throttle valve when ignition is on
and engine is stopped. These positions are stored in control module The return communication regarding
position of throttle valve occurs via two angle sensors for throttle drive.

An adaptation must always be performed when throttle valve control module -J338- or Engine Control Module
(ECM) are removed and installed (or replaced) or if voltage supply to Engine Control Module (ECM) is
interrupted.

The learning process (adaptation) occurs:

z Automatically if ignition is switched on for at least 6 seconds without operating starter and accelerator
pedal and Engine Control Module (ECM) recognizes "adaptation required". (There will be no notification
of whether adaptation was successful or not however). Adaptation required is recognized if stored voltage
values from angle sensors do not match actual measured voltage values within a certain tolerance range.
z Via initiation of Basic Setting (function 04) display group 60 with ignition on.

NOTE: Engine will not start during automatic adaptation.

Special tools and equipment

z VAS5051 with VAG5051/1

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Fig. 132: Identifying Special Service Tool VAS 5051

Courtesy of AUDI OF AMERICA, INC.

Requirements

z No DTCs in DTC memory, check DTC memory. See CHECK DTC MEMORY (SCAN TOOL
FUNCTION 02) AND ERASE DTC MEMORY (SCAN TOOL FUNCTION 05) .
z Engine not running, ignition switched on.
z Accelerator pedal not depressed.
z Coolant temperature 10° C to 95° C.
z Intake Air Temperature (IAT) 10° C to 90° C.
z Supply voltage for ECM larger than 12.7 V; checking. See VOLTAGE SUPPLY FOR ENGINE
CONTROL MODULE (ECM), CHECKING .

Procedure

z Connect vehicle diagnostic, testing and information system VAS 5051. See VAS 5051 VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST),
CONNECTING AND SELECTING FUNCTIONS and select vehicle system "01 -Engine electronics"
in selection. Ignition must be switched on.

Display on VAS 5051:

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Fig. 133: VAS 5051 Scan Tool Display - Throttle Valve Control Module -J338-, Adapting (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "04 - Basic setting".

Display on VAS 5051:

Fig. 134: IVAS 5051 Scan Tool Display - Throttle Valve Control Module -J338-, Adapting (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max. entered value = 255

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z Enter "060" for "display group number 060" in field -2- and confirm entry by pressing -Q- button.

After pressing the -Q- button, the throttle valve drive is initially connected without voltage present.

In this condition, the throttle valve is pulled into an emergency running position by a mechanical spring which
is located in Throttle Valve Control Module -J338-. The values supplied by two angle sensors in this emergency
running position are stored in Engine Control Module (ECM).

The throttle valve is then opened by a predetermined amount. When this value is reached, the throttle valve
drive is again disconnected from voltage supply. The mechanical spring should then close throttle valve to
previously learned emergency running position within a specified period of time (spring test).

The throttle valve drive then closes throttle valve; values supplied by angle sensors in Throttle Valve Control
Module -J338- are stored in Engine Control Module (ECM).

If Engine Control Module (ECM) disconnects throttle valve drive from voltage supply while vehicle is being
driven, the result will be an increased and fluctuating idling speed and a very poor throttle response.

Display on VAS 5051:

Fig. 135: VAS 5051 Scan Tool Display - Throttle Valve Control Module -J338-, Adapting (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check specifications for Throttle Valve Control Module - J338- in display fields -3- and -4-.

DISPLAY GROUP 060: ADAPTATION OF THROTTLE VALVE CONTROL MODULE

Display fields
1 2 3 4
Display group 060: Adaptation of throttle valve control module
Display xx % xx % --- ---
Indicated Throttle Throttle Adaptation step Adaptation condition
valve valve counter
angle angle
(angle (angle
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sensor 1) sensor 2)
Functional min.: 0 min.: 0 0 through 8 ADP in progress
range % % ADP OK
max.: max.: ADP ERROR
100% 100%
Specified 3 to 93% 97 to 3% 8 ADP OK
value
Notes After adaptation the If "ERROR" is displayed: Check DTC
adaptation stage memory. See CHECK DTC MEMORY
counter reaches (SCAN TOOL FUNCTION 02) AND
figure 8. (Figures ERASE DTC MEMORY (SCAN TOOL
may be skipped) FUNCTION 05) .If specified value is not
obtained: See the following notes.

NOTE: The abbreviation "ADP" in display field 4 stands for "Adaptation".

NOTE: The control module can abort adaptation for the following reasons:

z The throttle valve cannot close completely (e.g. contamination).

z The battery voltage is too low.
z Throttle Valve Control Module -J338- or wire connection is faulty.
z Engine is started during adaptation or accelerator pedal is operated.
z Tension of throttle valve housing (check bolts).

When adaptation process is interrupted, message "Function is unknown or

cannot be carried out at the moment" is displayed on tester. The next time the
ignition is switched on (for several seconds), the adaptation process is
automatically performed again.

z Exit function "04 - Basic setting" by pressing <- button.

Angle sensors for throttle drive, checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

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Fig. 136: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Angle sensor 1 for throttle drive (power accelerator activation) -G187- and angle sensor 1 for throttle drive
(power accelerator activation) - G188- inform the Engine Control Module (ECM) about the position of throttle
valve. Both angle sensors are located in throttle valve control module.

Test sequence

z Connect vehicle diagnostic, testing and information system VAS 5051. See VAS 5051 VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST),
CONNECTING AND SELECTING FUNCTIONS and select vehicle system "01 -Engine electronics"
in selection. Ignition must be switched on.

Display on VAS 5051:

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Fig. 137: VAS 5051 Scan Tool Display - Angle Sensors For Throttle Drive, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "08 - Read measured value block".

Display on VAS 5051:

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Fig. 138: VAS 5051 Scan Tool Display - Angle Sensors For Throttle Drive, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max. entered value = 255

z Enter "062" for "display group number 062" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:

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Fig. 139: VAS 5051 Scan Tool Display - Angle Sensors For Throttle Drive, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check specifications for electronic throttle potentiometer voltages in display fields -1- and -2-.

DISPLAY GROUP 062: E-GAS POTENTIOMETER VOLTAGES

Display fields
1 2 3 4
Display group 062: E-Gas potentiometer voltages
Display xx % xx % xx % xx %
Indicated Throttle valve angle Throttle valve angle Sensor for Sensor 2 for
(angle sensor 1) (angle sensor 2) pedal position pedal position
Specified value 3 to 93% 97 to 3% 12 to 97% 4 to 49%

NOTE: Engine Control Module (ECM) calculates voltage values of angle sensors in
percent relative to 5 volts and displays these percentage values. (5 volts supply
voltage represents 100%).

z Observe display field 1 and 2.

z Slowly depress accelerator pedal completely.

Percent indication in display field 1 must rise uniformly. In the process, the tolerance range of 3 to 93% is not
completely utilized.

Percent indication in display field 2 must decrease uniformly. The tolerance range 97 to 3% is not used
completely during this.

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NOTE: z The reason why the value indicated in display field 1 climbs, while value
indicated in display field 2 decreases, has to do with the fact that the
potentiometers (angle sensors) in Throttle Valve Control Module -J338- run
in opposite directions.
z This means the voltage of angle sensor 1 runs from 0 to 5 volts. (The more
the throttle valve is opened, the larger the voltage; percent indication
climbs).
z The voltage of angle sensor 2 runs from 5 to 0 volts. (The more the throttle
valve is opened, the lower the voltage; the percentage decreases).

z Exit function "08 - Read measured value block" by pressing <- button.

If the displays are not as described:

z Check Throttle Valve Control Module -J338- voltage supply and wiring. See CHECK VOLTAGE
SUPPLY THROTTLE VALVE CONTROL MODULE . Pay particular attention to connectors, which
may be disconnected or corroded.
z Check Throttle Position (TP) sensor 2 -G185-. See THROTTLE POSITION (TP) SENSOR AND
SENDER -2- FOR ACCELERATOR PEDAL POSITION, CHECKING .

Check voltage supply throttle valve control module

z Pull connector (2) off throttle valve control module.

z Switch ignition on.

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Fig. 140: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter for voltage measurement as follows:

THROTTLE VALVE CONTROL MODULE VOLTAGE CHECK

Harness connector Terminal Specified value
2 + Ground (GND) about 5 V
2+6 about 5 V

If specified values are not obtained:

z CHECKING WIRE CONNECTIONS from Engine Control Module (ECM) to throttle valve control
module. See.

Checking wire connections

z Pull connector (2) off throttle valve control module.

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Fig. 141: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:

THROTTLE VALVE CONTROL MODULE CIRCUIT CHECK - OPENS/SHORTS

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Harness connector Terminal VAG1598/31 test box Socket

1 92
2 83
3 117
4 84
5 118
6 91

z Repair open circuit or short circuit if necessary.

If no malfunctions are found in wires:

z Replace throttle valve control module.

Throttle Position (TP) sensor and sender -2- for accelerator pedal position, checking

Special Tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

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Fig. 142: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Both Throttle Position (TP) sensor -G79- and Sender -2- for accelerator pedal position -G185 - are located at the
accelerator pedal and communicate the driver's intentions to the ECM completely independently of each other.
Both sensors are stored in one housing.

Test sequence

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z Connect vehicle diagnostic, testing and information system VAS 5051. See VAS 5051 VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST),
CONNECTING AND SELECTING FUNCTIONS and select vehicle system "01 -Engine electronics"
in selection. Ignition must be switched on.

Display on VAS 5051:

Fig. 143: VAS 5051 Scan Tool Display - TP Sensor And Sender For Accelerator Pedal Position, Checking
(1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "08 - Read measured value block".

Display on VAS 5051:

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Fig. 144: VAS 5051 Scan Tool Display - TP Sensor And Sender For Accelerator Pedal Position, Checking
(2 Of 3)
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Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max. entered value = 255

z Enter "062" for "display group number 062" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:

Fig. 145: VAS 5051 Scan Tool Display - TP Sensor And Sender For Accelerator Pedal Position, Checking
(3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check specifications for electronic throttle potentiometer voltages in display fields -3- and -4-.

DISPLAY GROUP 062: E-GAS POTENTIOMETER VOLTAGES

Display fields
1 2 3 4
Display group 062: E-Gas potentiometer voltages
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Display xx % xx % xx % xx %
Indicated Throttle valve angle Throttle valve angle Sensor for pedal Sensor 2 for pedal
(angle sensor 1) (angle sensor 2) position position
Specified 3 to 93% 97 to 3% 12 to 97% 4 to 49%
value

NOTE: Engine Control Module (ECM) calculates voltage values of angle sensors in
percent relative to 5 volts and displays these percentage values. (5 volts supply
voltage represents 100%).

z Observe display field 3 and 4.

z Slowly depress accelerator pedal completely.

Percent indication in display field 3 must rise uniformly. The tolerance range 12 to 97% is not used completely
during this.

Percent indication in display field 4 must also rise uniformly. In the process, the tolerance range of 4 to 49% is
not completely utilized.

NOTE: The indicated value in display field 3 must always be about twice as large as
value in display field 4.

z Exit function "08 - Read measured value block" by pressing <- button.

If indications do not resemble description:

z Check voltage supply and wire connections of sensor for accelerator pedal position.

Checking voltage supply of Throttle Position (TP) sensor

z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Disconnect harness connector for accelerator pedal position sensor.

z Switch ignition on.
z Connect multimeter for voltage measurement as follows:

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Fig. 146: Identifying Accelerator Pedal Position Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

ACCELERATOR PEDAL POSITION SENSOR CIRCUIT VOLTAGE CHECK

Harness connector Terminal Specified value
1 + Ground (GND) about 5 V
1+5 about 5 V
2 + Ground (GND) about 5 V
2+3 about 5 V

If specified values are obtained:

z Also check signal wires.

If specified values are not obtained:

z Check wire connections from Engine Control Module (ECM) to sensors for accelerator pedal position.

Checking wire connections

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z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:

Fig. 147: Identifying Accelerator Pedal Position Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

ACCELERATOR PEDAL POSITION SENSOR CIRCUIT CHECK - OPENS/SHORTS

Harness connector Terminal VAG1598/31 test box Socket
1 72
2 73
3 36
4 35
5 33
6 34

z Repair open circuit or short circuit if necessary.

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If no malfunctions are found in wires:

z Replace accelerator pedal position sensor.

See ACCELERATOR PEDAL CABLE, SERVICING .

Brake light switch and brake pedal switch, checking

Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

Fig. 148: Checking Wire Connections

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Courtesy of AUDI OF AMERICA, INC.

NOTE: Command from Sender -2- for accelerator pedal position -G185 - (potentiometer)
to Engine Control Module (ECM) for opening throttle valve is suppressed for
safety reasons when brake is pressed. To do so the brake light signal and
Brake Pedal Switch -F47- signal are required in the ECM. If the brakes are
operated when the accelerator pedal is held at a constant position the engine is
immediately reduced to idling speed. Incorrectly adjusted switches may lead to
unwanted regulating actions.

Test sequence

z Connect VAS 5051 scan tool. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND
INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING
FUNCTIONS and select vehicle system "01 -Engine electronics" in selection.

When doing this the ignition must be switched on.

Display on VAS 5051:

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Fig. 149: VAS 5051 Scan Tool Display - Brake Light Switch And Brake Pedal Switch, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "08 - Read measured value block".

Display on VAS 5051 scan tool:

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Fig. 150: VAS 5051 Scan Tool Display - Brake Light Switch And Brake Pedal Switch, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group, max. entered value =255

z Enter "066" for "display group number 066" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051 scan tool:

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Fig. 151: VAS 5051 Scan Tool Display - Brake Light Switch And Brake Pedal Switch, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check Brake Light Switch -F- / Brake Pedal Switch -F47- in display field -2-.

DISPLAY GROUP 066: SIGNALS TO ENGINE CONTROL MODULE (ECM)

Display fields
1 2 3 4
Display group 066: Signals to Engine Control Module (ECM)
Display xxx km/h XXXX xxx km/h XXXX
Indicated ACTUAL Switch positions Specified Switch
speed speed positions
Functional XX00
range XX11
Specified value XX00
(with brake pedal not
operated)
XX11
with brake pedal operated)
Notes Value:
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X = no significance
Switch points slightly offset

z Exit function "08 - Read measured value block" by pressing <- button.

If indications do not resemble description:

Check switch

z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Disconnect harness connector at brake light switch and brake pedal switch.
z Connect multimeter between terminal 1 and 4 for resistance measurement.

Fig. 152: Identifying Brake Light Switch/Brake Pedal Switch Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

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z Specification: INFINITY ohm (no continuity)

z Depress accelerator pedal.
z Specification: approx. 0 ohm

z Connect multimeter between terminal 2 and 3 for resistance measurement.

z Specification: approx. 0 ohm

z Depress accelerator pedal.

z Specification: INFINITY ohm (no continuity)

If specified values are not obtained:

z Replace brake light switch / brake pedal switch.

If specified values are obtained:

Checking voltage supply

z Connect VAG1527B voltage tester as follows:

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Fig. 153: Identifying Brake Light Switch/Brake Pedal Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH VOLTAGE CHECK (TERMINAL 1)

Harness connector Terminal Measure to
1 Chassis Ground (GND)

z LED must light up.

BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH VOLTAGE CHECK (TERMINAL 2)

Harness connector Terminal Measure to
2 Chassis Ground (GND)

z Switch ignition on.

z LED must light up.

If LED does not light up:

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z Check wire connection from terminal 1 or 2 of connector for open circuit and short circuit to Ground
(GND):

See SYSTEM WIRING DIAGRAMS .

z Repair open circuit or short circuit if necessary.

If LED lights up:

Checking activation

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .

Fig. 154: Identifying Brake Light Switch/Brake Pedal Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:

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BRAKE LIGHT SWITCH/BRAKE PEDAL SWITCH CIRCUIT CHECK - ACTIVATION

Harness connector Terminal VAG1598/31 test box Socket
3 55
4 56

z Repair open circuit or short circuit if necessary.

Clutch vacuum vent valve switch -F36-, checking

Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

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Fig. 155: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

NOTE: This signal helps prevent excessive RPM oscillations and tip-in shocks when
clutch is disengaged and is required for the cruise control system.

Test sequence

z Connect VAS 5051 scan tool. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND
INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING
FUNCTIONS and select vehicle system "01 -Engine electronics" in selection.

When doing this the ignition must be switched on.

Display on VAS 5051 scan tool:

Fig. 156: VAS 5051 Scan Tool Display - Clutch Vacuum Vent Valve Switch, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "08 - Read measured value block".
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Display on VAS 5051:

Fig. 157: VAS 5051 Scan Tool Display - Clutch Vacuum Vent Valve Switch, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

- Enter display group

z Enter "066" for "display group number 066" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:

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Fig. 158: VAS 5051 Scan Tool Display - Clutch Vacuum Vent Valve Switch, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check indication in display field -2-.

DISPLAY GROUP 066: SIGNALS TO ENGINE CONTROL MODULE (ECM)

Display fields
1 2 3 4
Display group 066: Signals to Engine Control Module (ECM)
Display xxx km/h XXXX xxx km/h XXXX
Indicated ACTUAL speed Switch positions Specified speed Switch positions
Functional range X0XX
X1XX
Specified value X0XX
(at clutch pedal not operated)
X1XX
(at clutch pedal operated)
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Notes Value:
X = no significance

z Exit function "08 - Read measured value block" by pressing <- button.

If indications do not resemble description:

Checking switch

z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Disconnect harness connector at Clutch Pedal Position (CPP) switch.

z Connect multimeter between terminal 2 and 3 for resistance measurement.

Fig. 159: Locating Clutch Pedal Position Connector Terminals

Courtesy of AUDI OF AMERICA, INC.
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z Specification: approx. 0 ohm

z Depress clutch pedal.
z Specification: INFINITY ohm(no continuity)

If specified value is not obtained:

z Replace Clutch Pedal Position (CPP) switch.

If specified value is obtained:

z Check voltage supply for Clutch Pedal Position (CPP) switch.

Checking voltage supply

z Connect VAG1527B voltage tester as follows:

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Fig. 160: Identifying Clutch Pedal Position Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

CLUTCH PEDAL POSITION SWITCH CIRCUIT VOLTAGE CHECK

Harness connector Terminal Measure to
1 Chassis Ground (GND)

z Switch ignition on.

z LED must light up.

If LED does not light up:

z Check wire connection from terminal 2 of connector to fuse holder for open circuit and short circuit to
Ground (GND):

See SYSTEM WIRING DIAGRAMS .

z Repair any open/short circuit as necessary.

If LED lights up:

z Check activation of Clutch Pedal Position (CPP) switch.

Checking activation

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:

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Fig. 161: Identifying Clutch Pedal Position Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

CLUTCH PEDAL POSITION SWITCH ACTIVATION CHECK

Harness connector Terminal VAG1598/31 test box Socket
3 39

z Repair open circuit or short circuit if necessary.

ADDITIONAL SIGNALS, CHECKING

Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1
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Fig. 162: Identifying Special Service Tool

Courtesy of AUDI OF AMERICA, INC.

Engine speed (RPM) signal, checking

NOTE: The signal is generated from terminal 37 of the ECM. The engine speed signal is
displayed on the tachometer in the instrument cluster.

z Connect test box V.A.G 1598/31 to wiring harness for Engine Control
Module (ECM); do not connect Engine Control Module (ECM). See
ELECTRICAL TESTING USING VAG1598/31 TEST BOX .
z Check for open circuit and short to positive (B+) or ground (GND) in
following wiring connections:

ENGINE SPEED (RPM) SENSOR CIRCUIT CHECK - OPENS/SHORTS

Test box
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V.A.G 1598/31 Instrument cluster:

Socket terminal
37 See SYSTEM WIRING DIAGRAMS .

z Repair any open/short circuit as needed.

Vehicle Speed Sensor (VSS) signal, checking

NOTE: z The vehicle speed signal is generated by the Speedometer Vehicle Speed
Sensor (VSS) - G22- (at transmission) and processed in the instrument
cluster.
z The processed signal enters at terminal 54 of the ECM and is used for idle
stabilization and tip-in shock reduction during shifting.

Test requirement:

z Function and display of speedometer OK.

Test sequence

WARNING: To reduce the danger of accident during road tests, always observe
safety precautions. See SAFETY PRECAUTIONS .

z Connect VAS5051 scan tool and select control module for engine electronics using "address word" 01.
See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR VAG
1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS . Engine must run at idle
for this.

Display on VAS 5051:

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Fig. 163: VAS 5051 Scan Tool Display - VSS Signal, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Select from the display -1- the diagnostic function "08 - Read Measuring Value Block".

Display on VAS 5051:

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Fig. 164: VAS 5051 Scan Tool Display - VSS Signal, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

- Enter display group, max. entered value = 255

z Enter "005" for "display group number 005" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051

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Fig. 165: VAS 5051 Scan Tool Display - VSS Signal, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Determining via road test whether vehicle speed is displayed in display field 3.
z If vehicle speed is not displayed, lift vehicle -if possible using a vehicle lift- until front left wheel is free.
z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Connect VAG1527B voltage tester to sockets 3 (B+) and 54 (VSS) of VAG1598/31 test box.
z Switch ignition on and turn front left wheel by hand.
z LED must blink (very brief blink signal).

If LED does not blink:

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z Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:

VSS CIRCUIT CHECK - OPENS/SHORTS

Test box
VAG1598/31 Instrument cluster
Socket Terminal
54 See SYSTEM WIRING DIAGRAMS .

z Repair open circuit or short circuit if necessary.

A/C compressor shut-off, checking

NOTE: z The A/C compressor signal communicates to ECM that compressor will be
switched on in 140 ms.
z The ECM can switch off the A/C compressor via same wire connection.
z Engine Control Module (ECM) switches off A/C compressor:
{ - during hard acceleration (Wide Open Throttle 1st gear)

{ - in emergency mode (emergency operation)

{ - after initiating basic setting (function 04)

Test requirements:

z A/C system OK
z No DTCs in DTC memory of Engine Control Module (ECM).
z Vehicle at room temperature (warmer than +15°C).

Test sequence

z Connect VAS5051 scan tool and select the control module for engine electronics using "address word"
01. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR
VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS . Engine must run
at idle for this.

Display on VAS 5051:

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Fig. 166: VAS 5051 Scan Tool Display - A/C Compressor Shut-Off, Checking (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z In field -1- select "08 - Read Measuring Value Block".

Display on VAS 5051:

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Fig. 167: VAS 5051 Scan Tool Display - A/C Compressor Shut-Off, Checking (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

- Enter display group, max. entered value = 255

z Enter "050" in field -2- to select "display group number 050" and press -Q- button to confirm input.

Display on VAS 5051:

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Fig. 168: VAS 5051 Scan Tool Display - A/C Compressor Shut-Off, Checking (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Switch A/C system off.

z Specified value in display field 4: Compr. OFF

z Switch A/C system on using "Auto" button and adjust A/C system to maximum cooling or heating power.
Compressor must run.
z Specified value in display field 4: Compr. ON

z Depress gas pedal completely (swiftly) in first gear during a road test and then release it (brief
acceleration).

Display on VAS 5051:

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Fig. 169: VAS 5051 Scan Tool Display - A/C Compressor Shut-Off, Checking (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Specified value in display field 4: Indication jumps for several seconds from "Compr. ON" to "Compr.
OFF" (compressor shut -off for vehicle acceleration)

If indications in field 4 do not resemble description:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Check the following wire connection for open circuit and short circuit to Ground (GND) and B+:

A/C COMPRESSOR SHUT-OFF CIRCUIT TEST - OPENS/SHORTS

Test box VAG1598/31 Socket A/C control head -E87- Terminal
41 See SYSTEM WIRING DIAGRAMS .

z Repair open circuit or short circuit if necessary.

z If there are no malfunctions in the wiring, check function of A/C system.

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See ON BOARD DIAGNOSTIC (OBD) .

Pressure switch/power steering -F88-, checking

The pressure switch for power steering is used for idle stabilization when steering is turned to full stop (left or
right).

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select the control module for engine electronics
using "address word" 01. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND
INFORMATION SYSTEM OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING
FUNCTIONS . Engine must run at idle for this.

z Display on VAS 5051:

Fig. 170: VAS 5051 Scan Tool Display - Pressure Switch/Power Steering, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z In field -1- select "08 - Read Measuring Value Block".

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Display on VAS 5051:

Fig. 171: VAS 5051 Scan Tool Display - Pressure Switch/Power Steering, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

- Enter display group, max. entered value = 255

z Enter "056" to select "display group number 056" and press -Q- button to confirm input.

Display on VAS 5051:

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Fig. 172: VAS 5051 Scan Tool Display - Pressure Switch/Power Steering, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check pressure switch/power steering in display field -4-.

DISPLAY GROUP 056: IDLE STABILIZATION WITH ENGINE AT IDLE AND OPERATING
TEMPERATURE
Display fields
1 2 3 4
Display group 056: Idle stabilization with engine at idle and operating temperature
Display xxx /min xxx /min x.x % XXXXX
Indicated Engine speed Engine speed Idle Operating conditions
(actual) (specified) control
Torque
change
Functional 0XXXX
range 1XXXX
Specified 0XXXX (with steering straight-ahead
value or slightly off center)

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1XXXX (with steering wheel at end

position)
Notes Value:
X = no significance

If indications do not resemble description:

Check switch

z Disconnect harness connector at Pressure switch/power steering -F88 -, at power steering pump.

Fig. 173: Disconnecting Harness Connector At Pressure Switch/Power Steering

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter at switch for resistance measurement.

z Start engine.
z Specification: INFINITY ohm(no continuity)

z Turn steering as far to right or left as possible.

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z Specification: approx. 0 ohm

If reading does not change:

z Replace pressure switch/power steering -F88 -.

If indication changes:

z See CHECKING WIRE CONNECTIONS .

Checking wire connections

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See ELECTRICAL
TESTING USING VAG1598/31 TEST BOX .
z Check the following wire connections for open circuit and short circuit to Ground (GND) and B+:

Fig. 174: Identifying Pressure Switch/Power Steering Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

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PRESSURE SWITCH/POWER STEERING CIRCUIT TEST - OPENS/SHORTS

Harness connector Terminal VAG1598/31 test box Socket
1 49
2 50

z Repair open circuit or short circuit if necessary.

Crash signal, checking

The Engine Control Module (ECM) receives crash signal ("Crash cut -off was triggered") from airbag control
module.

The airbag control module sends crash signal to Engine Control Module (ECM) (during an accident or if a
Output Diagnostic Test Mode (DTM) is carried out relating to airbag system), the ECM switches off fuel pump.
This means the engine will stop running but can be started again afterward (e.g. to remove vehicle from
danger).

z Connect test box V.A.G 1598/31 to wiring harness for Engine Control Module (ECM); do not connect
test box directly to Engine Control Module (ECM). See ELECTRICAL TESTING USING
VAG1598/31 TEST BOX .
z Check for open circuit and short to positive (B+) or ground (GND) in following wiring connections:

CRASH SIGNAL CIRCUIT TEST - OPENS/SHORTS

Test box V.A.G 1598/31
Socket Airbag Control Module -J234 - terminal
67 See SYSTEM WIRING DIAGRAMS .

z Repair any open/short circuit as necessary.

See SYSTEM WIRING DIAGRAMS .

If no problems with wires are found:

z Check DTC memory of Airbag Control Module - J234-.

See AIR BAG RESTRAINT SYSTEMS .

Consumption signal for board computer, checking

NOTE: The consumption signal is transmitted via CAN - Bus by the ECM to the
instrument cluster. Checking data exchange between the ECM and other
modules on the CAN-Bus. See ELECTRICAL TESTING USING VAG1598/31 TEST
BOX .

Wiring for fuel level signal, checking

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NOTE: z The signal serves to determine the cause of certain recognized failures
(e.g. engine misfires).
z The fuel level signal is transmitted via CAN-bus by the instrument cluster
to the ECM. Checking data exchange between the ECM and other modules
on the CAN-Bus. See DATA EXCHANGE, MOTRONIC (CAN-bus),
CHECKING .

Data exchange, Motronic (CAN-bus), checking

NOTE: z Data exchange between individual control modules occurs via a bus
system.
z The term "CAN-Bus" refers to a system that transports and distributes
data.
z The wire connections between the control modules, via which data is
transferred, are referred to as data wires.
z Data is transferred to the connected control modules serially, one after the
other, across the data wires (e.g. engine speed, Gas pedal setting).

Checking bus system

The DTC table suggested checking data exchange between engine control module (ECM) and other CAN-Bus
modules.

z Connect VAS 5051. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS
and select vehicle system "01 -Engine electronics" in selection. The ignition must be turned on.

Display on VAS 5051:

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Fig. 175: VAS 5051 Scan Tool Display - Checking Bus System (1 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "08 - Read measured value block".

Display on VAS 5051:

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Fig. 176: VAS 5051 Scan Tool Display - Checking Bus System (2 Of 5)
Courtesy of AUDI OF AMERICA, INC.

- Enter display group

NOTE: The measured value blocks 125 and 126 indicate CAN drive users.

z Enter "125" for "display group number 125" in field -2- and confirm entry by pressing -Q- button.

Display on VAS 5051:

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Fig. 177: VAS 5051 Scan Tool Display - Checking Bus System (3 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Check displays in fields -1- to -4-.

CAN-bus compatible control modules are displayed with Engine Control Module:

z No display: Engine Control Module not CAN-compatible

z Display 1: CAN-compatible control module is a data bus user

z Display 0: CAN able control module is not user of the Databus

z To switch to display group 126 press UP ARROW button.

z Check in same way with display group 126.
z Exit function "08 - Read measured value block" by pressing <- button.

Display on VAS 5051:

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Fig. 178: VAS 5051 Scan Tool Display - Checking Bus System (4 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "06 - End output".

Display on VAS 5051:

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Fig. 179: VAS 5051 Scan Tool Display - Checking Bus System (5 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Under -1- select diagnostic function "00 - Check DTC memory - Total system".
z The DTC memory is then checked for all systems in the vehicle which are capable of On Board
Diagnostic (OBD).

If a control module answers with its identification, the number of DTCs stored or "No DTCs detected" appears
on the display.

Any system DTCs that are stored are displayed successively. The VAS 5051 will then transmit the next address
word.

If a DTC is displayed relating to "Data bus drive" or "...CAN bus":

z Check that Engine Control Module (ECM) and other CAN-compatible control modules installed are
suitable for this vehicle (part no. and code).

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If the correct control modules are installed:

z Check that multiple connectors for control modules are properly seated.

If the multi-pin connectors are firmly seated:

z Check CAN bus system.

Checking a "Two-line Bus system"

The following systematic procedure is useful for troubleshooting if three or more control modules are
communicating via a "two -line bus system":

z Evaluate DTCs stored in control modules.

NOTE: This analysis will help you locate the cause of the line malfunction.

Example 1:

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Fig. 180: Schematic - Control Module 1 Does Not Communicate With Control Modules 2 And 3
Courtesy of AUDI OF AMERICA, INC.

The DTCs stored in the DTC memory indicates the control module 1 does not communicate with control
modules 2 and 3.

CONTROL MODULE 1 DOES NOT COMMUNICATE WITH CONTROL MODULES 2 AND 3

Control module DTCs stored in DTC memory
1 z No message from control module 2

z No message from control module 3

2 z No message from control module 1
3 z No message from control module 1

z Switch ignition off.

z Disconnect control modules connected across bus wires and check bus wires for an open circuit.

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See SYSTEM WIRING DIAGRAMS .

z Replace control module 1 if no malfunctions can be found in bus wires.

Example 2:

Fig. 181: Schematic - Control Module 2 Is Not Communicating With Control Modules 1 And 3
Courtesy of AUDI OF AMERICA, INC.

From the DTCs stored in memories, you have determined that control module 2 is not communicating with
control modules 1 and 3.

CONTROL MODULE 2 IS NOT COMMUNICATING WITH CONTROL MODULES 1 AND 3

Control module DTCs stored in DTC memory
1 z No message from control module 2

2 z No message from control module 1

z No message from control module 3
3 z No message from control module 2

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z Switch ignition off.

z Disconnect control modules connected across bus wires and check bus wires for an open circuit.

See SYSTEM WIRING DIAGRAMS .

z Replace control module 2 if no malfunctions can be found in bus wires.

Example 3:

Using the DTCs stored in the memories, you have determined that none of the control modules are sending or
receiving signals.

CONTROL MODULES ARE NOT SENDING OR RECEIVING SIGNALS

Control module DTCs stored in DTC memory
1 z Powertrain data bus malfunction

2 z Powertrain data bus malfunction

3 z Powertrain data bus malfunction

z Switch ignition off.

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Fig. 182: Schematic - Checking For Shorts To Power/Ground On Bus Wires

Courtesy of AUDI OF AMERICA, INC.

z Disconnect control modules connected across bus wires and check for a short circuit between bus wires.

See SYSTEM WIRING DIAGRAMS .

If you cannot determine a cause for the DTC "Powertrain databus malfunction," check whether DTC is
caused by one of control modules

Test requirements:

z Vehicle diagnosis, measurement and information system VAS 5051 connected and vehicle self-diagnosis
selected. See VAS 5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM OR
VAG 1551 SCAN TOOL (ST), CONNECTING AND SELECTING FUNCTIONS .

All control modules that use CAN-bus are still disconnected.

Switch ignition off.

z Connect one of control modules.

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Connect VAS 5051.

Fig. 183: VAS 5051 Scan Tool Display

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Press appropriate vehicle system in selection -1-.
z Check DTC memory of control module you just connected and erase it.
z Press <- button.
z Press diagnostic function "06 - End Output" in selection - 1-.
z Switch ignition off and on again.
z Leave ignition switched on for 10 seconds. Then read DTC memory of control module you just connected
using Scan Tool (ST).
z If DTC "Powertrain CAN-bus malfunction" is displayed, replace control module you just connected.
z If DTC "Powertrain CAN-bus malfunction" is not displayed, connect next control module and repeat
procedure.

VACUUM DIAGRAM

NOTE: The following list refers to items in Fig. 184 .

1. - From fuel tank

2. - EVAP canister
z with Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-

3. - Check-valve for EVAP canister

z Between EVAP canister and intake manifold before turbocharger

z Installation position (light/dark side): Arrow points in direction of flow, as shown

4. - Turbocharger
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5. - Pressure unit for boost pressure regulation

6. - Mechanical recirculation valve
7. - Brake booster
8. - Check-valve
z Between brake booster and intake manifold

z Installation position (light/dark side): Arrow points in direction of flow, as shown

9. - Wastegate bypass regulator valve -N75-

10. - Mass Air Flow (MAF) sensor -G70-
11. - Air cleaner housing
12. - Pressure control valve for crankshaft housing ventilation
13. - Vacuum reservoir
z Bolted on at cylinder head

14. - Charge air cooler

z With charge air pressure sensor -G31-

15. - Fuel pressure regulator

16. - Throttle valve control module -J338 -
17. - Intake manifold
z With Intake Air Temperature (IAT) sensor -G42-

18. - Crankcase ventilation

19. - Check-valve
z Installation position (light/dark side): Arrow points in direction of flow, as shown

20. - Recirculating valve for turbocharger -N249-

z Component location. See INSTALLATION POSITION: RECIRCULATING VALVE FOR
TURBOCHARGER -N249-
21. - Check-valve
z Between EVAP canister and intake manifold

z Installation position (light/dark side): Arrow points in direction of flow, as shown

22. - Charge air cooler

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Fig. 184: Engine Vacuum Diagram

Courtesy of AUDI OF AMERICA, INC.

Installation position: recirculating valve for turbocharger -N249-

z Installation location: On cylinder head cover

NOTE: The following list refers to items in Fig. 185 .

1. - To connection at intake manifold

2. - Vacuum reservoir
3. - To mechanical recirculating valve
4. - Recirculating valve for turbocharger -N249-

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Fig. 185: Identifying Recirculating Valve For Turbocharger -N249-

Courtesy of AUDI OF AMERICA, INC.

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2000-2004 ENGINE PERFORMANCE

Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

MULTIPORT FUEL INJECTION (MFI)

MOTRONIC MULTIPORT FUEL INJECTION AND IGNITION SYSTEM, REPAIRING

Scan Tool (ST) and test equipment safety precautions

To reduce the risk of personal injury and/or damage to the fuel injection and ignition systems, always observe
the following:

z Always switch off ignition before disconnecting or connecting lines of the fuel injection and ignition
system, including test leads.
z If engine is to be cranked at starting RPM without starting (for example, for compression testing),
disconnect connectors from ignition coils and from fuel injectors.
z It is possible that a control module will recognize a malfunction and store a DTC during some tests. After
completing all tests and repairs, DTC memory should therefore be checked and erased if necessary.
z Always switch ignition off before cleaning engine.
z Always switch ignition off before disconnecting or connecting battery. Failure to do so may damage the
Engine Control Module (ECM).

If special testing equipment is required during road test, note the following:

WARNING: z Due to weight, size and need for manual operation of test
instruments while vehicle is driven on public roads, instrument must
be used only with a Driver operating the vehicle and an Instrument
Operator operating the test equipment.
z Do not use Instrument with Driver only. Always use two persons to
conduct test.
z Do not place Instrument on lap of Driver or front seat passenger
because emergency stop may dislodge Instrument and cause airbag
deployment with risk of injury to Instrument Operator.

WARNING: Use of Instrument in Audi TT Coupe:

z Place Instrument in rear seating area and secure by available safety

belt.
z Instrument Operator must be seated in the other rear seating
position, after sliding front passenger seat and moving the seat back
as far forward as possible. Do not activate the seat back release
lever.

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z Instrument Operator must wear safety belt.

Use of Instrument in Audi TT Roadster:

z Use only Instrument VAG 1551 Scan Tool (ST). DO NOT USE VAS
5051.
z Before test, deactivate passenger's airbag using key operated
switch in glove compartment or via OBD program.
z Instrument Operator must be seated on passenger seat with safety
belt worn.
z Place Instrument in foot well in front of passenger seat in a manner
allowing the Operator to use the Instrument in a safe manner.
z After completion of test, re-activate front passenger airbag.

Rules of cleanliness

When working on the fuel supply/injection system, pay careful attention to the following rules of cleanliness:

z Thoroughly clean all connections and the surrounding area before disconnecting.
z Place parts that have been removed on a clean surface and cover. Do not use fluffy cloths!
z Carefully cover over opened components or seal, if repairs are not carried out immediately.
z Only install clean components: Only unpack replacement parts immediately prior to installation. Do not
use parts that have been stored loose (in tool boxes etc.).
z When the system is open: Do not work with compressed air if it can be avoided. Do not move vehicle
unless absolutely necessary.
z Disconnected electrical harness connectors must be protect from dirt and moisture
z Make sure harness connectors are dry before connecting.

Technical data

TECHNICAL DATA
Engine identification ATC (1.8L/5V/Turbo 132 kW -engine)
Idle speed 800 - 920 RPM (manual transmission, Front Wheel
Engine speed cannot be adjusted, it is regulated by Drive -FWD-)
idle stabilization 720 - 840 RPM (manual transmission, All Wheel
Drive -AWD-)
640 - 760 RPM (automatic transmission, Front
Wheel Drive -FWD-)
Engine speed (RPM) limitation approx. 6800 RPM
via fuel injector shut-off
Fuel pressure at idle Vacuum hose connected approx. 2.5 bar positive pressure
speed Vacuum hose disconnected approx. 3.0 bar positive pressure
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Residual pressure after 10 min. minimum 1.5 bar positive pressure

Fuel injectors Injection stream Dual-hole nozzle / same for all injectors
Injection quantity (30 s) 145 +/- 12 ml
Resistance (room 12 - 13 ohm
temperature)
Spark plugs Replacement Part No. 101 000 063 AA (NGK)
Manufacturer code PFR6Q (NGK)

Component locations, overview

The following list pertains to Fig. 1 .

1. - Leak Detection Pump (LDP) - V144-

z Below wheel housing, front, left

2. - Bank 1 sensor 1 (oxygen sensor before catalytic converter), with oxygen sensor heating; Bank 2
sensor 2 (oxygen sensor behind catalytic converter), with oxygen sensor heating;
z Both oxygen sensors and their related harness connectors are accessible from below after vehicle is
raised
z Component location of oxygen sensors, see OXYGEN SENSORS AND PROTECTIVE COVER

z Component location of harness connectors for oxygen sensors, see BLACK AND BROWN
CONNECTORS
3. - Camshaft Position (CMP) sensor 2 -G163 -
4. - Fuel injectors -N30 through N33-
5. - Motronic Engine Control Module (ECM) -J220-
6. - Ignition coils -N-, -N128-, - N158-, -N163-
7. - Wastegate Bypass Regulator Valve -N75-
z Checking:

See CHARGE AIR PRESSURE CONTROL VALVE -N75-, TESTING .

8. - Throttle Position (TP) sensor-G79- and sender -2- for accelerator pedal position -G185-
z Component location, see COMPONENT LOCATIONS OF THROTTLE POSITION (TP)
SENSOR -G79- AND SENDER 2 FOR ACCELERATOR PEDAL POSITION -G185-
9. - Brake light switch -F- and brake pedal switch -F47 -
z Component location, see COMPONENT LOCATION BRAKE LIGHT SWITCH -F- AND
BRAKE PEDAL SWITCH -F47-
10. - Clutch vacuum vent valve switch -F36 -
z Component location, see COMPONENT LOCATION, CLUTCH VACUUM VENT VALVE
SWITCH -F36-
11. - Exhaust warning lamp -K83-
z Component location, see COMPONENT LOCATION, EXHAUST WARNING LAMP -K83- .

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12. - Malfunction light for power accelerator activation -K132-

z "EPC" warning lamp

z Component location, see COMPONENT LOCATION, MALFUNCTION LIGHT FOR

POWER ACCELERATOR ACTIVATION -K132-
13. - Secondary Air Injection (AIR) pump relay -J299-
z Under a black, synthetic cover; directly behind Mass Air Flow (MAF) sensor

14. - Mass Air Flow (MAF) sensor -G70-

15. - Engine Coolant Temperature (ECT) sensor -G62-
16. - Fuel pressure regulator
17. - Speedometer Vehicle Speed Sensor (VSS) -G28-
18. - Knock Sensor (KS) 2 -G66-
19. - Turbocharger boost pressure recirculation valve -N249-
20. - 3-pin harness connector
z pieces

z Component location, see COMPONENT LOCATION, 3-PIN HARNESS CONNECTORS

z For Knock Sensor (KS) 1 - G61-

z For Engine Speed (RPM) sensor -G28-

z For Knock Sensor (KS) 2 - G66-

21. - Secondary Air Injection (AIR) solenoid valve -N112-

22. - Knock Sensor (KS) 1 -G61-
23. - Intake Air Temperature (IAT) sensor -G42-
24. - Secondary Air Injection (AIR) pump motor -V101-
z Checking:

See SECONDARY AIR SYSTEM, COMPONENTS AND FUNCTION .

25. - Pressure switch/power steering -F88 -

z Component location, see COMPONENT LOCATION, PRESSURE SWITCH/POWER
STEERING -F88-
26. - Throttle valve control module -J338 -
z With throttle drive (power accelerator actuation) -G186 -, angle sensor -1- for throttle drive (power
accelerator actuation) -G187- and angle sensor -2- for throttle drive (power accelerator actuation) -
G188-
27. - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
28. - Charge air pressure sensor - G31-
z Component location: Screwed in, above in charge air cooler

z Checking:

See CHARGE AIR PRESSURE SENSOR -G31-, TESTING .

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z Headlight must be removed in order to access charge air pressure sensor.

See HEADLIGHTS or HEADLIGHTS WITH HIGH INTENSITY GAS DISCHARGE (HID)

LAMPS .

Fig. 1: Identifying Multiport Fuel Injection (MFI) Component Locations

Courtesy of AUDI OF AMERICA, INC.

Oxygen sensors and protective cover

Item 1 : Bank 1 sensor 1 (oxygen sensor before catalytic converter) with oxygen sensor heating

Item 2 : Protective cover of oxygen sensor connector for both oxygen sensors

Item 3 : Bank 1 sensor 2 (oxygen sensor behind catalytic converter) with oxygen sensor heating
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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

4-pin harness connectors for both oxygen sensors and oxygen sensor heating are accessible at vehicle floor after
unscrewing protective cover (arrows).

Fig. 2: Identifying Oxygen Sensors And Protective Cover

Courtesy of AUDI OF AMERICA, INC.

Black and brown connectors

Black connector: Harness connector for bank 1 sensor 1 (oxygen sensor before catalytic converter) and
oxygen sensor heating

Brown connector: Harness connector for bank 1 sensor 2 (oxygen sensor behind catalytic converter) and
oxygen sensor heating

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Fig. 3: Locating Black And Brown HO2S Connectors

Courtesy of AUDI OF AMERICA, INC.

Component locations of Throttle Position (TP) sensor -G79- and sender 2 for accelerator pedal position -G185-

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Fig. 4: Locating Component Locations Of Throttle Position (Tp) Sensor -G79- And Sender Accelerator
Pedal Position -G185 -
Courtesy of AUDI OF AMERICA, INC.

Component location brake light switch -F- and brake pedal switch -F47-

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Fig. 5: Locating Component Location Brake Light Switch -F and Brake Pedal Switch -F47 -
Courtesy of AUDI OF AMERICA, INC.

Component location, exhaust warning lamp -K83-

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Fig. 6: Exhaust Warning Lamp - K83- (MIL)

Courtesy of AUDI OF AMERICA, INC.

Component location, malfunction light for power accelerator activation -K132-

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Fig. 7: Malfunction Light For Power Accelerator Activation -K132-

Courtesy of AUDI OF AMERICA, INC.

Component location, clutch vacuum vent valve switch -F36-

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Fig. 8: Locating Clutch Vacuum Vent Valve Switch -F36 -

Courtesy of AUDI OF AMERICA, INC.

Component location, 3-pin harness connectors

1. - For Knock Sensor (KS) 1 -G61-

2. - For speedometer Vehicle Speed Sensor (VSS) -G28-
3. - For Knock Sensor (KS) 2 -G66-

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Fig. 9: 3 -Pin Harness ConnectorLocations

Courtesy of AUDI OF AMERICA, INC.

Component location, pressure switch/power steering -F88-

Fig. 10: Locating Pressure Switch/Power Steering -F88 -

Courtesy of AUDI OF AMERICA, INC.

Air filter, disassembling and assembling

The following list pertains to Fig. 11 .

1. - Seal
2. - Mass Air Flow (MAF) sensor -G70-
3. - Phillips-head screw
4. - Air guide
5. - 5-pin harness connector
6. - Phillips-head screw
7. - Air filter, upper portion
8. - Filter element
9. - Nut -10 Nm
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10. - Air intake connection

11. - Air filter, lower portion
12. - Hex-bolt (10 Nm)

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Fig. 11: Exploded View Of Air Filter Assembly

Courtesy of AUDI OF AMERICA, INC.
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Wire and component test using VAG1598/31 test box

z If the Engine Control Module (ECM) is equipped with a metal anti -theft housing (for theft prevention),
the metal anti-theft housing must be removed from the ECM to connect the test box. See ENGINE
CONTROL MODULE (ECM) (WITH METAL ANTI-THEFT HOUSING), REPLACING . After
repairs are complete, the metal anti -theft housing must be reinstalled.
z VAG1598/31 test box is designed so that it can be simultaneously connected to the wiring harness at the
Engine Control Module (ECM) and also to the ECM itself.
z This is advantageous because electronic engine control remains fully functional (e.g. measurement of
signals with engine running) when the test box is attached.
z Relevant test procedures note whether Engine Control Module (ECM) should also be connected to the
test box or not.
z Always use VAG1594A connector test kit to attach measurement devices (for example, VAG1527B
voltage tester, VAG1526 multimeter etc.).

Special tools and equipment

z VAG1598/31

Fig. 12: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

VAG1598/31 test box

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WARNING: To reduce the risk of damage to electronic components, switch on power

to components before connecting test leads and observe test
requirements.

z Switch ignition off.

z Remove windshield wiper arms (unscrew).
z Disconnect cover for plenum chamber and place it on windshield side.
z Disengage locking lugs and remove control module connector.
z Connect VAG1598/31 test box to connector of wiring harness. Ground clip (arrow) at test box must be
clipped to battery negative terminal. Relevant test procedures note whether Engine Control Module
(ECM) should also be connected to the test box.

Fig. 13: Connecting VAG1598/31 Test Box To Connector Of Wiring Harness

Courtesy of AUDI OF AMERICA, INC.

z Perform test as described in relevant repair sequence.

Perform the following work after re -connecting Engine Control Module (ECM):

z Check DTC memory and erase it if necessary. See DIAGNOSTIC TROUBLE CODE (DTC)
MEMORY, CHECKING AND ERASING .
z Generate readiness code. See READINESS CODE, GENERATING .

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All models

NOTE: In the first adaptation phase during engine Basic Setting, it is possible that the
idle will be rough and vehicle may shake slightly in drive mode.

Procedure after voltage supply is interrupted

NOTE: In the first adaptation phase during engine Basic Setting, it is possible that the
idle will be rough and vehicle may shake slightly in drive mode.

Special tools and shop equipment

z VAS5051 with VAG5051/1

or

Fig. 14: Identifying Special Tools - VAS5051

Courtesy of AUDI OF AMERICA, INC.

z VAG1551 with VAG1551/3B

Procedure

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Perform the following steps after an interruption in the voltage supply.

z Check DTC memory and erase it if necessary. See DIAGNOSTIC TROUBLE CODE (DTC)
MEMORY, CHECKING AND ERASING .
z Generate readiness code. See READINESS CODE, GENERATING .

Engine Control Module (ECM) (without metal anti-theft housing), replacing

Removing ECMs with metal anti -theft housing. See ENGINE CONTROL MODULE (ECM) (WITH
METAL ANTI-THEFT HOUSING), REPLACING .

NOTE: Adaptation values are erased when connector is disconnected from the Engine
Control Module (ECM), DTC memory content remains intact.

Removing Engine Control Module (ECM)

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

VAG1551 Scan Tool display indicates control module identification (example)

Fig. 15: VAG1551 Scan Tool Display - Control Module Identification

Courtesy of AUDI OF AMERICA, INC.

z First (and always) allow display of control module identification and print it out. See PROCEDURE .
z Compare coding with coding versions. See CODING TABLE .
z Switch ignition off.
z Remove windshield wiper arms (unscrew).
z Disconnect cover for plenum chamber and place it on windshield side.
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z Use a screwdriver to press locking lugs of bracket to the side and then remove Engine Control Module
(ECM) toward front.

Fig. 16: Pressing Locking Lugs Of Bracket To Side Using Screwdriver

Courtesy of AUDI OF AMERICA, INC.

z Disengage locking lugs and remove control module connector.

Installing Engine Control Module (ECM)

Installation is in reverse order of removal, noting the following:

NOTE: In the first adaptation phase during engine Basic Setting, it is possible that idle
will be rough and vehicle may shake slightly in drive mode.

NOTE: Important!

After installing a new Engine Control Module (ECM), the following work steps must be performed:

z Check DTC memory and erase it if necessary. See DIAGNOSTIC TROUBLE CODE (DTC)
MEMORY, CHECKING AND ERASING .
z Observe notes for coding new Engine Control Module (ECM). See CODE CONTROL MODULE .

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z Perform adaptation of throttle valve control module -J338-. See THROTTLE VALVE CONTROL
MODULE, ADAPTATION .
z For vehicles with automatic transmission, position of pedal value sensor for kick down must be learned.
See KICK DOWN FUNCTION, LEARNING .
z Cruise control must be switched off at ECM (if equipped - identify at steering column).

See CRUISE CONTROL SYSTEM (CCS), ON BOARD DIAGNOSIS .

z Generate readiness code. See READINESS CODE, GENERATING .

Engine Control Module (ECM) (with metal anti-theft housing), replacing

Removing ECMs without metal anti -theft housing, see ENGINE CONTROL MODULE (ECM)
(WITHOUT METAL ANTI-THEFT HOUSING), REPLACING .

NOTE: Adaptation values are erased when the harness connector is disconnected from
the Engine Control Module (ECM), the DTC memory content remains intact.

Remove Engine Control Module (ECM)

Removing

z Connect VAS5051 tester and select vehicle system "01 - Engine Electronics". Ignition must be switched
on for this.

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Fig. 17: VAS5051 Scan Tool Display - Engine Electronics

Courtesy of AUDI OF AMERICA, INC.

VAS5051 tester display will indicate the control module identification and coding -2-.

z Always allow display of control module identification first and print it out.
z Switch ignition off.
z Pry off both caps at wiper arms using a screwdriver.
z Loosen hex -nuts (arrows) several turns. See Fig. 18 .
z Loosen wiper arms -1- from wiper axle by lightly tilting. See Fig. 18 .
z Remove hex nuts completely and remove wiper arms.
z Remove plenum chamber cover rubber seal -2-. See Fig. 18 .
z Remove plenum chamber cover -3- and place it on windshield side.

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Fig. 18: Removing Plenum Chamber Cover

Courtesy of AUDI OF AMERICA, INC.

NOTE: Item -1- in illustration shows the Engine Control Module (ECM) with anti-theft
housing.

z Use a screwdriver to press locking lug of bracket (arrow) to the side and then remove Engine Control
Module (ECM) toward front.

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Fig. 19: Removing Engine Control Module (ECM)

Courtesy of AUDI OF AMERICA, INC.

To restrict accessibility (for theft prevention) to the harness connectors and Engine Control Module (ECM), the
Engine Control Module (ECM) -1- is screwed to a metal anti-theft housing -4- via a locking mechanism -2- and
snap-off screws -3-.

The threads of the snap -off screws are coated with locking compound to make it more difficult to remove the
snap -off screws.

To disconnect the harness connectors from the Engine Control Module (ECM) (for example, when connecting a
test box or when replacing the ECM), the ECM must be removed from the metal anti-theft housing. This
procedure is described as follows.

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Fig. 20: Engine Control Module With Metal Anti-Theft Housing

Courtesy of AUDI OF AMERICA, INC.

The following equipment is required:

z Heat gun -1- (from VAS1978 Wiring Harness Repair Kit)

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Fig. 21: Identifying Heat Gun And Adapter Nozzle

Courtesy of AUDI OF AMERICA, INC.

z Adapter nozzle -2- (also from VAS1978 Wiring Harness Repair Kit)
z Standard locking pliers

Procedure:

WARNING: The following work steps must be adhered to exactly to avoid damage
(burning) of wires, harness connectors, insulation and control modules!
Observe operating instructions of heat gun.

z "Flip" the Engine Control Module (ECM) with anti -theft housing in direction of the engine compartment
so that the locking mechanism (item -2- in illustration) becomes visible and place a clean rag below the
Engine Control Module (ECM) with anti -theft housing.

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Fig. 22: Identifying ECM Components (With Metal Anti-Theft Housing)

Courtesy of AUDI OF AMERICA, INC.

z Adjust the heat gun as shown in illustration, i.e. temperature adjustment -2- to maximum heat output and
the two -stage switch for air mass -3- to position 3.

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Fig. 23: Adjusting Heat Gun

Courtesy of AUDI OF AMERICA, INC.

NOTE: Next, use the heat gun to heat the threads of the locking mechanism in which
the snap -off screws are screwed into. This step loosens the locking compound
on the threads of the snap-off screws for easier removal.

WARNING: By heating the locking mechanism threads, the snap - off screws and
parts of the metal anti -theft housing will also become very hot. Be careful
not get burned! If possible, also make sure that only the threads are no
parts in the vicinity become heated. If necessary, cover them.

z Guide nozzle -1- of heat gun to the locking mechanism threads so that the nozzle "encloses" the threads.
It is OK to let the nozzle make contact at the upper end of the metal anti -theft housing.

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Fig. 24: Guiding Nozzle Of Heat Gun To The Locking Mechanism Threads
Courtesy of AUDI OF AMERICA, INC.

z Switch on heat gun and heat up thread for approx. 20 to 25 seconds.

z Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of
arrow.

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Fig. 25: Removing Snap-Off Screw Using Locking Pliers

Courtesy of AUDI OF AMERICA, INC.

The procedure for the second snap-off screw is exactly the same. Be very careful since the control module
connector is in close proximity.

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Fig. 26: Guiding Nozzle Of Heat Gun To The Locking Mechanism Threads
Courtesy of AUDI OF AMERICA, INC.

z Guide nozzle -1- of the heat gun to the locking mechanism threads again so that the nozzle "encloses" the
threads. It is OK to let the nozzle make contact at the upper end of the metal anti -theft housing.
z Switch on heat gun and heat up threads for approx. 20 to 25 seconds.

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Fig. 27: Removing Snap-Off Screw Using Locking Pliers

Courtesy of AUDI OF AMERICA, INC.

z Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of
arrow.

The Engine Control Module (ECM) can now be removed from the metal anti-theft housing.

z Disengage connectors from Engine Control Module (ECM) and then disconnect connectors.
z Remove old Engine Control Module (ECM) and insert new one.

Installing Engine Control Module (ECM)

Installation is the reverse order of removal, noting the following:

After repairs are complete, the metal anti -theft housing must be reinstalled. Use new snap-off screws.
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z Bend back locking lug of bracket.

After installing a new Engine Control Module (ECM), the following work steps must be performed:

z Activate Engine Control Module (ECM) in "Guided Troubleshooting" below subject heading "Engine
Control Module (ECM), replacing".

Use VAS5051 tester to do so.

Idle speed, checking

Special tools and equipment

z VAS5051 with VAG5051/1

or

z VAG1551 with VAG1551/3B

Fig. 28: Identifying Special Tool VAS5051

Courtesy of AUDI OF AMERICA, INC.

Test conditions

z Exhaust system free of leaks

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z Engine coolant temperature less than 80 °C

z Electrical consumers switched off (radiator fan must NOT run during test)
z A/C switched off
z Pressure gauge not connected
z Vehicles with automatic transmission: selector lever in P or N

NOTE: z Idle speed cannot be adjusted.

z Idle speed is checked during Basic Setting of the engine.
z During Basic Setting, the Evaporative Emission (EVAP) canister purge
regulator valve (EVAP valve -N80-) is closed and the A/C compressor is
switched off.

Test sequence

z Check DTC memory. See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND
ERASING . There must not be any DTCs stored, repair malfunctions if necessary, erase DTC memory,
switch engine off and start again, road test vehicle and check DTC memory again as a control measure.
z Let engine continue to run at idle.

WARNING: Engine coolant fan must not come on during test.

When indicated on display:

Fig. 29: VAG 1551 Scan Tool Display - Idle Speed, Checking (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -4- to select "Basic Setting" and press -Q- button to confirm input.

When indicated on display:

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Fig. 30: VAG 1551 Scan Tool Display - Idle Speed, Checking (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -5- and -6- to select "display group number 056" and press -Q- button to confirm input.

Indicated on display:

Fig. 31: VAG 1551 Scan Tool Display - Idle Speed, Checking (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Check whether engine speed in display field 1 (actual engine speed) is within permitted tolerance range.

DISPLAY GROUP 56: IDLE STABILIZATION WITH ENGINE AT IDLE AND OPERATING
TEMPERATURE
Display fields
1 2 3 4
Display group 56: Idle stabilization with engine at idle and operating temperature
Display xxx /min xxx /min x.x % XXXXX
Indicated Engine speed (actual) Engine speed Idle control Operating conditions
(specified) torque change
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Specified 800 - 920 RPM(1) 860 RPM (1) x.x % 00000

value: 720 - 840 RPM (2) 780 RPM (2)

640 - 760 RPM (3) 700 RPM (3)

Note: If specified value is not Significance of numbers,
obtained, see TEST see TEST SEQUENCE
SEQUENCE
(1) Vehicles with Front Wheel Drive (FWD) and manual transmission

(2) Vehicles with All Wheel Drive (AWD) and manual transmission
(3) Vehicles with Front Wheel Drive (FWD) and automatic transmission

NOTE: z Engine speed in display field 1 (actual engine speed) is the current engine
speed.
z Engine speed in display field 2 (specified engine speed) is a theoretical
engine speed calculated by the ECM.
z At idle, the ECM always attempts to adapt the engine speed (actual) to the
specified engine speed (specified).
z This means that the engine speed (actual) must always approximately
match the engine speed (specified) at idle.
z Display fields 3 and 4 provide information, but are not relevant for
checking idle speed.

If specified value is obtained:

z Press -->button.

Indicated on display (function selection):

Fig. 32: VAG 1551 Scan Tool Display - Idle Speed, Checking (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

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If specified value is not obtained:

z Check DTC memory again. See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING
AND ERASING .
z If DTC memory was erased, readiness code must be re-generated. See READINESS CODE,
GENERATING .

If idle speed is too high or low and there are no DTCs in DTC memory, the following tests (marked with
diamonds) must be performed

z Un-metered air in intake air system, checking. See INTAKE AIR SYSTEM, CHECKING FOR
LEAKS (UN-METERED AIR) .
z Check throttle valve control module. See THROTTLE VALVE CONTROL MODULE -J338-,
CHECKING .
z Evaporative Emission (EVAP) canister purge regulator valve always open, checking. See TANK
VENTILATION, CHECKING .
z Perform adaptation of throttle valve control module. See THROTTLE VALVE CONTROL
MODULE, ADAPTATION .

Significance of 5 digit display of display group 056

SIGNIFICANCE OF 5 DIGIT DISPLAY OF DISPLAY GROUP 056

x x x x x Display field 4
0 A/C compressor
0 = A/C compressor off
1 = A/C compressor on
0 Driving mode selected
0 = selector lever in P or N
1 = selector lever in 2/3/4/D/R
0 A/C readiness maximum heating/cooling power
0 Indication always 0
0 Power steering pressure
0 = no signal from pressure switch for power steering
1 = signal from pressure switch for power steering (steering fully turned to stop)

System pressure, fuel pressure regulator and residual pressure, checking

Special tools and equipment

z VAG1318

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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

Fig. 33: Identifying Special Tool VAG1318

Courtesy of AUDI OF AMERICA, INC.

z VAG1318/7
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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

z VAG1318/17 (2x)

Fig. 34: Identifying Special Tool VAG1318/17

Courtesy of AUDI OF AMERICA, INC.

NOTE: Fuel pressure regulator regulates fuel pressure according to intake manifold
pressure. This ensures that the pressure drop at the fuel injectors remains the
same for each speed and load range of the engine.

Test conditions

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z Fuel Pump (FP) OK, checking. See FUEL PUMP (FP) RELAY -J17-, CHECKING ACTIVATION .
z Fuel Pump (FP) OK, checking:

See FUEL PUMP, ELECTRICAL TESTING .

z Fuel filter OK
z Battery voltage at least 11 V

WARNING: The fuel system is under pressure. When opening the system, place a rag
around connections then release pressure by carefully prying open
connection

Checking system pressure

z Open fuel filler flap briefly (release pressure).

z Remove fuel supply hose -1- (with white marking) from supply line.

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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

Fig. 35: Removing Fuel Supply Hose From Supply Line

Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1318 using adapters 1318/7 and 1318/17 (2 pieces) at supply line.

Fig. 36: Connecting VAG1318 At Supply Line

Courtesy of AUDI OF AMERICA, INC.

z Open valve of pressure gauge. Lever points in direction of flow.

z Start engine and let run at idle.
z Measure fuel pressure.
z Specified value: approx. 2.5 bar positive pressure

z Disconnect vacuum hose at fuel pressure regulator.

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Fig. 37: Disconnecting Vacuum Hose At Fuel Pressure Regulator

Courtesy of AUDI OF AMERICA, INC.

z Fuel pressure must rise to approx. 3.0 bar positive pressure.

z Switch ignition off.
z Check for proper seal and residual pressure by observing pressure drop on pressure gauge.
z After 10 minutes, there must be at least 1.5 bar positive pressure

If residual pressure sinks below 1.5 bar positive pressure:

z Start engine and let run at idle.

z Switch ignition off after pressure has built up. Simultaneously close valve of VAG1318 pressure gauge
(lever perpendicular to direction of flow -arrow-).

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Fig. 38: Closing Valve Of VAG1318 Pressure Gauge (Lever Perpendicular To Direction Of Flow)
Courtesy of AUDI OF AMERICA, INC.

z Observe pressure drop on pressure gauge.

If pressure does not drop now:

z Check check-valve of Fuel Pump (FP).

If pressure drops again:

z Open valve of VAG1318 pressure gauge (lever in direction of flow).

z Start engine and let run at idle.
z Switch ignition off after pressure has built up. Simultaneously clamp return line (with blue marking) fully
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closed (sealed).

If pressure does not drop now:

z Replace fuel pressure regulator

If pressure drops again:

z Check wire connections, O -rings at fuel distributor and fuel injectors for proper seal.
z Check pressure gauge for proper seal.

NOTE: Before disconnecting pressure gauge, release pressure by opening valve. Hold
a container in front of connection for this.

Fuel injectors, checking

Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31

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Fig. 39: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Checking internal resistance

z Disconnect connector at the injector to be tested.

z Connect multimeter at valve for resistance measurement.

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Fig. 40: Checking Fuel Injector Resistance

Courtesy of AUDI OF AMERICA, INC.

z Specified value: 12 - 13 ohm(at room temperature)

If specified value is not obtained:

z Replace fuel injector. See FUEL INJECTORS, REMOVING AND INSTALLING .

If specified value is obtained:

Checking voltage supply

Test conditions

z Fuel Pump (FP) OK. Checking, see FUEL PUMP (FP) RELAY -J17-, CHECKING ACTIVATION .
z Fuse for fuel injectors OK.

See appropriate System Wiring Diagrams article.

z Disconnect connector at the injector to be tested.

z Connect VAG1527B voltage tester as follows:

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Fig. 41: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

FUEL INJECTOR CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector terminal Measure to
1 Engine Ground

z Operate starter briefly (engine can also start).

z LED must light.

If LED does not light:

z Check wire connection between terminals 1 and fuse for injector valves for open circuit.

See appropriate System Wiring Diagrams article.

z Repair open circuit if necessary.

If LED lights, go to CHECKING ACTIVATION .

Checking activation

Test requirement

z Internal resistance of injector OK:

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z Slide back rubber grommet of fuel injector connector, but leave connector connected.
z Connect VAG1527B voltage tester between sockets 2 (signal) and 1 (B+).

Fig. 42: Connecting VAG1527B Voltage Tester Between Fuel Injector Sockets
Courtesy of AUDI OF AMERICA, INC.

z Operate starter briefly (engine can also start).

z LED must blink.

NOTE: Voltage testers do not go out completely between activations by the ECM, but
rather continue to glow and then get slightly brighter during activation.

If LED does not blink:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

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Fig. 43: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground and B+:

FUEL INJECTOR CIRCUIT TEST - OPENS/SHORTS

Cylinder Fuel injector harness connector terminal VAG1598/31 test box socket
1 2 96
2 2 89
3 2 97
4 2 88

z Repair open circuit or short circuit if necessary.

If wire connection is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Fuel distributor with fuel injectors, disassembling and assembling

The following list pertains to Fig. 44 .

1. - Fuel injector insert - 3 Nm

z Use locking fluid D 000 600 A2 when installing

2. - O-Ring
z Always replace

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3. - Fuel injectors -N30 through N33-

4. - Supply hose
5. - Return hose
6. - Fuel distributor
7. - Socket-head bolt - 10Nm
8. - Harness connector
z For injectors

z pieces

9. - Fuel pressure regulator

10. - O-Ring
z Always replace

11. - O-Ring
z Always replace

12. - Retaining clip

13. - O-Ring
z Always replace

14. - Retaining clip

z Check for proper seating at fuel injector and fuel distributor

15. - Intake manifold

Fig. 44: Exploded View Of Intake Manifold And Fuel Rail

Courtesy of AUDI OF AMERICA, INC.

Fuel injectors, removing and installing

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z Disconnect wiring/connectors at:

z Fuel injectors -N30-, -N31-, -N32-, -N33-

z Intake Air Temperature (IAT) sensor - G42-

z Camshaft Position (CMP) sensor 2 -G163 -

z Throttle valve control module -J338-

z Charge air pressure sensor -G31-

z Detach cable channel to fuel injectors.

z Remove 2 socket -head bolts for fuel distributor.
z Disconnect fuel supply and return lines at quick - release connection in front of right suspension strut.
z Disconnect vacuum hose from fuel pressure regulator.
z Place fuel distributor toward front.

WARNING: The fuel system is under pressure. When opening the system, place a rag
around connections then release pressure by carefully prying open
connection.

z Disengage retaining clip and remove fuel injector.

NOTE: Fuel lines must be disconnected before replacing fuel distributor.

Installation is in reverse order of removal, noting the following:

z O-rings at all opened connections. (Never remove plastic cap from valve head or replace front O -ring,
pry O-ring off over plastic cap).
z Lightly lubricate O-rings with clean engine oil.
z Make sure fuel injectors are in place and seated correctly.
z Check clip for unobstructed fitting.
z Place fuel distributor, with fuel injectors securely installed, on intake manifold and press in evenly.

Tightening torque

Fuel distributor at intake manifold: 10 Nm.

Injection quantity, proper seal and spray pattern of fuel injectors, checking

Special tools and equipment

z VAG1348/3-2
z VAG1348/3A
z VAG1594A
z VAG1602

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z VAS5051 with VAG5051/1

or

z VAG1551 with VAG1551/3B

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Fig. 45: Identifying Special Tools And Equipment

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Courtesy of AUDI OF AMERICA, INC.

Test requirement

z Fuel pressure OK, checking. See SYSTEM PRESSURE, FUEL PRESSURE REGULATOR AND
RESIDUAL PRESSURE, CHECKING .

Test sequence

z Remove fuel distributor including fuel injectors from intake manifold. See FUEL INJECTORS,
REMOVING AND INSTALLING . Fuel lines remain connected.
z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
z Bridge terminals 1 and 65 at test box using adapter cables from VAG1594A connector test kit (this step
supplies Ground to one side of relay coil of Fuel Pump -FP- relay).

Checking for proper seal

z Turn ignition on.

NOTE: After switching ignition on, Fuel Pump (FP) will run continuously, even with
engine not running. This is true because: Fuel Pump (FP) relay is supplied with
B+ via central electrics after ignition is switched on. Fuel Pump (FP) relay
Ground connection is via the cable bridge in test box.

z Check to make sure fuel injectors are not leaking (visual check). With Fuel Pump (FP) running, only 1 - 2
drops per minute may drip out per injector.
z If fuel loss is greater, stop Fuel Pump (FP) from running (End Output DTM) and replace malfunctioning
fuel injector. See FUEL INJECTORS, REMOVING AND INSTALLING .

Checking injection quantity

z Insert fuel injector to be tested in a measuring glass from VAG1602 injection quantity test device.
z Connect one terminal of fuel injector to engine Ground using an adapter cable and an alligator clip from
VAG1594A connector test kit.
z Connect the second terminal of fuel injector to B+ using VAG1348/3A remote control, VAG1348/3 -2
adapter cable and assisting cable.

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Fig. 46: Connecting VAG1348/3A Remote Control To Fuel Injector

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

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z Fuel Pump (FP) must run

z Activate VAG1348/3A remote control for 30 seconds.
z Perform measurement on all fuel injectors.
z After all four fuel injectors have been activated, place measuring glasses on an even surface.
z Specified value for each fuel injector: 145 = 12 ml

z If measured value of one or more fuel injectors is outside of specified range, switch Fuel Pump (FP) off
(switch ignition off) and replace malfunctioning fuel injector. See FUEL INJECTORS, REMOVING
AND INSTALLING .

NOTE: Also check spray pattern when checking injection quantity. Spray pattern must
be the same for all injectors.

z Remove fuel injectors together with fuel distributor. See FUEL INJECTORS, REMOVING AND
INSTALLING .

Fuel Pump (FP) relay -J17-, checking activation

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31

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Fig. 47: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Test requirement

Voltage is supplied to the Fuel Pump (FP) and several components of the injection system via the Fuel Pump
(FP) relay -J17-.

For Fuel Pump (FP) relay -J17- to close, it is required that engine is turning. This means that the relay does not
receive Ground (via ECM) until the ECM recognizes RPM signals.

NOTE: Fuel Pump (FP) relay is located at position 4 of micro-central electrics in

driver's footwell, left.

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Fig. 48: Locating Fuel Pump (FP) Relay (Position 4)

Courtesy of AUDI OF AMERICA, INC.

z Battery voltage at least 11 V

Function test of Fuel Pump (FP) relay

z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

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z Initiate Output Diagnostic Test Mode (see OUTPUT DIAGNOSTIC TEST MODE (DTM) ) and
activate Evaporative Emission (EVAP) canister purge regulator valve -N80-.
z Fuel Pump (FP) relay (at position 4 of micro -central electrics in driver's footwell, left) must trigger
and Fuel Pump (FP) must run.

Fig. 49: Locating Fuel Pump (FP) Relay (Position 4)

Courtesy of AUDI OF AMERICA, INC.

If relay does not trigger:

z Check activation of Fuel Pump (FP) relay.

If Fuel Pump (FP) does not run:

z Check voltage supply for fuel pump (FP) and components (via Fuel Pump -FP- relay). See CHECK
VOLTAGE SUPPLY FOR FUEL PUMP (FP) AND COMPONENTS .

Check activation of Fuel Pump (FP) relay

z Switch ignition off.

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z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
z Connect socket 65 and socket 2 of test box to each other using wire from VAG1594 connector test kit.
z Switch ignition on.

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Fig. 50: Locating Fuel Pump (FP) Relay (Position 4)

Courtesy of AUDI OF AMERICA, INC.

z Fuel Pump (FP) relay (at position 4 of micro -central electrics in driver's footwell, left) must
trigger.

If relay triggers now, but didn't during output DTM:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

If relay does not trigger:

z Switch ignition off.

z Remove Fuel Pump (FP) relay.
z Connect multimeter to terminal 19 of relay socket and Ground for voltage measurement.

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Fig. 51: Identifying Fuel Pump Relay Sockets In Relay Carrier

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Specification: approx. battery voltage

If specified value is not obtained:

z Check wire connections.

See appropriate System Wiring Diagrams .

If specified value is obtained:

z Switch ignition off.

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Fig. 52: Identifying Fuel Pump Relay Sockets In Relay Carrier

Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connection for open circuit and short circuit to Ground and B+:

FUEL PUMP RELAYCIRCUIT TEST - OPENS/SHORTS

Micro-central electronics in drivers - side footwell, left, position 4 VAG1598/31 test box
terminal socket
16 65

z Repair open circuit or short circuit if necessary.

z If wire connections are OK, replace Fuel Pump (FP) relay -J17-.

Check voltage supply for Fuel Pump (FP) and components

z Remove fuse Nos. S28, S32, S34 and S43 from fuse holder.
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Fig. 53: Identifying Fuse Holder

Courtesy of AUDI OF AMERICA, INC.

z Initiate Output Diagnostic Test Mode (see OUTPUT DIAGNOSTIC TEST MODE (DTM) ) and
activate Evaporative Emission (EVAP) canister purge regulator valve -N80-.
z Connect multimeter to Ground and to one terminal of the following fuses in fuse holder for voltage
measurement.

FUSES FOR VOLTAGE SUPPLY TO FUEL PUMP

Locking clip Specified value at one of the terminals
S28 approx. battery voltage
S32 approx. battery voltage
S34 approx. battery voltage

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S43 approx. battery voltage

If specified values are not obtained:

z Repeat test at another terminal of fuse socket.

If specified values are not obtained again:

z Check wire connections.

See appropriate System Wiring Diagrams article.

z If wire connections are OK, replace Fuel Pump (FP) relay -J17-.

Mass Air Flow (MAF) sensor - G70-, checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1
{ or

z VAG1551 with VAG1551/3B

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Fig. 54: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Test conditions

z Coolant Temperature less than 80 °C

z Electrical consumers switched off (radiator fan must NOT run during test)
z A/C switched off
z Fuse for Mass Air Flow (MAF) sensor OK

See appropriate System Wiring Diagrams article.

Checking function

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION

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SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

When indicated on display:

Fig. 55: VAG 1551 Scan Tool Display - MAF Sensor, Checking (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -4- to select "Basic Setting" and press -Q- button to confirm input.

NOTE: During Basic Setting, the Evaporative Emission (EVAP) canister purge regulator
valve (EVAP valve -N80-) is closed and the A/C compressor is switched off

When indicated on display:

Fig. 56: VAG 1551 Scan Tool Display - MAF Sensor, Checking (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

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z Press buttons -0-, -0- and -2- to select "display group number 002" and press -Q- button to confirm input.

Indicated on display:

Fig. 57: VAG 1551 Scan Tool Display - MAF Sensor, Checking (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Check specified values for load detection.

DISPLAY GROUP 2: AIR MASS TAKEN IN WITH ENGINE AT IDLE AND OPERATING
TEMPERATURE
Display fields
1 2 3 4
Display group 2: Air mass taken in with engine at idle and operating temperature
Display xxx /min xx.x x.x ms xxx.x g/s
%
Indicated Engine Load mean injection time Air mass
speed
(RPM)
(in
increments
of 40)
Work min.: 800 min.: min.: 2.0 ms min.: 2.0 g/s
area RPM 15 % max.: 19.0 ms max.: 170.0 g/s
max.: 6800 max.:
RPM 175 %
Specified 800 - 920 15.0 - 2.0 - 4.0 ms 2.0 - 4.5 g/s
value: RPM 25.0
%
Note: --- --- If specified value is not obtained: If specified value is not obtained:
Evaluation display field 3, see Evaluation display field 4, see
DISPLAY FIELDS DISPLAY FIELDS
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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

SPECIFICATION SPECIFICATION

If specified value is obtained:

z Press -->button.

Indicated on display (function selection):

Fig. 58: VAG 1551 Scan Tool Display - MAF Sensor, Checking (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

Evaluation display group 002

EVALUATION DISPLAY GROUP 002 (1 OF 2)

Display
field: 3 Possible cause Corrective action
less than z Smaller values can only occur
2.0 ms when driving in deceleration
mode
larger than z Engine under load due to z Reduce load (A/C system/power
4.0 ms power accessories steering/generator)
z Poor idle (does not run on all z Check spark plugs
cylinders) z Check fuel injectors, see FUEL INJECTORS,
CHECKING
z Throttle valve control module z Check throttle valve control module. See
-J338- malfunctioning THROTTLE VALVE CONTROL MODULE
-J338-, CHECKING .

EVALUATION DISPLAY GROUP 002 (2 OF 2)

Display
field: 4 Possible cause Corrective action
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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

Smaller z Large un-metered air mass zCheck intake system for leaks (unmetered air).
than 2.0 between intake manifold and See INTAKE AIR SYSTEM, CHECKING
g/s Mass Air Flow (MAF) sensor FOR LEAKS (UN-METERED AIR)
z Voltage supply of Mass Air z Check voltage supply and wire connections. See
Flow (MAF) sensor and wire CHECK VOLTAGE SUPPLY FOR MASS
connections to engine AIR FLOW (MAF) SENSOR .
Larger z Engine under load due to z Reduce load (A/C system/power
than 4.5 power accessories. steering/generator)
g/s
z Voltage supply of Mass Air z Check voltage supply and wire connections. See
Flow (MAF) sensor and wire CHECK VOLTAGE SUPPLY FOR MASS
connections to engine AIR FLOW (MAF) SENSOR .

Check voltage supply for Mass Air Flow (MAF) sensor

z Disconnect connector at Mass Air Flow (MAF) sensor.

z Connect multimeter for voltage measurement as follows.

Fig. 59: Identifying Mass Air Flow Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

MAF SENSOR CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector terminal Measure to
2 Engine Ground

z Operate starter briefly.

z Specification: approx. battery voltage

NOTE: Voltage is supplied to Mass Air Flow (MAF) sensor via Fuel Pump (FP) relay.

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If specified value is not obtained:

z Check wire connection from terminal 2 of connector to Fuel Pump (FP) relay via fuse for open circuit and
short circuit to Ground:

See appropriate System Wiring Diagrams article.

z Repair open circuit or short circuit if necessary.

Fig. 60: Identifying Mass Air Flow Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter to terminal 2 and terminal 3 of connector for voltage measurement.

z Operate starter briefly.
z Specification: approx. battery voltage

NOTE: Ground from the ECM is present at terminal 3 of connector.

If specified value is not obtained:

z Check wire connections. See CHECK WIRE CONNECTIONS FOR MASS AIR FLOW (MF)
SENSOR .

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Fig. 61: Identifying Mass Air Flow Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter to terminal 3 and terminal 4 of connector for voltage measurement.

z Switch ignition on.
z Specification: approx. 5 V

If specified value is not obtained:

z Check wire connections. See CHECK WIRE CONNECTIONS FOR MASS AIR FLOW (MF)
SENSOR .

Check wire connections for Mass Air Flow (MF) sensor

NOTE: Signal wire is also checked during wire test.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

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Fig. 62: Identifying Mass Air Flow Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground and B+:

MAF SENSOR CIRCUIT TEST - OPENS/SHORTS

Harness connector terminal VAG1598/31 test box socket
3 27
4 53
5 29

z Repair open circuit or short circuit if necessary.

z Also check all wires for short circuit to each other.

If wire connection is OK:

z Replace Mass Air Flow (MAF) sensor -G70-.

Intake air system, checking for leaks (un-metered air)

Special tools and equipment

z VAS5051 with VAG5051/1

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Fig. 63: Identifying Special Tool VAS5051

Courtesy of AUDI OF AMERICA, INC.

or

z VAG1551 with VAG1551/3B

z Engine leak detection spray G 001 800 A1

NOTE: z Leak detection spray is drawn into intake system along with un-metered
air by vacuum in intake system. Leak detection spray decreases ignition
quality and performance of the fuel mixture. This causes a reduction in
engine speed and a sharp increase of CO content.
z Always observe the safety precautions printed on can.

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

When indicated on display:

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Fig. 64: VAG 1551 Scan Tool Display - Intake Air System, Checking For Leaks (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 65: VAG 1551 Scan Tool Display - Intake Air System, Checking For Leaks (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -0- and -1- to select "display group number 001" and press -Q- button to confirm input.

Indicated on display: (1 - 4 = display fields)

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Fig. 66: VAG 1551 Scan Tool Display - Intake Air System, Checking For Leaks (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Note engine speed in display field 1.

z Systematically spray parts of intake system with engine leak detection spray.

If engine speed does not change:

z Press -->button.

Indicated on display (function selection):

Fig. 67: VAG 1551 Scan Tool Display - Intake Air System, Checking For Leaks (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

If engine speed decreases:

z Press -->button.
z Press buttons -0- and -6- to select "End output" and press -Q- button to confirm input.
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z Switch ignition off.

z Check sprayed portions of intake system for leaks and repair malfunction.

OXYGEN SENSOR CONTROL, CHECKING

Function of oxygen sensor control before catalytic converter

NOTE: z Oxygen sensor compares oxygen content of air with residual oxygen
content in exhaust and delivers a voltage signal to the control module.
z The voltage signal "mixture rich (too little residual oxygen)" is 0.7 - 1.1 V
(relative to reference Ground).
z The voltage signal "mixture lean (too much residual oxygen)" is -0.1 to
+0.3 V (relative to reference Ground).
z During transition from "rich" to "lean" and vice versa ("lambda" = 1.0) the
voltage jumps from range of 0.7 to 1.1 V to range of -0.1 to +0.3 V or vice
versa.
z Due to the steep voltage jump, oxygen sensor control cannot maintain the
ideal mixture of "lambda" = 1.0 as constant. Oxygen sensor control
constantly fluctuates back and forth between the conditions "slightly too
lean" and "slightly too rich."

NOTE: If voltage change does not occur or occurs only slowly, the following
malfunctions could be present:

z Slits or holes in sensor head clogged.

z Sensors suffered thermal overload.
z Transition resistance in signal wire or Ground wire.
z Sensor too cold, sensor heating not functioning.
z Sensor damaged by contact spray or similar substance (contact spray is
drawn through the fine hollow interiors by thermal fluctuations and
capillary action into the electrical wiring in sensor).
z Sensor damaged by silicon fumes (The use of sealing materials containing
silicon leads to traces of silicon to be drawn in by the engine. These traces
are not combusted and damage the oxygen sensors).

Oxygen sensor and oxygen sensor control before catalytic converter, checking

Special tools and shop equipment

z VAG1526A
z VAG1594A
z VAG1598/31

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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection (MFI), 1.8L Turbo, ATC - TT

z VAS5051 with VAG5051/1

{ or

z VAG1551 with VAG1551/3B

Fig. 68: Identifying Special Tools And Shop Equipment

Courtesy of AUDI OF AMERICA, INC.

Test conditions

z For the defined troubleshooting procedure, it is possible, to switch oxygen sensor control off by selecting
display group 99 under "Basic Setting" and switch it on again under "Read Measuring Value Block."
z After selecting display group 99 (either in "Basic Setting" or "Read Measuring Value Block"), it is
possible to switch back and forth between "Basic Setting" (function 04) and "Read Measuring Value
Block" (function 08) by pressing buttons 4 or 8 on the VAG1551.
z Once function 04 "Basic Setting" is exited, oxygen sensor control is automatically switched on again.
z The 4-pin harness connectors for the oxygen sensor before catalytic converter (black) and for the oxygen
sensor behind catalytic converter (brown) are located under a cover -2- at vehicle floor.

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Fig. 69: Locating Oxygen Sensors And Cover

Courtesy of AUDI OF AMERICA, INC.

z Road test performed and DTC memory erased

z Coolant Temperature less than 80 °C

Function test

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

When indicated on display:

Fig. 70: VAG 1551 Scan Tool Display - HO2S And HO2S Control Before Catalytic Converter, Function
Test (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

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z Press buttons -0- and -4- to select "Basic Setting" and press -Q- button to confirm input.

NOTE: During Basic Setting, the Evaporative Emission (EVAP) canister purge regulator
valve (EVAP valve -N80-) is closed and the A/C compressor is switched off

When indicated on display:

Fig. 71: VAG 1551 Scan Tool Display - HO2S And HO2S Control Before Catalytic Converter, Function
Test (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -3- and -0- to select "display group number 030" and press -Q- button to confirm input.

When indicated on display:

Fig. 72: VAG 1551 Scan Tool Display - HO2S And HO2S Control Before Catalytic Converter, Function
Test (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

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z Check oxygen sensor status in display field 1.

NOTE: "Oxygen sensor status" indicates status of oxygen sensor control and oxygen
sensor.

DISPLAY GROUP 30: OXYGEN SENSOR STATUS

Display fields
1 2 3 4
Display group 30: Oxygen sensor status
Display XXX XXX
Indicated Oxygen sensor status, bank 1, sensor 1 Oxygen sensor status, bank 2, sensor 1
Work area 0 = off 0 = off
1 = on 1 = on
Specified 111 110
value:
Note: If specified value is not obtained, see CHECKING PRIMARY VOLTAGE
If specified value is obtained but there is a malfunction stored in DTC memory, see
CHECKING OXYGEN SENSOR ADAPTATION VALUES AND CONTROL

Significance of 3 digit indication of display group 030

SIGNIFICANCE OF 3 DIGIT INDICATION OF DISPLAY GROUP 030

X X X Display field 1
1 Oxygen sensor control active
1 Operational readiness of oxygen sensor
1 Condition of oxygen sensor heating

NOTE: The first field of the 3 digit indication (heating) fluctuates between 0 and 1.

Checking oxygen sensor adaptation values and control

z Press -C- button.

z Press buttons -0-, -3- and -2- to select "display group number 032" and press -Q- button to confirm input.

When indicated on display:

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Fig. 73: VAG 1551 Scan Tool Display - Checking HO2S Adaption Values And Control (1 Of 2)
Courtesy of AUDI OF AMERICA, INC.

z Check oxygen sensor control in display fields 1 and 2.

DISPLAY GROUP 32: OXYGEN SENSOR ADAPTATION VALUES

Display fields
1 2 3 4
Display group 32: Oxygen sensor adaptation values
Display xx.x % xx.x %
Indicated Oxygen sensor adaptation value Oxygen sensor adaptation value bank 1,
bank 1, sensor 1 at idle (additive) sensor 1 at partial throttle (multiple)
Work area -25.0 to 25.0 % -25.0 to 25.0 %
Specified -10.0 to 10.0 % -10.0 to 10.0 %
value: can fluctuate slightly can fluctuate slightly
Note: If specified value is not obtained, see CHECKING PRIMARY VOLTAGE .

z Press -C- button.

z Press buttons -0-, -3- and -3- to select "display group number 033" and press -Q- button to confirm input.

When indicated on display:

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Fig. 74: VAG 1551 Scan Tool Display - Checking HO2S Adaption Values And Control (2 Of 2)
Courtesy of AUDI OF AMERICA, INC.

z Check oxygen sensor control in display fields 1 and 2.

DISPLAY GROUP 33: OXYGEN SENSOR CONTROL

Display fields
1 2 3 4
Display group 33: Oxygen sensor control
Display xx.x % x.xxx V
Indicated Oxygen sensor control Bank Oxygen sensor voltage bank 1
1
Work area -25.0 to 25.0 % 0.000 - 1.000 V
Specified Value must fluctuate at least Value must fluctuate approx. 0.3 V in the range
value: 2 % in the range -10.0 to 0.000 - 1.000 volts
10.0 %
Note: If specified value is not If specified value is not obtained, see Evaluation
obtained, continue with test. display group 033. See DISPLAY FIELDS
SPECIFICATION

If specified value in display field 1 is not obtained or if value does not fluctuate at least 2 %:

z Road test vehicle in order to free oxygen sensor of possible residue and repeat test.

If specified value in display field 1 is not obtained even after road test or if value does not fluctuate at least 2 %:

z See CHECKING PRIMARY VOLTAGE .

z Check oxygen sensor heating. See OXYGEN SENSOR HEATING FOR OXYGEN SENSORS
BEFORE AND AFTER CATALYTIC CONVERTER, CHECKING .
z Check oxygen sensor before catalytic converter for aging. See OXYGEN SENSOR AGING, OXYGEN
SENSOR BEFORE CATALYTIC CONVERTER, CHECKING .
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Evaluation display group 32

EVALUATION OF DISPLAY GROUP 32 (1 OF 2)

Display field: 1 / 2 Possible cause Corrective action
Oxygen sensor z Leak in intake area (pressure z Check intake system for leaks
adaptation values in side between turbocharger and and repair un-metered air, see
range: -10.0 to - 25.0 % intake manifold) INTAKE AIR SYSTEM,
CHECKING FOR LEAKS
(UN-METERED AIR)
z Oil thinning z Change oil or perform swift
road test on a deserted road
z High oil consumption
z Mass Air Flow (MAF) sensor z Check Mass Air Flow (MAF)
malfunctioning sensor, see MASS AIR FLOW
(MAF) SENSOR - G70-,
CHECKING
z Evaporative Emission (EVAP) z Check Evaporative Emission
canister purge regulator valve (EVAP) Canister Purge
remains stuck in open position Regulator Valve, see TANK
VENTILATION,
CHECKING
z Fuel pressure too high z Check fuel pressure
regulator, see SYSTEM
PRESSURE, FUEL
PRESSURE REGULATOR
AND RESIDUAL
PRESSURE, CHECKING
z Fuel injector does z Check fuel injectors, see FUEL
not close INJECTORS, CHECKING
z Oxygen sensor z Check oxygen sensor heating,
heating see OXYGEN SENSOR
malfunctioning HEATING FOR OXYGEN
z Oxygen sensor SENSORS BEFORE AND
malfunctioning AFTER CATALYTIC
CONVERTER, CHECKING

EVALUATION OF DISPLAY GROUP 32 (2 OF 2)

Display field:
1/2 Possible cause Corrective action
Oxygen sensor z Un-metered air in intake z Check intake system for leaks and repair un-
values in area metered air, see INTAKE AIR SYSTEM,
range: 10.0 - CHECKING FOR LEAKS (UN-METERED
25.0 % AIR)
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z Fuel pressure too low Check fuel pressure regulator, see SYSTEM
z
PRESSURE, FUEL PRESSURE
REGULATOR AND RESIDUAL PRESSURE,
CHECKING
z Mass Air Flow (MAF) z Check Mass Air Flow (MAF) sensor, see MASS
sensor malfunctioning AIR FLOW (MAF) SENSOR - G70-,
CHECKING
z Oxygen sensor heating z Check oxygen sensor heating, see OXYGEN
malfunctioning SENSOR HEATING FOR OXYGEN
z Oxygen sensor
SENSORS BEFORE AND AFTER
malfunctioning CATALYTIC CONVERTER, CHECKING
z Fuel injector does not z Check fuel injectors, see FUEL INJECTORS,
open or opens only CHECKING
partially
z Evaporative Emission z Check Evaporative Emission (EVAP) Canister
(EVAP) Canister Purge Purge Regulator Valve, see EVAPORATIVE
Regulator Valve sticks EMISSION (EVAP) CANISTER PURGE
REGULATOR VALVE -N80-, CHECKING

Evaluation display group 33

EVALUATION OF DISPLAY GROUP 33

Display
field: 2 Possible cause Corrective action
Constant z Open circuit in wire 4 between z See CHECKING PRIMARY VOLTAGE
approx. oxygen sensor and control
0.450 V module
z Open circuit in wire 3 between
oxygen sensor and control
module
Constant z Oxygen sensor malfunctioning z Replace oxygen sensor
approx.
0.200 V
Larger than z Short circuit to B+ in wire 4 z Check oxygen sensor wiring and oxygen
1.100 V between oxygen sensor and sensor before catalytic converter, see
control module CHECKING OXYGEN SENSOR
Smaller than WIRING
z Short circuit to Ground in wire
0.150 V 4 between oxygen sensor and
control module

Checking primary voltage

z Disconnect 4-pin harness connector (black) to oxygen sensor before catalytic converter.
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Fig. 75: Disconnecting 4-Pin Harness Connector To Oxygen Sensor

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminals 3 and 4 for voltage measurement.

Fig. 76: Identifying Oxygen Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.
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z Switch ignition on.

z Specification: 0.400 - 0.500 V

z Switch ignition off.

If specified value is not obtained:

z Check oxygen sensor wiring.

If specified value is obtained:

z Replace oxygen sensor before catalytic converter -G39-.

Checking oxygen sensor wiring

z Disconnect 4-pin harness connector (black) to oxygen sensor before catalytic converter.

Fig. 77: Disconnecting 4-Pin Harness Connector To Oxygen Sensor

Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

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Fig. 78: Identifying Oxygen Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit.

OXYGEN SENSOR CIRCUIT TEST - OPENS

Harness connector terminal VAG1598/31 test box socket
3 51
4 7

z Repair open circuit if necessary.

z Check wires for short circuit to each other.

If wire connection is OK:

z Replace Engine Control Module (ECM), see ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen sensor aging, oxygen sensor before catalytic converter, checking

Special tools and shop equipment

z VAG1788/10 RPM adjuster

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Fig. 79: Identifying Special Tools - VAG1788/10 RPM Adjuster

Courtesy of AUDI OF AMERICA, INC.

z VAS5051 with VAG5051/1

or

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Fig. 80: Identifying Special Tools - VAS5051

Courtesy of AUDI OF AMERICA, INC.

z VAG1551 with VAG1551/3B

Test requirement

z Coolant temperature at least 80 °C (Display group 4, display field 3)

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

When indicated on display:

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Fig. 81: VAG 1551 Scan Tool Display - HO2S Aging, HO2S Before Catalytic Converter, Checking (1 Of
3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -4- to select "Basic Setting" and press -Q- button to confirm input.

When indicated on display:

Fig. 82: VAG 1551 Scan Tool Display - HO2S Aging, HO2S Before Catalytic Converter, Checking (2 Of
3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -3- and -4- to select "display group number 034" and press -Q- button to confirm input.

When indicated on display:

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Fig. 83: VAG 1551 Scan Tool Display - HO2S Aging, HO2S Before Catalytic Converter, Checking (3 Of
3)
Courtesy of AUDI OF AMERICA, INC.

z Adjust engine speed using VAG1788/10 to 1800 - 2200 RPM.

z Continue test as soon as display 4 indicates "Test ON."

NOTE: This process can take a few minutes.

DISPLAY GROUP 34: DIAGNOSTIC OXYGEN SENSOR AGING

Display fields
1 2 3 4
Display group 34: Diagnostic oxygen sensor aging
Display xxxx RPM xxx °C x.x s ---
Indicated Engine speed Exhaust Period duration Oxygen sensor Diagnostic
(RPM) temperature before catalytic converter condition
Work area 0 - 6800 70 - 850 °C 0 - 3.0 s Test OFF
Test ON
B1-S2 OK
B1-S2 not OK
Specified 1800 - 2200 more than 350 ° 0.0 - 2.7 s B1-S2 OK
value: RPM C
Note: If specified value is not obtained, see
CONTINUATION

Note for display field 2:

Calculated value from engine speed and engine load.

Note for display field 3 and 4:

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Period duration is the time between two oxygen sensor voltage jumps (e.g. rich - lean - rich) and is therefore a
measurement of the aging condition of the oxygen sensor. If the specified time is exceeded, display field 4 will
indicate = B1-S1 not OK.

Continuation

If specified value in display field 3 and 4 is not obtained:

z Road test vehicle in order to free oxygen sensor of possible residue and repeat test.

If specified value in display field 3 and 4 is not obtained, even after road test:

z Replace oxygen sensor before catalytic converter -G39-.

Oxygen sensor and oxygen sensor control behind catalytic converter, checking

NOTE: z Oxygen sensor control behind the catalytic converter is responsible for
final control correction. It is the primary sensor and can override the
signal from the oxygen sensor control before the catalytic converter.

Fig. 84: Oxygen Sensor Control Graph

Courtesy of AUDI OF AMERICA, INC.

z It corrects slight changes in the mixture (i.e. enrichment) via the oxygen
sensor before catalytic converter by holding the oxygen sensor control
before catalytic converter at its higher or lower limit for a specific time
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(duration). If this time is in the positive range (i.e. 50 ms), mixture is shifted
in the -enrich- direction. If this time is in the negative range (i.e. -50 ms),
mixture is shifted in the -lean- direction.

The 4-pin harness connector (brown) for the oxygen sensor behind catalytic and oxygen sensor heating is
located under a cover at vehicle floor.

Fig. 85: Locating HO2S 4-Pin Harness Connectors

Courtesy of AUDI OF AMERICA, INC.

Special tools and shop equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAG1788/10 RPM adjuster
z VAS5051 with VAG5051/1

or

z VAG1551 with VAG1551/3B

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Fig. 86: Identifying Special Tools And Shop Equipment

Courtesy of AUDI OF AMERICA, INC.

Test conditions

z Road test performed and DTC memory erased.

z Coolant Temperature less than 80 °C

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

When indicated on display:

Fig. 87: VAG 1551 Scan Tool Display - HO2S And HO2S Control Behind Catalytic Converter, Checking
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(1 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -4- to select "Basic Setting" and press -Q- button to confirm input.

NOTE: During Basic Setting, the Evaporative Emission (EVAP) canister purge regulator
valve (EVAP valve -N80-) is closed and the A/C compressor is switched off

When indicated on display:

Fig. 88: VAG 1551 Scan Tool Display - HO2S And HO2S Control Behind Catalytic Converter, Checking
(2 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -3- and -4- to select "display group number 034" and press -Q- button to confirm input.

When indicated on display:

Fig. 89: VAG 1551 Scan Tool Display - HO2S And HO2S Control Behind Catalytic Converter, Checking
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(3 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Adjust engine speed using VAG1788/10 to 2800 - 3200 RPM.

z Continue test as soon as display field 2 indicates an exhaust temperature of more than 350 °C.

NOTE: This process can take a few minutes.

z Press -C- button.

z Adjust engine speed using VAG1788/10 to 1800 - 2200 RPM.

When indicated on display:

Fig. 90: VAG 1551 Scan Tool Display - HO2S And HO2S Control Behind Catalytic Converter, Checking
(4 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -3- and -0- to select "display group number 030" and press -Q- button to confirm input.

When indicated on display:

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Fig. 91: VAG 1551 Scan Tool Display - HO2S And HO2S Control Behind Catalytic Converter, Checking
(5 Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Check oxygen sensor status for oxygen sensor behind catalytic converter in display field 2.

NOTE: "Oxygen sensor status" indicates status of oxygen sensor control and oxygen
sensor.

DISPLAY GROUP 30: OXYGEN SENSOR STATUS WITH ENGINE AT IDLE

Display fields
1 2 3 4
Display group 30: Oxygen sensor status with engine at idle
Display XXX XXX
Indicated Oxygen sensor status, bank 1, sensor 1 Oxygen sensor status bank 2, sensor 1
Work area 0 = off 0 = off1 = on
1 = on
Specified 111 110
value:
Note: If specified value is not obtained, see OXYGEN SENSOR HEATING FOR OXYGEN
SENSORS BEFORE AND AFTER CATALYTIC CONVERTER, CHECKING

Significance of 3 digit indication of display group 030

SIGNIFICANCE OF 3 DIGIT INDICATION OF DISPLAY GROUP 030

X X X Display field 2
1 Oxygen sensor control active
1 Operational readiness of oxygen sensor
1 Condition of oxygen sensor heating

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NOTE: z Oxygen sensor control of oxygen sensor behind catalytic converter (B1 -
S2) is not active without engine load.
z The first position of the 3 digit indication (heating) fluctuates between 0
and 1.

Checking oxygen sensor control behind catalytic converter

z Press -C- button.

When indicated on display:

Fig. 92: VAG 1551 Scan Tool Display - Checking Oxygen Sensor Control Behind Catalytic Converter (1
Of 2)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -3- and -7- to select "display group number 037" and press -Q- button to confirm input.

When indicated on display:

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Fig. 93: VAG 1551 Scan Tool Display - Checking Oxygen Sensor Control Behind Catalytic Converter (2
Of 2)
Courtesy of AUDI OF AMERICA, INC.

z Check oxygen sensor voltage in display field 2.

z Check duration of oxygen sensor control before catalytic converter in display field 3 and diagnostic result
in display field 4.

DISPLAY GROUP 37: DIAGNOSTIC OXYGEN SENSOR CONTROL SYSTEM

Display fields
1 2 3 4
Display group 37: Diagnostic oxygen sensor control system
Display xxx % x.xxx volts xxx ms ---
Indicated Engine Oxygen sensor voltage Duration of oxygen Diagnostic condition
load bank 2, sensor 1 sensor control before
catalytic converter,
bank 1
Work 15 - 0.000 - 1.000 V -1200 to 1200 ms Test OFF
area 150 % Test ON
System OK
System not OK
Specified 12 - 30 0.100 - 0.900 V -150 to 150 ms SYST. i.O.
value: %
Note: If specified value is not If value climbs to above If "System not OK" is
obtained: Evaluation display 300 ms, this indicates a displayed: Check DTC
field 2, see DISPLAY leaking exhaust system memory. See DIAGNOSTIC
FIELDS or malfunctioning TROUBLE CODE (DTC)
SPECIFICATION oxygen sensor MEMORY, CHECKING
AND ERASING .

Note for display field 3:

Oxygen sensor control behind catalytic converter is superior to oxygen sensor control before catalytic
converter and is the primary control. It corrects slight changes in the mixture (i.e. enrichment or thinning) by
holding the oxygen sensor control before catalytic converter at its higher or lower point for a specific time
(duration). If this time is in the positive range (i.e. 50 ms), mixture is shifted in the -enrich- direction. If this
time is in the negative range (i.e. 50 ms), mixture is shifted in the -lean- direction.

Evaluation display group 37

EVALUATION OF DISPLAY GROUP 37

Display
field: 2 Possible cause Corrective action
Constant z Open circuit in wire 4 z See CHECKING PRIMARY VOLTAGE
approx. 0.450 between oxygen sensor and
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V control module
z Open circuit in wire 3
between oxygen sensor and
control module
Larger than z Short circuit to B+ in wire 4 z Check oxygen sensor wiring and oxygen sensor
1.100 V between oxygen sensor and behind catalytic converter, see CHECKING
control module OXYGEN SENSOR WIRING
Smaller than z Short circuit to Ground in
0.150 V wire 4 between

oxygen sensor and control

module

Continuation

If specified value in display field 3 and 4 is not obtained:

z Road test vehicle in order to free oxygen sensor of possible residue and repeat test.

If specified value in display field 3 and 4 is not obtained, even after road test:

z Replace oxygen sensor before catalytic converter -G39-.

NOTE: If oxygen sensor voltage is OK and duration of oxygen sensor behind catalytic
converter is still above 1200 ms even after a road test, this indicates an aged
oxygen sensor before catalytic converter.

Checking primary voltage

z Disconnect 4-pin harness connector (brown) to oxygen sensor behind catalytic converter.

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Fig. 94: Disconnecting 4-Pin Harness Connector To Oxygen Sensor

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminals 3 and 4 for voltage measurement.

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Fig. 95: Identifying Oxygen Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Specification: 0.400 - 0.500 V

z Switch ignition off.

If specified value is not obtained:

z Check oxygen sensor wiring.

If specified value is obtained:

z Replace oxygen sensor behind catalytic converter

Checking oxygen sensor wiring

z Disconnect 4-pin harness connector (brown) to oxygen sensor behind catalytic converter.

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Fig. 96: Disconnecting 4-Pin Harness Connector To Oxygen Sensor

Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

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Fig. 97: Identifying Oxygen Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit.

HO2S BEHIND TWC CIRCUIT TEST - OPENS

Harness connector terminal VAG1598/31 test box socket
3 68
4 69

z Repair open circuit if necessary.

z Check wires for short circuit to each other.

If wire connection is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

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Oxygen sensor heating for oxygen sensors before and after catalytic converter, checking

Special tools and shop equipment

z VAG1526A
z VAG1594A
z VAG1598/31

Fig. 98: Identifying Special Tools And Shop Equipment

Courtesy of AUDI OF AMERICA, INC.

Test conditions

z Coolant Temperature less than 80 °C

z Fuse for oxygen sensor heating OK

See appropriate System Wiring Diagrams article.

Test sequence

z Disconnect 4-pin harness connector (black) to oxygen sensor before catalytic converter, or...

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Fig. 99: Disconnecting 4-Pin Harness Connector To Oxygen Sensor

Courtesy of AUDI OF AMERICA, INC.

z Disconnect 4-pin harness connector (brown) to oxygen sensor behind catalytic converter.

Fig. 100: Identifying Oxygen Sensor Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminals 1 and 2 of relevant connector for resistance measurement.
z Specified value at room temperature: 1 - 5 ohm

NOTE: At higher temperatures, resistance climbs sharply.

If specified value is not obtained:

z Replace oxygen sensor.

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If specified value is met:

z See CHECKING VOLTAGE SUPPLY OF OXYGEN SENSOR HEATING .

Checking voltage supply of oxygen sensor heating

z Connect multimeter between terminals 1 (B+) and 2 (Ground) for voltage measurement.

Fig. 101: Identifying Oxygen Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Start engine.
z Specification: approx. battery voltage, possibly fluctuating

NOTE: z At certain operating points, the ECM "pulses" the Ground for oxygen
sensor heating. This means that the Ground is switched on and off at
these points. It is therefore possible that the voltage displayed on the
tester will fluctuate.
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z The ECM switching oxygen sensor heating on and off can be observed, if
necessary, in the function "Read Measuring Value Block" display group
number 041.

If there is no voltage:

z Connect multimeter for voltage measurement as follows:

HO2S HEATING CIRCUIT TEST - VOLTAGE SUPPLY (TERMINAL 1)

Harness connector terminal Measure to
1 (B+) Vehicle Ground

z Operate starter briefly.

z Specification: approx. battery voltage

If there is no voltage again:

z Check wire connection from terminal 1 of connector to Fuel Pump (FP) relay via fuse for open circuit:

See appropriate System Wiring Diagrams article.

If voltage supply is OK:

Fig. 102: Identifying Oxygen Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.
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z Connect multimeter for voltage measurement as follows:

HO2S HEATING CIRCUIT TEST - VOLTAGE SUPPLY (TERMINAL 2)

Harness connector terminal Measure to
2 (Ground activation of Engine Control Module -ECM -) B+

z Start engine.
z Specification: approx. battery voltage, possibly fluctuating

z Switch ignition off.

If there is no voltage:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

Fig. 103: Identifying Oxygen Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connection for open circuit:

Oxygen sensor heating for oxygen sensor before catalytic converter (black connector)

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HO2S BEFORE TWC HEATING CIRCUIT TEST - OPENS

Harness connector terminal VAG1598/31 test box socket
2 5

Oxygen sensor heating for oxygen sensor behind catalytic converter (brown connector)

HHO2S BEHIND TWC HEATING CIRCUIT TEST - OPENS

Harness connector terminal VAG1598/31 test box socket
2 63

z Repair open circuit if necessary.

If wire connection is OK, but there is no Ground supply for oxygen sensor heating:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen sensor, removing and installing

Special tools and equipment

z 3337/9 socket wrench insert SW16

z Locking fluid G 052 112 A3

Fig. 104: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Procedure

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z Disconnect 4-pin harness connector of relevant oxygen sensor and lay it to side.

Fig. 105: Disconnecting 4-Pin Harness Connector Of Relevant Oxygen Sensor

Courtesy of AUDI OF AMERICA, INC.

NOTE: z Identification of oxygen sensor before catalytic converter: black

connector.
z Identification of oxygen sensor behind catalytic converter: brown
connector.

z Unscrew oxygen sensor using special tool 3337/9.

Note the following when installing:

NOTE: z Oxygen sensor wiring must always be secured in the same position when
installing so that contact with the exhaust pipe is avoided.
z Oxygen sensor threads are coated with an assembly paste. This paste
must not contact sensor openings.
z Tightening torque: 55 Nm

SECONDARY AIR INJECTION (AIR) VALVE, CHECKING

The secondary air system results in quicker heating and therefore earlier operating readiness of the catalytic
converter following cold start.

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Principle

Due to over-enrichment of the mixture during the cold start phase, there is an increased amount of un-
combusted carbon monoxide in the exhaust. Secondary Air Injection (AIR) improves secondary oxidation in the
catalytic converter and therefore reduces emissions. The heat produced by secondary oxidation greatly reduces
start -up time for the catalytic converter, therefore improving exhaust quality during the cold start phase
significantly.

Function

z In the cold start phase, the ECM - 2 - activates the secondary air pump - 12 - via the relay for secondary
air pump -1-. Air reaches the combination valve for Secondary Air Injection (AIR) - 10 -.
z Parallel to this, the Secondary Air Injection (AIR) solenoid valve - 3 - is activated, which permits
negative pressure to reach the combination valve for Secondary Air Injection (AIR) - 10 - and the
pressure unit for boost pressure regulation - 7 -. The combination valve for Secondary Air Injection (AIR)
thereby opens the path for secondary air to the exhaust channels of the cylinder head.

z To prevent unnecessary torque loss, secondary air is led around the turbocharger -8-. For this, the boost
pressure regulation pressure unit opens the boost pressure valve. The pressure unit, designed as a double
reservoir, has a vacuum connection for this on the low pressure side.

The following list pertains to Fig. 106 .

1. - Secondary Air Injection (AIR) pump relay -J299-

2. - Motronic Engine Control Module (ECM) -J220-
3. - Secondary Air Injection (AIR) solenoid valve -N112-
4. - Intake manifold
5. - Check-valve
z Installed position (light/dark half): Arrow points in direction of flow, as shown in figure

6. - Vacuum reservoir
7. - Pressure unit for boost pressure regulation
8. - Turbocharger
9. - Cylinder head
10. - Combination valve for Secondary Air Injection (AIR)
11. - Air filter
12. - Secondary Air Injection (AIR) pump motor -V101-

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Fig. 106: Identifying Secondary Air Injection (AIR) System Components

Courtesy of AUDI OF AMERICA, INC.

Secondary Air Injection (AIR) solenoid valve -N112-, checking

Special tools and shop equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31
z VAS5051 tester

or

z VAG1551 with VAG1551/3B

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Fig. 107: Identifying Special Tools And Shop Equipment

Courtesy of AUDI OF AMERICA, INC.

Component location, see COMPONENT LOCATIONS, OVERVIEW .

Test requirement

z Perform Output Diagnostic Test Mode

Checking internal resistance

z Unbolt bracket for Secondary Air Injection (AIR) solenoid valve from intake manifold.
z Disconnect harness connector from Secondary Air Injection (AIR) valve -N112-.

Fig. 108: Checking Secondary Air Injection (AIR) Solenoid Valve Internal Resistance
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter at valve for resistance measurement.

z Specified value: 25 - 35 ohm

z If specified value is not obtained, replace Secondary Air Injection (AIR) solenoid valve -N112-.

Checking voltage supply

z Disconnect harness connector from Secondary Air Injection (AIR) valve -N112-.
z Connect VAG1527B voltage tester as follows:

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Fig. 109: Identifying Secondary Air Injection (AIR) Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

SECONDARY AIR INJECTION (AIR) SOLENOID VALVE CIRCUIT TEST - VOLTAGE

SUPPLY
Harness connector terminal Measure to
1 Engine Ground

z Operate starter briefly (engine can also start).

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z LED must light

If LED does not light:

z Perform the following tests (marked with diamonds):

z Fuse for Secondary Air Injection (AIR) solenoid valve

Fig. 110: Fuse Holder

Courtesy of AUDI OF AMERICA, INC.

z Check wire connection from terminal 1 of connector to Fuel Pump (FP) relay via fuse for open
circuit:

Fig. 111: Identifying Secondary Air Injection (AIR) Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.
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See appropriate System Wiring Diagrams article.

z Check Fuel Pump (FP) relay. See FUEL PUMP (FP) RELAY -J17-, CHECKING ACTIVATION .

Checking activation

z Connect VAG1527B voltage tester as follows:

SECONDARY AIR INJECTION (AIR) SOLENOID VALVE CIRCUIT TEST - ACTIVATION

Harness connector terminal Measure to
2 B+

Fig. 112: Identifying Secondary Air Injection (AIR) Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Initiate Output Diagnostic Test Mode (DTM) and activate Secondary Air Injection (AIR) solenoid valve -
N112-. See OUTPUT DIAGNOSTIC TEST MODE (DTM) .

Indicated on display:

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Fig. 113: VAG 1551 Scan Tool Display - Secondary Air Injection (AIR) Solenoid Valve
Courtesy of AUDI OF AMERICA, INC.

z LED must blink.

If LED does not blink or if it remains constantly lit:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

Fig. 114: Identifying Secondary Air Injection (AIR) Solenoid Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground and B+:

SECONDARY AIR INJECTION (AIR) SOLENOID VALVE CIRCUIT TEST - OPENS/SHORTS

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Harness connector terminal VAG1598/31 test box socket

2 9

z Repair open circuit or short circuit if necessary.

If wire connection is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Secondary Air Injection (AIR) pump relay -J299 -, checking and activating

Special tools and shop equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31

Fig. 115: Identifying Special Tools And Shop Equipment

Courtesy of AUDI OF AMERICA, INC.

Checking and activating

Component location, see COMPONENT LOCATIONS, OVERVIEW .

z Initiate output Diagnostic Test Mode (DTM) and activate Secondary Air Injection (AIR) pump relay -
J299-. See OUTPUT DIAGNOSTIC TEST MODE (DTM) .
z Secondary Air Injection (AIR) pump relay -arrow- (under cover, left at bulkhead) must trigger and
the Secondary Air Injection (AIR) pump motor -V101- must run.

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Fig. 116: Identifying Secondary Air Injection (AIR) Pump Relay Location
Courtesy of AUDI OF AMERICA, INC.

A. - If relay does not trigger:

{ Check voltage supply of Secondary Air Injection (AIR) pump. See CHECKING VOLTAGE
SUPPLY OF SECONDARY AIR INJECTION (AIR) PUMP RELAY .
{ Check activation of Secondary Air Injection (AIR) pump relay. See CHECKING ACTIVATION
OF SECONDARY AIR INJECTION (AIR) PUMP RELAY .
B. - If relay triggers, but Secondary Air Injection (AIR) pump does not run:
{ Check voltage supply of Secondary Air Injection (AIR) pump motor. See CHECKING
VOLTAGE SUPPLY FOR SECONDARY AIR INJECTION (AIR) PUMP MOTOR .

Checking voltage supply of Secondary Air Injection (AIR) pump relay

z Remove Secondary Air Injection (AIR) pump relay

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Fig. 117: Identifying Secondary Air Injection (AIR) Pump Relay Terminals In Relay Carrier
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter for voltage measurement as follows.

SECONDARY AIR INJECTION (AIR) PUMP RELAY CIRCUIT TEST - VOLTAGE SUPPLY
(TERMINAL 2)
Relay carrier below cover, left at bulkhead terminal Measure to
2 Engine Ground

z Specification: approx. battery voltage

If specified value is not obtained:

z Perform the following tests marked with diamonds:

z Check fuse S131 (50 A) in main fuse box/battery.

z Check wire connection from B+ (terminal 30) to fuse S131 for Secondary Air Injection (AIR)
pump relay - J299- (below cover, left at bulkhead) for open circuit.

Fig. 118: Checking Fuse S131 (50 A) In Main Fuse Box/Battery

Courtesy of AUDI OF AMERICA, INC.

See appropriate System Wiring Diagrams article.

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Fig. 119: Identifying Secondary Air Injection (AIR) Pump Relay Terminals In Relay Carrier
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter for voltage measurement as follows.

SECONDARY AIR INJECTION (AIR) PUMP RELAY CIRCUIT TEST - VOLTAGE SUPPLY
(TERMINAL 6)
Relay carrier below cover, left at bulkhead terminal Measure to
6 Engine Ground

z Operate starter briefly (engine can also start).

z Specification: approx. battery voltage

If specified value is not obtained:

z Perform the following tests marked with diamonds:

z Check fuse S243 (in fuse holder, position 43)

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Fig. 120: Fuse Holder

Courtesy of AUDI OF AMERICA, INC.

z Check wire connection from B+ (terminal 30) to fuse S131 for Secondary Air Injection (AIR)
pump relay - J299- (below cover, left at bulkhead) for open circuit.

See appropriate System Wiring Diagrams article.

Checking activation of Secondary Air Injection (AIR) pump relay

z Switch ignition off.

z Remove Secondary Air Injection (AIR) pump relay.

Fig. 121: Identifying Secondary Air Injection (AIR) Pump Relay Terminals In Relay Carrier
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1527B voltage tester as follows:

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SECONDARY AIR INJECTION (AIR) PUMP RELAY CIRCUIT TEST - ACTIVATION

Relay carrier below cover, left at bulkhead terminal Measure to
4 B+

z Initiate Output Diagnostic Test Mode (DTM) and activate Secondary Air Injection (AIR) pump relay -
J299-. See OUTPUT DIAGNOSTIC TEST MODE (DTM) .
z LED must blink.

If LED does not blink:

z Switch ignition off.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
z Check the following wire connection for open circuit and short circuit to Ground and B+:

SECONDARY AIR INJECTION (AIR) PUMP RELAY CIRCUIT TEST - OPENS/SHORTS

Relay carrier below cover, left at bulkhead terminal VAG1598/31 test box socket
4 66

z Repair open circuit or short circuit if necessary.

If no malfunctions are detected:

z Replace Secondary Air Injection (AIR) pump relay -J299-.

Fig. 122: Identifying Secondary Air Injection (AIR) Pump Relay Terminals In Relay Carrier
Courtesy of AUDI OF AMERICA, INC.

Checking voltage supply for Secondary Air Injection (AIR) pump motor

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z Remove center noise insulation (arrows).

Fig. 123: Removing Center Noise Insulation

Courtesy of AUDI OF AMERICA, INC.

z Remove connector for Secondary Air Injection (AIR) pump motor -V101-.

Fig. 124: Removing Connector For Secondary Air Injection (AIR) Pump Motor -V101-
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1527B voltage tester to connector terminals 1 and 2.

z Initiate Output Diagnostic Test Mode (DTM) and activate Secondary Air Injection (AIR) pump relay -
J299-. See OUTPUT DIAGNOSTIC TEST MODE (DTM) .
z LED must blink.

If LED does not blink:

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z Perform the following tests marked with diamonds:

z Check wire connection from connector at Secondary Air Injection (AIR) pump motor - V101- to
Secondary Air Injection (AIR) pump relay -J299- (in relay carrier below cover, left at bulkhead) for
open circuit:

See appropriate System Wiring Diagrams article.

z Check wire connection from connector at Secondary Air Injection (AIR) pump motor - V101- to Ground
point in engine compartment, left, for open circuit:

See appropriate System Wiring Diagrams article.

If no malfunctions are detected:

z Replace Secondary Air Injection (AIR) pump motor -V101-.

TANK VENTILATION, CHECKING

Evaporative Emission (EVAP) canister purge regulator valve -N80-, checking

Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1
{ or

z VAG1551 with VAG1551/3B

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Fig. 125: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Checking for proper seal

When there is no current, the Evaporative Emission (EVAP) canister purge regulator valve - N80- is closed.

z Disconnect hoses from EVAP valve; harness connector remains connected.

z Attach auxiliary hose to one connection of EVAP valve.
z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

z Initiate output DTM and activate Evaporative Emission (EVAP) canister purge regulator valve -N80-
(tank ventilation valve). See OUTPUT DIAGNOSTIC TEST MODE (DTM) .

Indicated on display:

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Fig. 126: VAG 1551 Scan Tool Display - Emission (EVAP) Canister Purge Regulator Valve
Courtesy of AUDI OF AMERICA, INC.

Valve must click...

...and must open and close (can be tested by blowing into auxiliary hose).

If valve does not click:

z Check internal resistance of EVAP valve.

If valve does not open and close properly:

z Replace Evaporative Emission (EVAP) canister purge regulator valve -N80-

Checking internal resistance

z Disconnect connector at EVAP valve.

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Fig. 127: Checking EVAP Canister Purge Regulator Valve Internal Resistance
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter at valve for resistance measurement.

z Specified value: 22 - 30 ohm

If specified value is not obtained:

z Replace Evaporative Emission (EVAP) canister purge regulator valve -N80-.

If specified value is obtained:

z See CHECKING VOLTAGE SUPPLY .

Checking voltage supply

NOTE: Voltage is supplied to the EVAP valve via the Fuel Pump (FP) relay.

Test requirement

z Fuse for the EVAP valve OK

z Disconnect connector at EVAP valve.

Fig. 128: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1527B voltage tester as follows:

EVAP CANISTER PURGE REGULATOR VALVE CIRCUIT TEST - VOLTAGE SUPPLY

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Harness connector terminal Measure to

1 Engine Ground

z Operate starter briefly.

z LED must light.

If LED does not light:

z Check wire connection from terminal 1 to Fuel Pump (FP) relay via fuse for open circuit.

See appropriate System Wiring Diagrams article.

z Repair open circuit if necessary.

If wire connection is OK:

z Check Fuel Pump (FP) relay. See FUEL PUMP (FP) RELAY -J17-, CHECKING ACTIVATION .

If LED lights:

z Go to CHECKING ACTIVATION .

Checking activation

z Connect VAG1527B voltage tester to connector terminals 1 (B+) and 2.

Fig. 129: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Initiate output DTM and activate Evaporative Emission (EVAP) canister purge regulator valve -N80-. See
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OUTPUT DIAGNOSTIC TEST MODE (DTM) .

z LED must blink

If LED does not blink or if it remains constantly lit:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

Fig. 130: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connection for open circuit and short circuit to Ground and B+:

EVAP CANISTER PURGE REGULATOR VALVE CIRCUIT TEST - ACTIVATION

Harness connector terminal VAG1598/31 test box socket
2 64

z Repair open circuit or short circuit if necessary.

If wire connection is OK:

z Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

ELECTRONIC ACCELERATOR (E-GAS) POWER CONTROL, CHECKING

E-Gas system, function

For E-Gas, the throttle valve is not operated by a cable from the accelerator pedal. There is no mechanical
connection between the accelerator pedal and the throttle valve.

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The position of the accelerator pedal is communicated to the Engine Control Module (ECM) via two sensors for
accelerator pedal position (variable resistances; stored in one housing) that are connected with the accelerator
pedal.

The accelerator pedal position (driver's intention) is a main input measure value for the ECM.

Operation of the throttle valve occurs via an electric motor (throttle valve actuator) in the throttle valve control
module. This is true across the entire engine speed and engine load spectrum.

The throttle valve is operated by the throttle valve actuator according to the instructions of the ECM.

With ignition switched on and engine off, the ECM activates the throttle valve actuator precisely according to
the sensor for accelerator pedal position. This means, if the accelerator pedal is depressed half way, the throttle
valve actuator opens the throttle valve to the same degree; i.e. throttle valve would be opened half way.

With engine running (under load), the ECM can open or close the throttle valve independently of the sensor for
accelerator pedal position.

This means, for example, that the throttle valve could be fully opened even though the accelerator pedal has
only been depressed half way. This has the advantage of preventing torque losses at the throttle valve.

In addition to this, it results in significantly better values relative to emissions and consumption under certain
load conditions.

The required engine torque can be achieved by the Engine Control Module (ECM) via the optimal combination
of throttle valve diameter and boost pressure.

It would be incorrect to think that "E-Gas" consists of only one or two components. E -Gas is much more of a
system containing all components that contribute to recognizing, controlling and monitoring the position of the
throttle valve, e.g. sensor for accelerator pedal position, throttle valve control module, EPC warning lamp,
Engine Control Module (ECM).

Electronic Power Control (EPC) warning lamp (malfunction indicator lamp for electronic accelerator -E-Gas) in
instrument cluster, significance

Location of EPC warning lamp

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Fig. 131: Location Of EPC Warning Lamp

Courtesy of AUDI OF AMERICA, INC.

Engine Control Module (ECM) checks all components that are important for function of the E -Gas system after
ignition is switched on.

During the test of these components, the ECM switches the EPC warning lamp on.

If malfunctions are recognized in the E-Gas system during operation of the engine, the ECM switches on the
EPC warning lamp in instrument cluster. (These malfunctions are listed in the DTC table). An entry is made in
DTC memory at the same time.

Malfunction light for power accelerator activation -K132-, checking

NOTE: The malfunction light for power accelerator activation -K132- is also called the
EPC warning lamp.

Special tools and equipment

z VAG1594A

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Fig. 132: Identifying Special Tools And Equipment - VAG1594A

Courtesy of AUDI OF AMERICA, INC.

z VAG1598/31

Fig. 133: Identifying Special Tools And Equipment - VAG1598/31

Courtesy of AUDI OF AMERICA, INC.

Functional test of warning lamp

z Switch ignition on.

z EPC warning lamp must light up

A. - malfunction light for power accelerator activation (EPC warning lamp) -K132- does not light up
{ Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND

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COMPONENT TEST USING VAG1598/31 TEST BOX .

{ Bridge sockets 1 and 48 of test box.
{ Switch ignition on.
z Warning lamp must light

If warning lamp does not light:

{ Switch ignition off.

{ Remove instrument cluster and check bulb and its voltage supply:

See INSTRUMENTS .

If no malfunctions are detected:

{ Check the following wire connection for open circuit and short circuit to B+:

INSTRUMENT CLUSTER CIRCUIT SPECIFICATION

Test box VAG1598/31 socket Instrument cluster ter
48 See appropriate System Wiring Diagrams a

{ Repair open circuit or short circuit if necessary.

If wire connection is OK:

{ Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM)
(WITHOUT METAL ANTI-THEFT HOUSING), REPLACING .
B. - malfunction light for power accelerator activation -K132- remains lit after engine start
{ Check DTC memory of Engine Control Module (ECM).

If no DTCs are stored:

{ Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
{ Check the following wire connection for short circuit to Ground:

INSTRUMENT CLUSTER CIRCUIT SPECIFICATION

Test box VAG1598/31 socket Instrument cluster ter
48 See appropriate System Wiring Diagrams a

{ Repair short circuit if necessary.

If wire connection is OK:

{ Replace Engine Control Module (ECM). See ENGINE CONTROL MODULE (ECM)
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(WITHOUT METAL ANTI-THEFT HOUSING), REPLACING .

Throttle valve control module -J338-, checking

The following components are located in the housing for the throttle valve control module:

z Throttle drive (power accelerator actuation) - G186-. (This is an electric motor that is activated by the
ECM. This electric motor opens the throttle valve against spring pressure.)
z Angle sensor -1- for throttle drive (power accelerator actuation) -G187-
z Angle sensor -2- for throttle drive (power accelerator actuation) -G188-

NOTE: z The housing for the throttle valve control module must not be opened.
z The angle sensors are designed as potentiometers (variable resistances).
They communicate the position of the throttle valve to the Engine Control
Module (ECM) fully independent of each other.
z The potentiometers cannot be mechanically adjusted. Adjustments are
made in Basic Setting (function 04) using the VAS5051 tester or VAG1551
Scan Tool.

Throttle valve control module, adaptation

During adaptation with ignition switched on and engine off, the Engine Control Module (ECM) learns the
various positions of the throttle valve. These positions are stored in the control module. The return
communication regarding the position of the throttle valve occurs via the two angle sensors for throttle drive.

An adaptation must always be performed when the throttle valve control module -J338- or the Engine Control
Module (ECM) are removed and installed (or replaced) or if voltage supply to the Engine Control Module
(ECM) is interrupted.

The learning process (adaptation) occurs:

z Via initiation of Basic Setting (function 04) display group 60 with ignition on.
z Automatically if the ignition is switched on for at least 6 seconds without operating starter and accelerator
pedal and the Engine Control Module (ECM) recognizes "adaptation required." (There will be no
notification of whether adaptation was successful or not however). Adaptation required is recognized if
stored voltage values from the angle sensors do not match actual measured voltage values within a certain
tolerance range.

NOTE: Engine will not start during automatic adaptation.

Special tools and equipment

z VAS5051 with VAG5051/1

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Fig. 134: Identifying Special Tool VAS 5051

Courtesy of AUDI OF AMERICA, INC.

or

z VAG1551 with VAG1551/3B

Requirements

z No DTCs in DTC memory; check DTC memory. See DIAGNOSTIC TROUBLE CODE (DTC)
MEMORY, CHECKING AND ERASING .
z Engine not running, ignition switched on
z Accelerator pedal not depressed
z Coolant Temperature more than 5 °C but less than 100 °C. (Read Measuring Value Block, display group
4, display field 3)
z Intake Air Temperature (IAT) less than 100 °C (Read Measuring Value Block, display group 4, display
field 4)
z Supply voltage for ECM larger than 11 V; checking. See CONTROL MODULE VOLTAGE SUPPLY,
CHECKING .

Procedure

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

When indicated on display:

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Fig. 135: VAG 1551 Scan Tool Display - Throttle Valve Control Module, Adaptation (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -4- to select "Basic Setting" and press -Q- button to confirm input.

When indicated on display:

Fig. 136: VAG 1551 Scan Tool Display - Throttle Valve Control Module, Adaptation (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -6- and -0- to select "display group number 060" and press -Q- button to confirm input.

After pressing Q button, throttle valve actuator will be switched on mechanically (i.e. without current).

In this condition, the throttle valve will be drawn into an emergency position by a mechanical spring, which is
located in the throttle valve control module. The values that both angle sensors deliver in this emergency
position are stored by the Engine Control Module (ECM).

After this, the throttle valve is opened by a specific value. Once this value is reached, the throttle valve actuator
will be switched on again without current. Then the mechanical spring closes the throttle valve to the previously
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learned emergency position within a certain time (spring test).

Finally, the throttle valve is closed by the throttle valve actuator; the values that the angle sensors deliver in the
throttle valve control module are stored in the ECM.

If the ECM switches the throttle valve actuator during driving operation without current, this is indicated by a
heightened, uneven idle speed. The engine accepts gas only after great delay.

Indicated on display:

Fig. 137: VAG 1551 Scan Tool Display - Throttle Valve Control Module, Adaptation (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Check specified values for throttle valve control module in display fields 3 and 4.

DISPLAY GROUP 60: ADAPTATION OF THROTTLE VALVE CONTROL MODULE

Display fields
1 2 3 4
Display group 60: Adaptation of throttle valve control module
Display xx % xx % --- ---
Indicated Throttle valve Throttle valve Adaptation step counter Adaptation
angle (angle angle (angle condition
sensor 1) sensor 2)
Work area min.: 0 % min.: 0 % 0-8 ADP running
max.: 100% max.: 100% ADP OK
ADP ERROR
Specified 3 - 93 % 97 - 3 % 8 ADP OK
value:
Note: During adaptation, adaptation If specified value is
step counter must run from 0 to 8. not obtained: see
(Some numbers may be skipped) Note below

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NOTE: The abbreviation "ADP" in display field 4 stands for "Adaptation."

NOTE: Possible reasons for the control module to abort the adaptation procedure:

z Throttle valve cannot be closed completely (e.g. contamination).

z Battery voltage is too low.
z Throttle valve control module or wire connection is malfunctioning.
z Engine is started during adaptation or accelerator pedal is operated.
z Tension of throttle valve housing (check bolts).

z End Basic Setting of engine by pressing --> button.

Fig. 138: VAG 1551 Scan Tool Display - Throttle Valve Control Module, Adaptation (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

Indicated on display (function selection):

Angle sensor for throttle drive, checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

or

z VAG1551 with VAG1551/3B

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Fig. 139: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Test sequence

Angle sensor 1 for throttle drive (power accelerator actuation) -G187- and angle sensor 1 for throttle drive
(power accelerator actuation) - G188- inform the Engine Control Module (ECM) about the position of the
throttle valve. Both angle sensors are located in the throttle valve control module.

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS . Ignition
must remain switched on for this.

When indicated on display:

Fig. 140: VAG 1551 Scan Tool Display - Angle Sensor For Throttle Drive, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

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z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 141: VAG 1551 Scan Tool Display - Angle Sensor For Throttle Drive, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -6- and -2- to select "display group number 062" and press -Q- button to confirm input.

Indicated on display:

Fig. 142: VAG 1551 Scan Tool Display - Angle Sensor For Throttle Drive, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check specified value for E -Gas potentiometer voltages.

DISPLAY GROUP 62: E -GAS POTENTIOMETER VOLTAGES

Display fields
1 2 3 4
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Display group 62: E -Gas potentiometer voltages

Display xx % xx % xx % xx %
Indicated Throttle valve angle Throttle valve angle Sensor for Sensor 2 for
(angle sensor 1) (angle sensor 2) pedal position pedal position
Work area min.: 0 % min.: 0 % min.: 0 % min.: 0 %
max.: 100 % max.: 100 % max.: 100 % max.: 100 %
Specified value: 3 - 93 % 97 - 3 % 12 - 97 % 4 - 49 %

NOTE: Engine Control Module (ECM) calculates the voltage values of the angle
sensors in percent relative to 5 volts and displays these percentage values. (5
volts supply voltage represents 100 %).

z Observe display field 1 and 2.

z Slowly depress accelerator pedal completely.

Percent indication in display field 1 must climb uniformly. The tolerance range 3 - 93 % is not used completely
during this.

Percent indication in display field 2 must decrease uniformly. The tolerance range 97 - 3 % is not used
completely during this.

NOTE: z The reason that the indication in display field 1 climbs but the indication in
display field 2 decreases, is due to the inverse relationship of the
potentiometers (angle sensors) in the throttle valve control module.
z This means that the voltage of the one angle sensor runs toward 5 volts.
(The more the throttle valve is opened, the larger the voltage; percent
indication climbs).
z The voltage of angle sensor 2 runs from 5 volts toward 0 volts. (The more
the throttle valve is opened, the smaller the voltage; percent indication
decreases).

If indications do not resemble description:

z Check voltage supply and wire connections of throttle valve control module. See CHECK VOLTAGE
SUPPLY THROTTLE VALVE CONTROL MODULE . Pay particular attention to harness
connectors that could be loose or corroded.
z Check accelerator pedal position sensor. See ACCELERATOR PEDAL POSITION SENSORS,
CHECKING .

Check voltage supply throttle valve control module

z Disconnect connector from throttle valve control module.

z Switch ignition on.

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Fig. 143: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter for voltage measurement as follows:

THROTTLE VALVE CONTROL MODULE CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector terminal Specified value
2 + Ground approx. 5 V
2+6 approx. 5 V

If specified values are obtained:

z Also check signal wires and activation wires of throttle valve actuator. See CHECKING WIRE
CONNECTIONS .

If specified values are not obtained:

z Check wire connections from Engine Control Module (ECM) to throttle valve control module. See
CHECKING WIRE CONNECTIONS .

Checking wire connections

z Disconnect connector from throttle valve control module.

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

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Fig. 144: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground and B+:

THROTTLE VALVE CONTROL MODULE CIRCUIT TEST - OPENS/SHORTS

Harness connector terminal VAG1598/31 test box socket
1 92
2 83
3 117
4 84
5 118
6 91

z Repair open circuit or short circuit if necessary.

If no malfunctions are found in wires:

z Replace throttle valve control module.

Accelerator pedal position sensors, checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

or
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z VAG1551 with VAG1551/3B

Fig. 145: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Test sequence

Both the Throttle Position (TP) sensor -G79- and the Sender -2- for accelerator pedal position - G185- are
located at the accelerator pedal and communicate the driver's intentions to the ECM completely independently
of each other. Both sensors are stored in one housing.

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

When indicated on display:

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Fig. 146: VAG 1551 Scan Tool Display - Accelerator Pedal Position Sensors, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 147: VAG 1551 Scan Tool Display - Accelerator Pedal Position Sensors, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -6- and -2- to select "display group number 062" and press -Q- button to confirm input.

Indicated on display:

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Fig. 148: VAG 1551 Scan Tool Display - Accelerator Pedal Position Sensors, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check specified value for E -Gas potentiometer voltages.

DISPLAY GROUP 62: E -GAS POTENTIOMETER VOLTAGES

Display fields
1 2 3 4
Display group 62: E -Gas potentiometer voltages
Display xx % xx % xx % xx %
Indicated Throttle valve angle Throttle valve angle Sensor for Sensor 2 for
(angle sensor 1) (angle sensor 2) pedal position pedal position
Work area min.: 0 % min.: 0 % min.: 0 % min.: 0 %
max.: 100 % max.: 100 % max.: 100 % max.: 100 %
Specified value: 3 - 93 % 97 - 3 % 12 - 97 % 4 - 49 %

NOTE: Engine Control Module (ECM) calculates the voltage values of the angle
sensors in percent relative to 5 volts and displays these percentage values. (5
volts supply voltage represents 100 %).

z Observe display field 3 and 4.

z Slowly depress accelerator pedal completely.

Percent indication in display field 3 must climb uniformly. The tolerance range 12 - 97 % is not used
completely during this.

Percent indication in display field 4 must also climb uniformly. The tolerance range 4 - 49 % is not used
completely during this.

NOTE: The indicated value in display field 3 must always be approx. twice as large as
the value in display field 4.
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If indications do not resemble description:

z Check voltage supply and wire connections of sensor for accelerator pedal position. See CHECKING
VOLTAGE SUPPLY OF THE SENSORS FOR ACCELERATOR PEDAL POSITION .

Checking voltage supply of the sensors for accelerator pedal position

z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Disconnect harness connector for accelerator pedal position sensor.

z Switch ignition on.

Fig. 149: Identifying Accelerator Pedal Position Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter for voltage measurement as follows:

ACCELERATOR PEDAL POSITION CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector terminal Specified value
1 + Ground approx. 5 V
1+5 approx. 5 V
2 + Ground approx. 5 V
2+3 approx. 5 V

If specified values are obtained:

z Also check signal wires.

If specified values are not obtained:

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z Check wire connections from Engine Control Module (ECM) to sensors for accelerator pedal position.

Checking wire connections

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM, see WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

Fig. 150: Identifying Accelerator Pedal Position Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connection for open circuit and short circuit to Ground and B+:

ACCELERATOR PEDAL POSITION CIRCUIT TEST - OPENS/SHORTS

Harness connector terminal VAG1598/31 test box socket
1 72
2 73
3 36
4 35
5 33
6 34

z Repair open circuit or short circuit if necessary.

If no malfunctions are found in wires:

z Replace accelerator pedal position sensor.

See REMOVING AND INSTALLING ACCELERATOR PEDAL MODULE WITH THROTTLE

POSITION (TP) SENSOR -G79- AND SENDER -2-FOR ACCELERATOR PEDAL POSITION -G185- .

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NOTE: For vehicles with automatic/variable transmission, the kick down function must
be learned. See KICK DOWN FUNCTION, LEARNING .

Kick down function, learning

If the sensor for accelerator pedal position or the Engine Control Module (ECM) is replaced on a vehicle with
automatic transmission, the kick down function must be learned by the ECM.

Requirements

z No DTCs in DTC memory; check DTC memory. See DIAGNOSTIC TROUBLE CODE (DTC)
MEMORY, CHECKING AND ERASING .
z Engine not running, ignition switched on.

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

When indicated on display:

Fig. 151: VAG 1551 Scan Tool Display - Kick Down Function, Learning (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -4- to select "Basic Setting" and press -Q- button to confirm input.

When indicated on display:

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Fig. 152: VAG 1551 Scan Tool Display - Kick Down Function, Learning (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -6- and -3- to select "display group number 063" and press -Q- button to confirm input.

When indicated on display:

Fig. 153: VAG 1551 Scan Tool Display - Kick Down Function, Learning (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

NOTE: There will be a prompt: "Operate kick down"

z Depress accelerator pedal completely, past kick down point, and hold down.

NOTE: During the learning of the kick down point, the VAG1551 will display "Kick down
ADP in progress." After successful learning of kick down point, the VAG1551
will display "Kick down ADP OK."

z Check specified value in display field 4.

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DISPLAY GROUP 63: LEARNING KICK DOWN FUNCTION

Display fields
1 2 3 4
Display group 63: Learning kick down function
Display xx % xx % ---
Indicated Sensor for Sensor 2 Adaptation condition
pedal for
position pedal
position
Work area 0 - 100 % 0 - 100 % Kick down operate
ADP in progress
ADP OK
ADP ERROR
Specified 12 - 97 % 4 - 49 % Kick down ADP OK
value:
Note: If "ADP ERROR." is displayed: Check DTC memory. See
DIAGNOSTIC TROUBLE CODE (DTC) MEMORY,
CHECKING AND ERASING .

If specified value "ADP OK" is obtained:

z Press --> button.

Indicated on display (function selection):

Fig. 154: VAG 1551 Scan Tool Display - Kick Down Function, Learning (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -6- to select "end output."

VACUUM DIAGRAM

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The following list pertains to Fig. 155 .

1. - From fuel tank

2. - EVAP canister
z EVAP canister is located at rear, below at vehicle floor, below a cover

3. - Check-valve for EVAP canister

z Between EVAP canister and intake manifold before turbocharger

z Installed position (light/dark half): arrow points in direction of flow, as shown

4. - Turbocharger
5. - Pressure unit for boost pressure regulation
6. - Mechanical recirculation valve
7. - Brake booster
8. - Check-valve
z Between brake booster and intake manifold

z Installed position (light/dark half): arrow points in direction of flow, as shown

9. - Wastegate Bypass Regulator Valve -N75-

10. - Mass Air Flow (MAF) sensor -G70-
11. - Air filter
12. - Pressure regulation valve for crankcase ventilation
13. - Vacuum reservoir
z Bolted on at cylinder head

14. - Fuel pressure regulator

15. - Intake manifold
z With Intake Air Temperature (IAT) sensor -G42-

16. - Check-valve
z Installed position (light/dark half): arrow points in direction of flow, as shown

17. - Turbocharger boost pressure recirculation valve -N249-

18. - Secondary Air Injection (AIR) solenoid valve -N112-
19. - Crankcase ventilation
20. - Secondary Air Injection (AIR) pump motor -V101-
21. - Throttle valve control module -J338 -
22. - Charge Air Cooler
z With charge air pressure sensor -G31-

23. - Check-valve
z Between EVAP canister and intake manifold

z Installed position (light/dark half): arrow points in direction of flow, as shown

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Fig. 155: Identifying Engine Vacuum Diagram

Courtesy of AUDI OF AMERICA, INC.

AUXILIARY SIGNALS, CHECKING

Engine speed signal, checking

NOTE: z The signal is generated by the engine speed (RPM) sensor -G28-
processed in the Engine Control Module (ECM) and directed to various
parts of the electronic system (for example, control module for A/C or
ABS / EDS) from terminal 37 of the ECM. Engine speed signal and wire
connections are monitored by these systems.
z Checking engine speed signal:

See appropriate System Wiring Diagrams article.

Consumption signal for board computer, checking

NOTE: z The consumption signal is calculated by the ECM from the injection time
and directed to the on board computer via terminal 81 of the ECM.
z Checking consumption signal:

See INSTRUMENTS .

Vehicle Speed Signal (VSS), checking

Special tools and equipment

z VAG1526A
z VAG1527B

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z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1
{ or

z VAG1551 with VAG1551/3B

Fig. 156: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

NOTE: z The vehicle speed signal is generated by the Vehicle Speed Sensor (VSS) -
G68- (at transmission) and processed in the instrument cluster.
z The processed signal enters at terminal 54 of the ECM and is used for idle
stabilization and tip-in shock reduction during shifting.

Test requirement

z Function and display of speedometer OK.

See INSTRUMENTS .

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01.See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

WARNING: To reduce the risk of accident during road tests, observe safety
precautions. See MULTIPORT FUEL INJECTION (MFI) .
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When indicated on display:

Fig. 157: VAG 1551 Scan Tool Display - Vehicle Speed Signal (VSS), Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 158: VAG 1551 Scan Tool Display - Vehicle Speed Signal (VSS), Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -0- and -5- to select "display group number 005" and press -Q- button to confirm input.

Indicated on display:

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Fig. 159: VAG 1551 Scan Tool Display - Vehicle Speed Signal (VSS), Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Determine via road test whether vehicle speed is displayed in display field 3.
z If vehicle speed is not displayed, lift vehicle (if possible using a vehicle lift) until front left wheel is free.
z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
z Connect VAG1527B voltage tester to sockets 3 (B+) and 54 (VSS) of VAG1598/31 test box.
z Switch ignition on and turn front left wheel by hand.
z LED must blink (very brief blink signal)

If LED does not blink:

z Check the following wire connection for open circuit and short circuit to Ground and B+:

VEHICLE SPEED SIGNAL (VSS) CIRCUIT TEST - OPENS/SHORTS

Test box VAG1598/31 socket Instrument cluster terminal
54 See appropriate System Wiring Diagrams article.

z Repair open circuit or short circuit if necessary.

A/C compressor switch-off, checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1
{ or

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z VAG1551 with VAG1551/3B

Fig. 160: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

NOTE: z The A/C compressor signal communicates to the ECM that the compressor
will be switched on in 140 ms.
z The ECM can switch off the A/C compressor via the same wire connection.

Engine Control Module (ECM) switches off A/C compressor:

z During hard acceleration (Wide Open Throttle 1st gear)

z In emergency mode (emergency operation)
z After initiating Basic Setting (function 04)

Test conditions

z A/C system OK
z Not DTC in DTC memory of Engine Control Module (ECM)
z Vehicle at room temperature (warmer than +15 °C)

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

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When indicated on display:

Fig. 161: VAG 1551 Scan Tool Display - A/C Compressor Switch-Off, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 162: VAG 1551 Scan Tool Display - A/C Compressor Switch-Off, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -5- and -0- to select "display group number 050" and press -Q- button to confirm input.

Indicated on display: (1 - 4 display fields)

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Fig. 163: VAG 1551 Scan Tool Display - A/C Compressor Switch-Off, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Switch A/C system off.

z Specified value in display field 4: Compr. OFF

z Switch A/C system on using "Auto" button and adjust A/C system to maximum cooling or heating power.

Compressor must run.

z Specified value in display field 4: Compr. ON

z Fully depress accelerator pedal abruptly and then release (brief acceleration).
z Specified value in display field 4: Display switches for a few seconds from "Compr. ON" to
"Compr. OFF" (compressor switch - off for vehicle acceleration)

If indications do not resemble description:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
z Check the following wire connection for open circuit and short circuit to Ground and B+:

A/C CONTROL HEAD -E87- TERMINAL SPECIFICATION

Test box VAG1598/31 socket A/C control head -E87- terminal
41 See appropriate System Wiring Diagrams article.

z Repair open circuit or short circuit if necessary.

z If there are no malfunctions in the wiring, check function of A/C system.

See ON BOARD DIAGNOSTIC (OBD) .

Brake light switch and brake pedal switch, checking

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Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

or

z VAG1551 with VAG1551/3B

Fig. 164: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Test sequence

NOTE: For safety reasons, the instruction from the accelerator pedal sensor
(potentiometer) to the ECM to open the throttle valve is suppressed when brake
is being operated. This requires the brake light switch signal and also the brake
pedal switch signal in the control module. If brake pedal is operated with
accelerator pedal constantly depressed, engine is immediately regulated down
to idle speed. A malfunctioning switch can lead to undesired regulation.

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

When indicated on display:

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Fig. 165: VAG 1551 Scan Tool Display - Brake Light Switch And Brake Pedal Switch, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 166: VAG 1551 Scan Tool Display - Brake Light Switch And Brake Pedal Switch, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -6- and -6- to select "display group number 066" and press -Q- button to confirm input.

Indicated on display:

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Fig. 167: VAG 1551 Scan Tool Display - Brake Light Switch And Brake Pedal Switch, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check brake light/brake pedal switch in display field 2.

DISPLAY GROUP 66: SIGNALS TO ENGINE CONTROL MODULE (ECM)

Display fields
1 2 3 4
Display group 66: Signals to Engine Control Module (ECM)
Display xxx km/h XXXX xxx km/h XXXX
Indicated ACTUAL Switch positions SPECIFIED Switch
speed speed positions
Work area XX00 XX11
Specified XX00 (with brake pedal not
value: operated)
XX11 (with brake pedal operated)
Note: Value: X = no significance.
Switch points slightly offset

If indications do not resemble description:

Check switch

z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Disconnect harness connector at brake light/brake pedal switch.

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Fig. 168: Identifying Connector Terminals At Brake Light/Brake Pedal Switch

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminals 1 and 4 for resistance measurement.

z Specification: INFINITY ohm (no continuity)

z Depress accelerator pedal.

z Specified value: approx. 0 ohm

z Connect multimeter between terminals 2 and 3 for resistance measurement.

z Specified value: approx. 0 ohm

z Depress accelerator pedal.

z Specification: INFINITY ohm(no continuity)

If specified values are not obtained:

z Replace brake light/brake pedal switch.

If specified values are obtained:

Checking voltage supply

z Connect VAG1527B voltage tester as follows:

BRAKE LIGHT SWITCH AND BRAKE PEDAL SWITCH CIRCUIT TEST - VOLTAGE
SUPPLY (TERMINAL 1)
Harness connector terminal Measure to
1 Chassis Ground

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Fig. 169: Identifying Brake Light/Brake Pedal Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z LED must light.

BRAKE LIGHT SWITCH AND BRAKE PEDAL SWITCH CIRCUIT TEST - VOLTAGE
SUPPLY (TERMINAL 2)
Harness connector terminal Measure to
2 Chassis Ground

z Switch ignition on.

z LED must light

If LED does not light:

z Check wire connection from terminal 1 or 2 of connector for open circuit and short circuit to Ground:

See appropriate System Wiring Diagrams article.

z Repair open circuit or short circuit if necessary.

If LED lights, go to CHECKING ACTIVATION .

Checking activation

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

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Fig. 170: Identifying Brake Light/Brake Pedal Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground and B+:

BRAKE LIGHT SWITCH AND BRAKE PEDAL SWITCH CIRCUIT TEST - ACTIVATION
Harness connector terminal VAG1598/31 test box socket
3 55
4 56

z Repair open circuit or short circuit if necessary.

Clutch vacuum vent valve switch -F36-, checking

Special tools and equipment

z VAG1526A
z VAG1527B
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1
{ or

z VAG1551 with VAG1551/3B

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Fig. 171: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

NOTE: This signal is used to prevent engine speed swing oscillations and tip -in shock
during clutch release and is required by the cruise control system.

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Ignition must remain switched on for this.

When indicated on display:

Fig. 172: VAG 1551 Scan Tool Display - Clutch Vacuum Vent Valve Switch, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

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z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 173: VAG 1551 Scan Tool Display - Clutch Vacuum Vent Valve Switch, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -6- and -6- to select "display group number 066" and press -Q- button to confirm input.

Indicated on display:

Fig. 174: VAG 1551 Scan Tool Display - Clutch Vacuum Vent Valve Switch, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check Clutch Pedal Position (CPP) switch in display field 2.

DISPLAY GROUP 66: SIGNALS TO ENGINE CONTROL MODULE (ECM)

Display fields
1 2 3 4
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Display group 66: Signals to Engine Control Module (ECM)

Display xxx km/h XXXX xxx km/h XXXX
Indicated ACTUAL Switch positions SPECIFIED Switch
speed speed positions
Work area X0XX X1XX
Specified X0XX
value: (with clutch pedal not operated)
X1XX
(with clutch pedal operated)
Note: Value: X = no significance (switch points
are slightly offset)

If indications do not resemble description, go to CHECK SWITCH .

Check switch

z Remove driver-side storage compartment.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Disconnect harness connector at Clutch Pedal Position (CPP) switch.

Fig. 175: Identifying Connector Terminals At Clutch Pedal Position (CPP) Switch
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminals 1 and 2 for resistance measurement.

z Specified value: approx. 0 ohm

z Depress clutch pedal.

z Specification: INFINITY ohm (no continuity)

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If specified value is not obtained:

z Check adjustment of Clutch Pedal Position (CPP) switch

or

z Replace Clutch Pedal Position (CPP) switch.

If specified value is obtained, go to CHECKING VOLTAGE SUPPLY .

Checking voltage supply

z Connect VAG1527B voltage tester as follows:

CLUTCH VACUUM VENT VALVE SWITCH CIRCUIT TEST - VOLTAGE SUPPLY

Harness connector terminal Measure to
1 Chassis Ground

Fig. 176: Identifying Clutch Vacuum Vent Valve Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z LED must light.

If LED does not light:

z Check wire connection from terminal 1 of connector to Fuel Pump (FP) relay via fuse for open circuit and
short circuit to Ground.

See appropriate System Wiring Diagrams article.

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If LED lights, go to CHECKING ACTIVATION .

Checking activation

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

Fig. 177: Identifying Clutch Vacuum Vent Valve Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connection for open circuit and short circuit to Ground and B+:

CLUTCH VACUUM VENT VALVE SWITCH CIRCUIT TEST - ACTIVATION

Harness connector terminal VAG1598/31 test box socket
2 39

z Repair open circuit or short circuit if necessary.

Pressure switch/power steering -F88-, checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1

or

z VAG1551 with VAG1551/3B

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Fig. 178: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

The pressure switch for power steering is used for idle stabilization when steering is turned to full stop (left or
right).

Test sequence

z Connect VAS5051 tester or VAG1551 scan tool and select control module for engine electronics using
"address word" 01. See VAS5051 VEHICLE DIAGNOSTIC, TESTING AND INFORMATION
SYSTEM OR VAG1551 SCAN TOOL, CONNECTING AND SELECTING FUNCTIONS .

Engine must run at idle for this.

When indicated on display:

Fig. 179: VAG 1551 Scan Tool Display - Pressure Switch/Power Steering, Checking (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.
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z Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.

When indicated on display:

Fig. 180: VAG 1551 Scan Tool Display - Pressure Switch/Power Steering, Checking (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Press buttons -0-, -5- and -6- to select "display group number 056" and press -Q- button to confirm input.

Indicated on display:

Fig. 181: VAG 1551 Scan Tool Display - Pressure Switch/Power Steering, Checking (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check pressure switch/power steering in display field 4.

DISPLAY GROUP 56: IDLE STABILIZATION WITH ENGINE AT IDLE AND OPERATING
TEMPERATURE
Display fields
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1 2 3 4
Display group 56: Idle stabilization with engine at idle and operating temperature
Display xxx /min xxx /min x.x % XXXXX
Indicated Engine speed Engine speed Idle control Operating conditions
(actual) (specified) torque change
Work area 0XXXX
1XXXX
Specified 0XXXX
value: (with steering wheel straight
ahead or turned slightly)
1XXXX (with steering wheel at
full stop)
Note: Value: X = no significance

If indications do not resemble description, go to CHECK SWITCH .

Check switch

z Disconnect harness connector at pressure switch/power steering -F88 -, at power steering pump.

Fig. 182: Identifying Power Steering Pump Pressure Switch

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter at switch for resistance measurement.

z Start engine.
z Specification: INFINITY ohm (no continuity)

z Turn steering as far to right or left as possible.

z Specified value: approx. 0 ohm

If indication does not change:

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z Replace pressure switch/power steering -F88 -.

If indication changes:

z See CHECKING WIRE CONNECTIONS .

Checking wire connections

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .

Fig. 183: Identifying Power Steering Pump Pressure Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check the following wire connections for open circuit and short circuit to Ground and B+:

POWER STEERING PUMP PRESSURE SWITCH CIRCUIT TEST - OPENS/SHORTS

Harness connector terminal VAG1598/31 test box socket
1 49
2 50

z Repair open circuit or short circuit if necessary.

Wiring for fuel level signal, checking

NOTE: z The Engine Control Module (ECM) receives the fuel level signal from the
instrument cluster.
z The processed signal enters at terminal 30 of the ECM and is used to
determine the cause of certain recognized malfunctions (for example,
combustion misfires).

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z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
z Check wire connection from terminal 30 at test box to instrument cluster for open circuit and short circuit
to B+/Ground.

Data exchange, Motronic / ABS (CAN-bus), checking

Special tools and equipment

z VAG1526A
z VAG1594A
z VAG1598/31
z VAS5051 with VAG5051/1
{ or

z VAG1551 with VAG1551/3B

Fig. 184: Identifying Special Tools And Equipment

Courtesy of AUDI OF AMERICA, INC.

Checking

z Check DTC memory of ABS control module (w/EDL).

If there is a DTC related to the CAN -bus/databus power train stored:

z Connect VAG1598/31 test box at wiring harness to ECM, do not connect ECM. See WIRE AND
COMPONENT TEST USING VAG1598/31 TEST BOX .
z Check the following wire connections for open circuit and short circuit to Ground and B+:

ABS CONTROL MODULE (W/EDL) -J104 - OR DATA-BUS CAPABLE SYSTEMS

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TERMINALS SPECIFICATION
Test box VAG1598/31 ABS control module (w/EDL) -J104 - or DATA-bus capable systems
socket Terminals
58 See appropriate System Wiring Diagrams article.
60
77
79

z Repair open circuit or short circuit if necessary.

If wire connection is OK:

z Replace ABS control module or Engine Control Module (ECM) as a test.

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2000-2004 ENGINE PERFORMANCE

Multiport Fuel Injection, 1.8L Turbo, AWP - TT

MULTIPORT FUEL INJECTION

INJECTION SYSTEM, SERVICING

Safety precautions

To prevent injuries to persons and/or damage to the fuel injection and ignition system, note the following
points:

z Always switch off the ignition before connecting or disconnecting injection or ignition system wiring or
tester cables.
z In order to run the engine at starting speed without actually starting it (for example, to test compression),
unplug the connectors on the ignition coils and also the connectors on the injectors.
z During some of the tests the control module may identify and store a fault. The Diagnostic Trouble Code
(DTC) memory should therefore be checked and (if necessary) erased after completing the tests and any
repair work that may be required. The readiness code must be generated after erasing the Diagnostic
Trouble Code (DTC) memory. See GENERATE READINESS CODE .
z Always switch off the ignition before cleaning the engine.
z Always switch off the ignition before connecting or disconnecting the battery, otherwise the engine
control module may be damaged.

Note the following points if test equipment is used during a road test:

WARNING: z To avoid any risk of accident, observe the following precautions

when using test instruments while road testing the vehicle:

Audi TT Coupe:

z Use only VAS 5051 or V.A.G 1551 to read measured value blocks.
The tester must always be secured on the rear seat and operated
from the rear seat by a second person.
z Due to the limited space, slide the front passenger's seat forward as
far as it will go and (without pulling the release lever) incline the
backrest as far forward as possible by turning the adjuster knob. Do
not operate the release lever to tilt the backrest forward.

Audi TT Roadster:

z In the Audi TT Roadster, use only V.A.G 1552 and with the front
passenger's airbag switched off.

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z Switch off the front passenger's airbag by means of the key-

operated switch in the glove box.
z Switch on front passenger's airbag after testing has been
completed.

WARNING: Fuel system is under pressure. Before opening the system place a cloth
around the connection. Then release pressure by carefully loosening the
connection.

Rules of cleanliness

When working on the fuel supply/injection system, pay careful attention to the following 6 rules for ensuring
maximum cleanliness:

z Thoroughly clean all unions and the adjacent areas before disconnecting.
z Place parts that have been removed on a clean surface and cover them over. Do not use fluffy cloths.
z Carefully cover over or seal opened components if the repair cannot be completed immediately.
z Only install clean components:

Only unpack replacement parts immediately prior to installation.

Do not use parts that have been stored loose (e.g. in tool boxes etc.).

z When the system is open:

Do not work with compressed air if this can be avoided.

Do not move vehicle unless absolutely necessary.

z Electrical connectors:

Protect against dirt and moisture when disconnected.

Make sure they are dry before re - connecting.

Technical data

TECHNICAL DATA
Engine code letters AWP (1.8L/5V/132 kW engine)
Idling speed 700 to 820 RPM
Not adjustable - controlled by idling speed stabilization
Engine speed limitation approx. 6800 RPM
Controlled by switching off the injectors
Fuel pressure at idling speed Vacuum hose connected approx. 2.5 bar
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Vacuum hose disconnected approx. 3.0 bar

Holding pressure after 10 minutes at least 1.5 bar
Injectors Spray pattern Two-hole nozzle (same on all injectors)
Injection qty. (30 s) 145 +/- 12 ml
Resistance (room temperature) 12 to 13ohm

Component locations overview

The following list pertains to Fig. 1 .

1. - Leak Detection Pump (LDP) - V144-

z Under wheelhousing liner at front right

z Checking:

See LEAK DETECTION PUMP (LDP)-V144-, CHECKING .

2. - Heated Oxygen Sensor (HO2S)-G39- with Oxygen Sensor (O2S) Heater -Z19-
z Constantly operating oxygen sensor

z Installation location of oxygen sensors and connector cover, see INSTALLATION LOCATION
OF OXYGEN SENSORS AND CONNECTOR COVER .
z Color coding of oxygen sensor connectors, see COLOR CODING OF OXYGEN SENSOR
CONNECTORS .
z Checking oxygen sensor and oxygen sensor control before catalytic converter, see OXYGEN
SENSOR CONTROL, TESTING .
z Testing oxygen sensor ageing on oxygen sensor (before catalytic converter), see OXYGEN
SENSOR AGING (BEFORE CATALYTIC CONVERTER) TESTING .
z Checking oxygen sensor heating before catalytic converter, see OXYGEN SENSOR (O2S)
HEATER - Z19- (BEFORE CATALYTIC CONVERTER), TESTING .
z Removing and installing, see OXYGEN SENSOR, REMOVING AND INSTALLING

2 - Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- with Oxygen
Sensor (O2S) Heater 1 -Z29 -
z Installation location of oxygen sensors and connector cover, see INSTALLATION LOCATION
OF OXYGEN SENSORS AND CONNECTOR COVER .
z Color coding of oxygen sensor connectors, see COLOR CODING OF OXYGEN SENSOR
CONNECTORS .
z Checking oxygen sensor and oxygen sensor control after catalytic converter, see OXYGEN
SENSOR AND OXYGEN SENSOR CONTROL (AFTER CATALYTIC CONVERTER),
TESTING .
z Testing oxygen sensor heating for oxygen sensor (after catalytic converter), see OXYGEN
SENSOR (O2S) HEATER 1 -Z29- (AFTER CATALYTIC CONVERTER), TESTING .
z Removing and installing, see OXYGEN SENSOR, REMOVING AND INSTALLING .

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3 - Camshaft Position (CMP) sensor -G40-

z Checking, see CAMSHAFT POSITION (CMP) SENSOR -G40-, TESTING

4 - Injectors
z Cylinder 1 Fuel Injector - N30-

z Cylinder 2 Fuel Injector - N31-

z Cylinder 3 Fuel Injector - N32-

z Cylinder 4 Fuel Injector - N33-

z Testing, see FUEL INJECTORS, TESTING

z Removing and installing, see FUEL INJECTORS, REMOVING AND INSTALLING

5 - Motronic Engine Control Module (ECM) -J220-

z Testing voltage supply of engine control module, see VOLTAGE SUPPLY FOR CONTROL
MODULE, TESTING .
z See PROCEDURE AFTER VOLTAGE SUPPLY OPEN CIRCUIT .

z Replacing, see ENGINE CONTROL MODULE (ECM) (WITHOUT METAL ANTI-THEFT

HOUSING), REPLACING .
6 - Ignition coils
z Ignition Coil -N-

z Ignition Coil 2 -N128-

z Ignition Coil 3 -N158-

z Ignition Coil 4 -N163-

z Testing, see IGNITION COILS WITH POWER OUTPUT STAGES, TESTING

7 - Wastegate bypass regulator valve -N75-

z Checking:

See CHARGE AIR PRESSURE SYSTEM WITH TURBOCHARGER .

8 - Accelerator position sender - G79- and accelerator position sender 2 -G185-

z Fitting location, see INSTALLATION LOCATION OF ACCELERATOR POSITION
SENDERS -G79- AND -G185- .
z Testing, see ACCELERATOR POSITION SENSORS, TESTING .

9 - Brake light switch -F- and brake pedal position switch - F47 -
z Fitting location, see INSTALLATION LOCATION OF BRAKE LIGHT SWITCH -F- AND
BRAKE PEDAL SWITCH (CRUISE CONTROL/DIESEL DIRECT FUEL INJECTION -
F47- .
10 - Clutch vacuum vent valve switch -F36 -
z Fitting location, see INSTALLATION LOCATION OF CLUTCH VACUUM VENT VALVE
SWITCH -F36- .
11 - Instrument cluster
z With Malfunction Indicator (Lamp MIL) -K83- (exhaust emissions warning lamp). See Notes for

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MIL warning lamp in MALFUNCTION INDICATOR LAMP (MIL) -K83- IN INSTRUMENT

CLUSTER .
z With fault lamp for Electronic Power Control (EPC) warning lamp -K132-. Notes for EPC- control
lamp. See ELECTRONIC THROTTLE WARNING LAMP IN INSTRUMENT CLUSTER .
12 - Motronic Engine Control Module (ECM) power supply relay -J271-
z Installation location, see INSTALLATION LOCATION OF MOTRONIC ENGINE
CONTROL MODULE (ECM) POWER SUPPLY RELAY -J271- AND SECONDARY AIR
INJECTION (AIR) PUMP RELAY -J299-
z Testing, see MOTRONIC ENGINE CONTROL MODULE (ECM) POWER SUPPLY
RELAY -J271-, TESTING .
13 - Secondary Air Injection (AIR) pump relay -J299-
z Installation location, see INSTALLATION LOCATION OF MOTRONIC ENGINE
CONTROL MODULE (ECM) POWER SUPPLY RELAY -J271- AND SECONDARY AIR
INJECTION (AIR) PUMP RELAY -J299- .
z Checking:

See SECONDARY AIR SYSTEM, COMPONENTS AND FUNCTION .

14 - Mass Air Flow (MAF) sensor -G70-

z Testing, see MASS AIR FLOW (MAF) SENSOR - G70-, TESTING

15 - Engine Coolant Temperature (ECT) sensor -G62-

z Testing, see ENGINE COOLANT TEMPERATURE (ECT) SENSOR -G62-, TESTING .

z If necessary release pressure in cooling system before removing

16 - Valve -1- for camshaft adjustment -N205-

z Checking:

See ENGINE -- CYLINDER HEAD, VALVETRAIN .

17 - Fuel pressure regulator

z Testing, see SYSTEM PRESSURE, FUEL PRESSURE REGULATOR AND HOLDING
PRESSURE, CHECKING
18 - Engine Speed (RPM) Sensor - G28-
z Checking, see ENGINE SPEED (RPM) SENSOR - G28-, TESTING

19 - Knock Sensor (KS) 2 -G66-

20 - Recirculating valve for turbocharger -N249-
z Installation location, see INSTALLATION LOCATION OF RECIRCULATING VALVE FOR
TURBOCHARGER -N249- AND SECONDARY AIR INJECTION (AIR) SOLENOID
VALVE -N112-
z Checking:

See CHARGE AIR PRESSURE SYSTEM WITH TURBOCHARGER

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21 - 3 pin connector
z Qty. 3

z Installation location, see INSTALLATION LOCATIONS OF 3-PIN CONNECTORS

z For knock sensor 1 -G61

z For engine speed sender - G28

z For knock sensor 2 -G66

22 - Secondary Air Injection (AIR) solenoid valve -N112-

z Installation location, see INSTALLATION LOCATION OF RECIRCULATING VALVE FOR
TURBOCHARGER -N249- AND SECONDARY AIR INJECTION (AIR) SOLENOID
VALVE -N112-
z Checking:

See SECONDARY AIR SYSTEM, COMPONENTS AND FUNCTION .

23 - Knock Sensor (KS) 1 -G61-

24 - Intake Air Temperature (IAT) Sensor -G42-
z Testing, see INTAKE AIR TEMPERATURE (IAT) SENSOR -G42-, TESTING .

25 - Secondary Air Injection (AIR) pump motor -V101-

z Checking:

See SECONDARY AIR SYSTEM, COMPONENTS AND FUNCTION .

26 - Pressure switch/power steering -F88 -

z Installation location, see INSTALLATION LOCATION OF PRESSURE SWITCH/POWER
STEERING -F88-
27 - Throttle valve control module -J338 -
z With Throttle drive (power accelerator actuation) - G186 -, Angle sensor -1- for throttle drive
(power accelerator actuation) - G187 - and Angle sensor -2- for throttle drive (power accelerator
actuation) - G188 -
z Testing, see THROTTLE VALVE CONTROL MODULE -J338-, TESTING

z If replaced perform adaptation, see THROTTLE VALVE CONTROL MODULE,

ADAPTATION
28 - Evaporative Emission (EVAP) canister -N80-
z Testing, see EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR
VALVE, TESTING
29 - Charge air pressure sensor - G31-
z Screwed onto top of charge air cooler

z Checking:

See CHARGE AIR PRESSURE SYSTEM WITH TURBOCHARGER .

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Fig. 1: Identifying Fuel Injection System Components

Courtesy of AUDI OF AMERICA, INC.

Installation location of recirculating valve for turbocharger -N249- and Secondary Air Injection (AIR) solenoid valve -N112-

z Installation location: under metal bracket at front of intake manifold

1. - Secondary Air Injection (AIR) Solenoid Valve -N112-

2. - Non-return valve
3. - To vacuum reservoir
4. - To mechanical air recirculation valve
5. - To combination valve of secondary air system
6. - To connection on intake manifold
7. - Recirculating valve for turbocharger -N249-

Fig. 2: Locating Secondary Air Injection (Air) Solenoid Valve -N112-

Courtesy of AUDI OF AMERICA, INC.
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Installation location of accelerator position senders -G79- and -G185-

Fig. 3: Locating Accelerator Position Senders -G79- And -G185-

Courtesy of AUDI OF AMERICA, INC.

Installation location of oxygen sensors and connector cover

1. - Heated oxygen sensor (HO2S) -G39- and oxygen sensor (O2S) heater -Z19-
2. - Connector cover
3. - Oxygen Sensor (O2S) behind three way catalytic converter (TWC)-G130- with oxygen sensor (O2S)
heater 1 -Z29 -

The connectors for oxygen sensors and oxygen sensor heaters are accessible after unscrewing the connector
cover from the underside of the vehicle (right side) -arrows-

Fig. 4: Locating HO2S Connector Cover

Courtesy of AUDI OF AMERICA, INC.

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Color coding of oxygen sensor connectors

Black connector Heated oxygen sensor (HO2S) -G39- and oxygen sensor (O2S) heater -Z19-

Brown connector Oxygen Sensor (O2S) behind three way catalytic converter (TWC) -G130- with oxygen
sensor (O2S) heater 1 -Z29 -

Fig. 5: Locating Oxygen Sensor Connectors

Courtesy of AUDI OF AMERICA, INC.

Installation locations of 3-pin connectors

1. - For knock sensor (KS) 1 -G61-

2. - For engine speed (RPM) sensor -G28-
3. - For knock sensor (KS) 2 -G66-

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Fig. 6: Locating 3-Pin Electrical Connectors

Courtesy of AUDI OF AMERICA, INC.

Installation location of brake light switch -F- and brake pedal switch (cruise control/diesel direct fuel injection -F47-

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Fig. 7: Locating Brake Light Switch

Courtesy of AUDI OF AMERICA, INC.

Installation location of clutch vacuum vent valve switch -F36-

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Fig. 8: Locating Clutch Vacuum Vent Valve Switch -F36-

Courtesy of AUDI OF AMERICA, INC.

Installation location of pressure switch/power steering -F88-

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Fig. 9: Locating Pressure Switch/Power Steering -F88

Courtesy of AUDI OF AMERICA, INC.

Installation location of Motronic Engine Control Module (ECM) Power Supply Relay -J271- and Secondary Air Injection (AIR)
Pump Relay -J299-

z Under cover on bulkhead (left side)

1. - Motronic Engine Control Module (ECM) Power Supply Relay-J271-

2. - Secondary Air Injection (AIR) Pump Relay -J299-

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Fig. 10: Locating ECM Power Supply Relay - J271- & Secondary Air Injection Pump Relay -J299-
Courtesy of AUDI OF AMERICA, INC.

NOTE: To remove protective cover on vehicles with suspension turret stiffener strut,
disengage and move down relay carrier on bulkhead. If necessary, also unplug
connector on mass air flow sensor.

Air cleaner, disassembling and assembling

The following list pertains to Fig. 11 .

1. - Hex bolt - 10 Nm
2. - Air cleaner lower part
3. - Hose
z To secondary air pump

4. - Seal
5. - Mass Air Flow (MAF) Sensor- G70-
6. - Phillips-head screw
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7. - Air ducting
8. - 5 pin connector
9. - Phillips-head screw
10. - Cover
11. - Retaining clip
12. - Air cleaner upper part
13. - Filter element
14. - Nut - 10 Nm
15. - Bush
16. - Rubber grommet
17. - Air intake connection

Fig. 11: Exploded View Of Air Cleaner Assembly

Courtesy of AUDI OF AMERICA, INC.

Wiring and component check using test box VAG 1598/31

NOTE: z If the Engine Control Module (ECM) is equipped with a metal anti -theft
housing (for theft prevention), the metal anti-theft housing must be
removed from the ECM to connect the test box. Procedure, see ENGINE
CONTROL MODULE (ECM) (WITH METAL ANTI-THEFT HOUSING),
REPLACING . After repairs are complete, the metal anti -theft housing
must be reinstalled.
z Test box VAG 1598/31 is designed so that it can be connected to the wiring
harness for the engine control module and to the engine control module
itself at the same time.
z This has the advantage of enabling the engine management system to
remain fully operational even with the test box connected (for example,
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when testing signals while the engine is running).

z The instructions for performing the individual tests indicate whether or not
the engine control module itself also needs to be connected to the test
box.
z Always use adapter set VAG 1594A to connect test equipment (e.g. voltage
tester VAG 1527B, voltage tester VAG 1526A etc.).

WARNING: To prevent damage to the electronic components, switch to the

respective measuring range before connecting the measuring cable and
observe the test prerequisites.

Special tools and equipment

z VAG 1598/31

Fig. 12: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Work sequence

z Switch off ignition.

z Remove engine control module. See ENGINE CONTROL MODULE (ECM) (WITHOUT METAL
ANTI-THEFT HOUSING), REPLACING .
z Connect test box VAG 1598/31 to wiring harness connectors (do not connect engine control module).
Connect Ground clamp on test box to Ground -arrow-. The respective test sequences indicate whether the
engine control module itself also needs to be connected to the test box.

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Fig. 13: Connecting Test Box Vag 1598/31 To Wiring Harness Connectors
Courtesy of AUDI OF AMERICA, INC.

z Carry out test as described in the repair instructions.

NOTE: After reconnecting the engine control module the following operations must be
performed:

z Perform adaptation of throttle valve control module -J338-. See THROTTLE

VALVE CONTROL MODULE, ADAPTATION .
z Check and if necessary erase the Diagnostic Trouble Code (DTC) memory.
See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND
ERASING .
z If the Diagnostic Trouble Code (DTC) memory was erased, generate the
readiness code. See GENERATE READINESS CODE .

Procedure after voltage supply open circuit

NOTE: After re-connecting the voltage supply the following operations must be
performed:

z Perform adaptation of throttle valve control module -J338-. See THROTTLE

VALVE CONTROL MODULE, ADAPTATION .
z Check and if necessary erase the Diagnostic Trouble Code (DTC) memory.
See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND
ERASING .
z If the Diagnostic Trouble Code (DTC) memory was erased, generate the
readiness code. See GENERATE READINESS CODE .

Engine Control Module (ECM) (without metal anti-theft housing), replacing

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Removing ECMs with metal anti -theft housing. See ENGINE CONTROL MODULE (ECM) (WITH
METAL ANTI-THEFT HOUSING), REPLACING .

NOTE: When the engine control module is disconnected the learned values are erased
but the contents of the Diagnostic Trouble Code (DTC) memory remain intact.

Special tools and equipment

z VAS 5051 and VAS 5051/1

Fig. 14: Identifying Special Tool VAS 5051

Courtesy of AUDI OF AMERICA, INC.

Removing

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.

Display on VAS 5051:

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Fig. 15: Scan Tool Display - 01, Engine electronics

Courtesy of AUDI OF AMERICA, INC.

1. - Control module identification of engine control module. See WORK SEQUENCE .

2. - Control module identification of immobilizer. See WORK SEQUENCE .

z Always start by calling up and printing out the control module identification.
z Check the coding against the list of coding variants. See CODING TABLE .
z Switch off ignition.
z Pry off cover caps (2x) on wiper arms with a screwdriver.
z Loosen hex nuts -arrows- several turns. See Fig. 16 .
z Loosen wiper arms -1- by moving them gently on the wiper shafts. See Fig. 16 .
z Remove hex nuts completely and take off wiper arms.
z Remove rubber seal -2- from plenum chamber cover. See Fig. 16 .
z Detach cover from plenum chamber -3- and move clear toward windscreen.

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Fig. 16: Detaching Cover From Plenum Chamber

Courtesy of AUDI OF AMERICA, INC.

z Release retainer catches on connectors -arrow- and unplug connectors from control module.

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Fig. 17: Locating Connectors Control Module

Courtesy of AUDI OF AMERICA, INC.

Installing

Install in reverse sequence; note the following points:

z Bend back retainer on bracket.

NOTE: After installing the new engine control module the following operations must be
performed:

z Check and if necessary erase the Diagnostic Trouble Code (DTC) memory. See DIAGNOSTIC
TROUBLE CODE (DTC) MEMORY, CHECKING AND ERASING .
z Perform adaptation of throttle valve control module -J338-. See THROTTLE VALVE CONTROL
MODULE, ADAPTATION .
z Check the notes on coding new engine control modules. See CODE CONTROL MODULE
(FUNCTION 07) .
z On vehicles with cruise control (identifiable by controls on steering column), activate the cruise control
via the engine control module.

See CRUISE CONTROL SYSTEM, ACTIVATING/DEACTIVATING .

z Perform adaptation of immobilizer to engine control module.

See ANTI-THEFT IMMOBILIZER FROM 09.00, ON BOARD DIAGNOSTIC (OBD) .

z Generate the readiness code. See GENERATE READINESS CODE .

Engine Control Module (ECM) (with metal anti-theft housing), replacing

Removing ECMs without metal anti-theft housing, see ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

NOTE: Adaptation values are erased when the harness connector is disconnected from
the Engine Control Module (ECM), the DTC memory content remains intact.

Remove Engine Control Module (ECM)

Removing

z Connect VAS5051 tester and select vehicle system "01 - Engine Electronics". Ignition must be switched
on for this.

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Fig. 18: Scan Tool Display - 01-Engine Electronics

Courtesy of AUDI OF AMERICA, INC.

VAS5051 tester display will indicate the control module identification and coding -2-.

z Always allow display of control module identification first and print it out.
z Switch ignition off.
z Pry off both caps at wiper arms using a screwdriver.
z Loosen hex -nuts (arrows) several turns. See Fig. 19 .
z Loosen wiper arms -1- from wiper axle by lightly tilting. See Fig. 19 .
z Remove hex nuts completely and remove wiper arms.
z Remove plenum chamber cover rubber seal -2-. See Fig. 19 .
z Remove plenum chamber cover -3- and place it on windshield side.

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Fig. 19: Removing Plenum Chamber Cover

Courtesy of AUDI OF AMERICA, INC.

NOTE: Item -1- in illustration shows the Engine Control Module (ECM) with anti-theft
housing.

z Use a screwdriver to press locking lug of bracket (arrow) to the side and then remove Engine Control
Module (ECM) toward front.

Fig. 20: Pressing Locking Lug Of Bracket

Courtesy of AUDI OF AMERICA, INC.

To restrict accessibility (for theft prevention) to the harness connectors and Engine Control Module (ECM), the
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Engine Control Module (ECM) -1- is screwed to a metal anti-theft housing -4- via a locking mechanism -2- and
snap-off screws -3-.

Fig. 21: Identifying Engine Control Module With Metal Anti-Theft Housing
Courtesy of AUDI OF AMERICA, INC.

The threads of the snap -off screws are coated with locking compound to make it more difficult to remove the
snap -off screws.

To disconnect the harness connectors from the Engine Control Module (ECM) (e.g. when connecting a test box
or when replacing the ECM), the ECM must be removed from the metal anti-theft housing. This procedure is
described as follows.

The following equipment is required:

Fig. 22: Identifying Wiring Harness Repair Kit

Courtesy of AUDI OF AMERICA, INC.
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z Heat gun -1- (from VAS1978 Wiring Harness Repair Kit)

z Adapter nozzle -2- (also from VAS1978 Wiring Harness Repair Kit)
z Standard locking pliers

Procedure:

WARNING: The following work steps must be adhered to exactly to avoid damage
(burning) of wires, harness connectors, insulation and control modules!
Observe operating instructions of heat gun.

Fig. 23: Identifying Engine Control Module With Metal Anti-Theft Housing
Courtesy of AUDI OF AMERICA, INC.

z "Flip" the Engine Control Module (ECM) with anti -theft housing in direction of the engine compartment
so that the locking mechanism (item -2- in illustration) becomes visible and place a clean rag below the
Engine Control Module (ECM) with anti -theft housing.
z Adjust the heat gun as shown in illustration, i.e. temperature adjustment -2- to maximum heat output and
the two -stage switch for air mass -3- to position 3.

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Fig. 24: Adjusting The Heat Gun

Courtesy of AUDI OF AMERICA, INC.

NOTE: Next, use the heat gun to heat the threads of the locking mechanism in which
the snap -off screws are screwed into. This step loosens the locking compound
on the threads of the snap-off screws for easier removal.

WARNING: By heating the locking mechanism threads, the snap - off screws and
parts of the metal anti -theft housing will also become very hot. Be careful
not to get burned! If possible, make sure that only the threads are in the
vicinity of becoming heated. If necessary, cover them.

z Guide nozzle -1- of heat gun to the locking mechanism threads so that the nozzle "encloses" the threads.
It is OK to let the nozzle make contact at the upper end of the metal anti -theft housing.

Fig. 25: Guiding Nozzle Of Heat Gun To The Locking Mechanism Threads
Courtesy of AUDI OF AMERICA, INC.
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z Switch on heat gun and heat up thread for approx. 20 to 25 seconds.

z Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of
arrow.

Fig. 26: Removing Snap-Off Screw

Courtesy of AUDI OF AMERICA, INC.

The procedure for the second snap-off screw is exactly the same. Be very careful since the control module
connector is in close proximity.

z Guide nozzle -1- of the heat gun to the locking mechanism threads again so that the nozzle "encloses" the
threads. It is OK to let the nozzle make contact at the upper end of the metal anti -theft housing.

Fig. 27: Guiding Nozzle Of Heat Gun To The Locking Mechanism Threads
Courtesy of AUDI OF AMERICA, INC.

z Switch on heat gun and heat up threads for approx. 20 to 25 seconds.

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z Next, using locking pliers -1-, grab screw head -2- and remove snap-off screw by turning in direction of
arrow.

Fig. 28: Removing Snap-Off Screw

Courtesy of AUDI OF AMERICA, INC.

The Engine Control Module (ECM) can now be removed from the metal anti-theft housing.

z Disengage connectors from Engine Control Module (ECM) and then disconnect connectors.
z Remove old Engine Control Module (ECM) and insert new one.

Installing Engine Control Module (ECM)

Installation is the reverse order of removal, noting the following:

After repairs are complete, the metal anti -theft housing must be reinstalled. Use new snap-off screws.

z Bend back locking lug of bracket.

After installing a new Engine Control Module (ECM), the following work steps must be performed:

z Activate Engine Control Module (ECM) in "Guided Troubleshooting" below subject heading "Engine
Control Module (ECM), replacing".

Use VAS5051 tester to do so.

Idle speed, testing

Special tools and equipment

z VAS 5051 and VAS 5051/1

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Fig. 29: Identifying Special Tool VAS 5051

Courtesy of AUDI OF AMERICA, INC.

Requirements for test:

z Exhaust system free of leaks

z Coolant temperature at least 80 °C
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z Electrical consumers switched off (radiator fan must not run during the test)
z Air conditioner switched off
z No pressure gauge connected

NOTE: z The idling speed cannot be adjusted.

z The idling speed is tested during the basic setting of the engine.
z During the basic setting of the engine, the solenoid valve for the
evaporative emissions (EVAP) canister purge regulator valve -N80 is
closed and the air conditioner compressor is automatically switched off.

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.
z Check Diagnostic Trouble Code (DTC) memory. See DIAGNOSTIC TROUBLE CODE (DTC)
MEMORY, CHECKING AND ERASING . The Diagnostic Trouble Code (DTC) memory must be
clear. If necessary, correct any faults and erase the Diagnostic Trouble Code (DTC) memory. Switch off
the engine, then start up again. Take vehicle for a test drive and check the Diagnostic Trouble Code
(DTC) memory again to make sure it is clear.
z Run the engine at idling speed.

WARNING: The electric radiator fan should not be running.

Display on VAS 5051:

Fig. 30: Scan Tool Display - Idle Speed, Testing (1 Of 4)

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Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "04 - Basic settings" from the menu -1-.

Display on VAS 5051:

Fig. 31: Scan Tool Display - Idle Speed, Testing (2 Of 4)

Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

2. Using the keypad -2-, enter "056" to select Display group 056 and confirm entry with Q button.

Display on VAS 5051:

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Fig. 32: Scan Tool Display - Idle Speed, Testing (3 Of 4)

Courtesy of AUDI OF AMERICA, INC.

z Check whether the engine speed shown in display zone -1- (actual engine speed) is within the specified
tolerance range.

DISPLAY GROUP 056: IDLING SPEED STABILIZATION WITH ENGINE IDLING AT

NORMAL OPERATING TEMPERATURE
Display zones
1 2 3 4
Display group 056: Idling speed stabilization with engine idling at normal operating temperature
Display xxx RPM xxx RPM x.x % XXXXX
Indicates Engine speed (actual) Engine Idling Operating status
speed speed
(specified) control -
torque
change
Specification 700 to 820 RPM 760 RPM x.x % 00000
Note If readout does not match Relevance of figures,
specification, seeRELEVANCE OF
seeRELEVANCE OF FIGURES IN 5-DIGIT
FIGURES IN 5-DIGIT READOUT FOR DISPLAY
READOUT FOR DISPLAY GROUP 056
GROUP 056

NOTE: z The value shown in display zone 1 is the actual engine speed.
z The value shown in display zone 2 (specified engine speed) is a theoretical
value calculated by the engine control module.
z When the engine is idling the engine control module tries constantly to
adjust the actual engine speed so that it matches the specified value.
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z This means that the actual engine speed when idling should always be
approximately the same as the specified engine speed.
z Display zones 3 and 4 provide additional information which is not relevant
when checking the idling speed.

Display on VAS 5051:

Fig. 33: Scan Tool Display - Idle Speed, Testing (4 Of 4)

Courtesy of AUDI OF AMERICA, INC.

If the specification is obtained:

z Press the <- button to exit from diagnosis function "04 - Basic settings".

If the specification is not attained:

z Check Diagnostic Trouble Code (DTC) memory again. See DIAGNOSTIC TROUBLE CODE (DTC)
MEMORY, CHECKING AND ERASING .
z If the Diagnostic Trouble Code (DTC) memory was erased the readiness code must be generated again.
See GENERATE READINESS CODE .

If the idling speed is too high or too low and there are no faults recorded in the Diagnostic Trouble Code
(DTC) memory, carry out the following tests (marked with dots):

z Test for unmetered air in the intake system. See INTAKE AIR SYSTEM, CHECKING FOR LEAKS
(UNMETERED AIR) .
z Test throttle valve control module. See THROTTLE VALVE CONTROL MODULE -J338-,
TESTING .
z EVAP canister purge regulator valve constantly open. Testing, see EVAPORATIVE EMISSION
(EVAP) CANISTER PURGE REGULATOR VALVE, TESTING .
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z Perform adaption of throttle valve control module. See THROTTLE VALVE CONTROL MODULE,
ADAPTATION .

Relevance of figures in 5-digit readout for Display Group 056

RELEVANCE OF FIGURES IN 5-DIGIT READOUT FOR DISPLAY GROUP 056

xxxxx Display zone 4
0 Air conditioner compressor: 0 = air conditioner compressor off; 1 = air conditioner compressor
on
0 Display always reads "0"
0 A/C readiness maximum heater or cooling performance
0 Display always reads "0"
0 Steering assistance pressure
0 = no signal from power steering pressure switch
0 1 = Signal from power steering pressure switch (steering in turned to full lock position, fast
steering movement)

System pressure, fuel pressure regulator and holding pressure, checking

Special tools and equipment

z VAG 1318

Fig. 34: Identifying Special Tool VAG 1318

Courtesy of AUDI OF AMERICA, INC.

z VAG 1318/7
z VAG 1318/17 (2x)

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Fig. 35: Identifying Special Tool VAG 1318/7

Courtesy of AUDI OF AMERICA, INC.

NOTE: The fuel pressure regulator regulates the fuel pressure according to the intake
manifold pressure. This ensures that the drop in pressure at the injectors
remains the same throughout all engine speed and engine load ranges.

Requirements for test:

z Fuel pump relay OK. Testing, see FUEL PUMP (FP) RELAY -J17-, TESTING AND
ACTIVATING .
z Fuel pump OK. Testing:

See FUEL PUMP, ELECTRICAL TESTING .

z Fuel filter OK
z Battery voltage not less than 12.7 V

WARNING: Fuel system is under pressure. Before opening the system place a cloth
around the connection. Then release pressure by carefully loosening the
connection.

Testing system pressure

z Remove engine cover panel -1- -arrows-.

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Fig. 36: Removing Engine Cover Panel

Courtesy of AUDI OF AMERICA, INC.

z Briefly open fuel tank filler cap (to release pressure).

z Press release catch and disconnect fuel supply pipe -1-.

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Fig. 37: Disconnecting Fuel Supply Pipe

Courtesy of AUDI OF AMERICA, INC.

z Connect pressure gauge VAG 1318 to fuel supply pipe using adapters 1318/7 and 1318/17 (x 2).
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z Open cut -off valve on pressure gauge (valve handle points in direction of flow).
z Start the engine and run at idling speed.
z Measure fuel pressure.

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Fig. 38: Measuring Fuel Pressure

Courtesy of AUDI OF AMERICA, INC.

z Specification: approx. 2.5 bar

z Disconnect vacuum hose from fuel pressure regulator.
z The fuel pressure should rise to approx. 3.0 bar.

Fig. 39: Disconnecting Vacuum Hose From Fuel Pressure Regulator

Courtesy of AUDI OF AMERICA, INC.

z Switch off ignition.

z Check leak -tightness and holding pressure by watching the drop in pressure on the pressure gauge.
z After 10 minutes there should still be a pressure of at least 1.5 bar.

If the holding pressure drops below 1.5 bar:

z Start the engine and run at idling speed.

z Allow pressure to build up, then switch off ignition and at the same time close cut-off valve on pressure
gauge VAG 1318 (valve handle at right angles to direction of flow -arrow-).

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Fig. 40: Closing Cut-Off Valve On Pressure Gauge VAG 1318

Courtesy of AUDI OF AMERICA, INC.

z Observe pressure drop on gauge.

If the pressure does not drop:

z Check fuel pump non -return valve.

If the pressure drops again:

z Open cut -off valve on pressure gauge VAG 1318 (valve handle points in direction of flow).
z Start the engine and run at idling speed.
z Allow the pressure to build up, then switch off the ignition. At the same time pinch the return hose (with
blue marking) firmly together.

If the pressure does not drop:

z Replace fuel pressure regulator.

If the pressure drops again:

z Check pipe connections, O-rings on fuel manifold and injectors for leaks.
z Check pressure gauge for leaks.

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NOTE: Before removing the pressure gauge, release the fuel pressure by opening the
cut -off valve. When doing this, hold a container over the connection.

Fuel injectors, testing

Special tools and equipment

z VAG 1526 A
z VAG 1527 B
z VAG 1594 A
z VAG 1598/31

Fig. 41: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Testing internal resistance

z Remove engine cover panel -1- -arrows-.

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Fig. 42: Removing Engine Cover Panel

Courtesy of AUDI OF AMERICA, INC.

z Unplug connector from injector to be tested.

z Connect multimeter to valve (resistance measurement range)
z Specification: 12 to 13 ohm (at room temperature)

Fig. 43: Measuring Fuel Injector Resistance

Courtesy of AUDI OF AMERICA, INC.

If the specification is not attained:

z Replace the injector.

If the specification is obtained, go to CHECKING VOLTAGE SUPPLY .

Checking voltage supply

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Requirements for test:

z Fuse for injectors OK.

See appropriate System Wiring Diagrams article.

z Fuel pump relay OK. Testing, see FUEL PUMP (FP) RELAY -J17-, TESTING AND
ACTIVATING .

z Unplug connector from injector to be tested.

Fig. 44: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect VAG 1527 B voltage tester as follows:

FUEL INJECTOR CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Measure against
1 Engine Ground

z Switch on ignition.
z The LED should light up.

If the LED does not light up:

z Test for open circuit in wiring between contact 1 and fuse for injectors:

See appropriate System Wiring Diagrams article.

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z Correct any open circuits.

If the LED lights up, go to TESTING ACTIVATION .

Testing activation

Test requirement:

z Internal resistance of injector OK.

z Slide back rubber sleeve on connector for injector but do not unplug the connector.
z Connect VAG 1527 B voltage tester between contact 2 (signal) and contact 1 (positive).

Fig. 45: Connecting VAG 1527B Voltage Tester Between Contact 2 (Signal) And Contact 1
Courtesy of AUDI OF AMERICA, INC.

z Operate the starter briefly. (The engine can be allowed to start.)

z The LED should flash.

NOTE: The LEDs on voltage testers with a low current draw continue to glow faintly
between impulses from the engine control module (rather than going out
completely) and become much brighter when receiving an impulse.

If the LED does not flash:

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z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself, see WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .

Fig. 46: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Test for open circuit and short to positive or Ground in the following wiring connections:

FUEL INJECTOR CIRCUIT TEST - ACTIVATION

Cylinder Connector for injector Contact Test box VAG 1598/31 Socket
1 2 96
2 2 89
3 2 97
4 2 88

z Correct short circuit or open circuit if necessary.

If the wiring is OK:

z Install a new engine control module. See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

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Fuel rail with injectors, disassembling and assembling

The following list pertains to Fig. 47 .

1. - Insert for injector - 3 Nm

z Install with locking fluid D 000 600 A2

2. - O ring
z Removing and installing, see FUEL INJECTORS, REMOVING AND INSTALLING

z Replace

z Lubricate with clean engine oil

3. - Injectors
z Cylinder 1 Fuel Injector - N30-

z Cylinder 2 Fuel Injector - N31-

z Cylinder 3 Fuel Injector - N32-

z Cylinder 4 Fuel Injector - N33-

z Removing and installing, see FUEL INJECTORS, REMOVING AND INSTALLING

4. - Supply hose
5. - Return hose
6. - Fuel rail
7. - Hex socket head bolt, -10 Nm
8. - Connector
z For injectors

z Qty. 4

9. - Fuel pressure regulator

10. - O ring
z Always replace

11. - O ring
z Always replace

12. - Retaining clip

13. - O ring
z Removing and installing, see FUEL INJECTORS, REMOVING AND INSTALLING

z Always replace

z Lubricate with clean engine oil

14. - Retaining clip

z Make sure seated correctly at injector and fuel rail

15. - Intake manifold

z With throttle valve control module -J338-

z With Intake Air Temperature (IAT) Sensor -G42-

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z Removing:

See INTAKE MANIFOLD, REMOVING AND INSTALLING .

Fig. 47: Exploded View Of Intake Manifold And Fuel Rail With Injectors
Courtesy of AUDI OF AMERICA, INC.

Fuel injectors, removing and installing

z Remove engine cover panel -1- -arrows-.

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Fig. 48: Removing Engine Cover Panel

Courtesy of AUDI OF AMERICA, INC.

z Disconnect wiring and unplug connectors for the following components:

z Intake air temperature (IAT) sensor -G42-
z camshaft position (CMP) sensor -G40-
z Throttle valve control module -J338-

WARNING: Fuel system is under pressure. Before opening the system place a cloth
around the connection. Then release pressure by carefully loosening the
connection.

z Press release catches and disconnect fuel supply line -1- and fuel return line -2.

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Fig. 49: Disconnecting Fuel Supply And Return Lines

Courtesy of AUDI OF AMERICA, INC.

z Disconnect vacuum hose from fuel pressure regulator -arrow-.

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Fig. 50: Disconnecting Vacuum Hose From Fuel Pressure Regulator

Courtesy of AUDI OF AMERICA, INC.

z Unplug connectors -1-. See Fig. 51 .

z Disengage wiring duct -2-. See Fig. 51 .
z Remove the 2 hex socket head bolts -arrows- securing the fuel rail.

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Fig. 51: Removing Fuel Rail

Courtesy of AUDI OF AMERICA, INC.

z Pull fuel rail together with injectors off intake manifold (pull off evenly from the top) and place it on a
clean cloth in the engine compartment.
z Take off retaining clip and remove injector.

NOTE: To install a new fuel rail, first disconnect the fuel hoses.

Installing

Installation is carried out in the reverse order. When doing this, note the following:

z Replace the O-rings at all opened connections. (When replacing the front O - ring, make sure not to
remove the plastic cap from the injector head. The O-ring must be pulled off over the plastic cap.)
z Moisten the O-rings with clean engine oil.
z Make sure that the injectors are installed in the correct positions.
z Check to make sure that the retainer clamps are properly seated.
z Position fuel rail together with injectors (properly secured) against intake manifold and press into place
evenly all round.

Tightening torque

TIGHTENING TORQUE: FUEL RAIL

Component Nm
Fuel rail to intake manifold 10

Fuel injector leakage, injection quantity and spray pattern, checking

Special tools and equipment

z VAG 1348/3A
z VAG 1594 A
z VAG 1598/31
z VAG 1602

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Fig. 52: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Test requirement:

z Fuel pressure OK. Testing, see SYSTEM PRESSURE, FUEL PRESSURE REGULATOR AND
HOLDING PRESSURE, CHECKING .

Test sequence

z Remove fuel rail (together with injectors) from intake manifold. See FUEL INJECTORS, REMOVING
AND INSTALLING . Do not disconnect the fuel hoses.
z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .

Testing for leaks

z Bridge contacts 1 and 65 on the test box using test leads from adapter set VAG 1594 A.
z Switch on ignition.
z The fuel pump should run.

z Check injectors for leaks (visual check). When the fuel pump is running, only 1 or 2 drops should escape
per minute from each injector.
z If a greater amount of fuel escapes, switch off the fuel pump (switch off ignition) and replace the faulty
injector. See FUEL INJECTORS, REMOVING AND INSTALLING .

Checking injection quantity

z Place the injector which is to be tested into a measuring glass from injection quantity tester VAG 1602.
z Connect one of the injector contacts to engine Ground using test lead and crocodile clamp from VAG
1594 A.
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z Connect second injector contact to positive using remote control VAG 1348/3 A, adapter cable VAG
1348/3 -2 and auxiliary cable.

Fig. 53: Connect Second Injector Contact To Positive Using Remote Control VAG 1348/3 A
Courtesy of AUDI OF AMERICA, INC.

z Bridge contacts 1 and 65 on the test box using test leads from adapter set VAG 1594 A.
z Switch on ignition.
z The fuel pump should run.

z Activate remote control VAG 1348/3A for 30 seconds.

z Carry out measurement on all injectors.
z Once all four injectors have been actuated, place measuring glasses on a level surface.
z Specification for each injector: 145 +/-12 ml

z If the measured value for one or more of the injectors is outside the tolerance range, switch off the fuel
pump (by switching off ignition) and replace the defective injector, see FUEL INJECTORS,
REMOVING AND INSTALLING .
z If the measured values for all the injectors are outside the tolerance range, check the fuel pressure. See
SYSTEM PRESSURE, FUEL PRESSURE REGULATOR AND HOLDING PRESSURE,
CHECKING .

NOTE: When checking the injection quantity, also check the spray pattern. The spray
pattern should be the same for all the injectors.

z Install injectors together with fuel rail. See INSTALLING .

Fuel Pump (FP) Relay -J17-, testing and activating

Special tools and equipment

z VAG 1526 A
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z VAG 1594 A
z VAG 1598/31
z VAS 5051 with VAS 5051/1

Fig. 54: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Installation location overview, see COMPONENT LOCATIONS OVERVIEW

The fuel pump and some of the injection system components receive their voltage supply via fuel pump (FP)
relay -J17-.

Fuel pump (FP) relay -J17- will only close if the engine is turning over. In other words, the relay is only
Grounded (via the engine control module) when the engine control module is receiving engine revolution
impulses.

Test requirement:

z Battery voltage not less than 12.7 V

Testing operation of fuel pump relay

z Remove storage compartment on driver's side.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.
z Start output diagnostic test mode (see OUTPUT DIAGNOSTIC TEST MODE (FUNCTION 03) ) and
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activate evaporative emission (EVAP) canister purge -N80-.

z The fuel pump relay should pick up and the fuel pump should run. (Relay is located in relay
position 4 in micro central electrics on left of driver's footwell).

Fig. 55: Locating Fuel Pump Relay (Position 4)

Courtesy of AUDI OF AMERICA, INC.

A. - If the relay does not pick up:

{ See TESTING VOLTAGE SUPPLY TO FUEL PUMP RELAY .

{ See TESTING ACTIVATION OF FUEL PUMP RELAY .

B. - If the relay picks up but the fuel pump does not run:
{ See TESTING VOLTAGE SUPPLY TO FUEL PUMP AND OTHER COMPONENTS (via
fuel pump relay).

Testing voltage supply to fuel pump relay

z Disconnect fuel pump relay.

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Fig. 56: Identifying Fuel Pump Relay Contacts In Relay Carrier

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (voltage measurement range) to Ground and contact 17 on relay panel.
z Specification: approx. battery voltage

If the specification is not obtained:

z Replace central electrics unit

Testing activation of fuel pump relay

z Switch off ignition.

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Bridge contacts 1 and 65 on the test box using test leads from adapter set VAG 1594 A.
z Switch on ignition.
z The fuel pump relay should pick up. (Relay is located in relay position 4 in micro central electrics
on left of driver's footwell).

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Fig. 57: Locating Fuel Pump Relay

Courtesy of AUDI OF AMERICA, INC.

If the relay picks up now but not during the output diagnostic test mode:

z Install a new engine control module. See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

If the relay does not pick up:

z Switch off ignition.

z Disconnect cable bridge.
z Disconnect fuel pump relay.

Fig. 58: Identifying Fuel Pump Relay Contacts In Relay Carrier

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (voltage measurement range) as follows:

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FUEL PUMP RELAY CIRCUIT TEST - ACTIVATION

Central electrics on left of driver's footwell, relay position 4 Contact Measure against
19 Engine Ground

z Switch on ignition.
z Specification: approx. battery voltage

If the specification is not obtained:

z Check the wiring.

See appropriate System Wiring Diagrams article.

If the specification is obtained:

z Test for open circuit and short to positive or Ground in the following wiring connection:

FUEL PUMP RELAY CIRCUIT TEST - OPENS/SHORTS

Central electrics on left of driver's footwell, relay position 4 Contact Test box VAG 1598/31 Socket
16 65

z Correct any open/short circuit as necessary.

If no malfunction is found:

z Install a new fuel pump (FP) relay -J17-.

z Reconnect the engine control module.

Testing voltage supply to fuel pump and other components

z Remove fuse Nos. S228, S232, S234 and S243 (sockets 28, 32, 34 and 43) from fuse holder.

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Fig. 59: Identifying Fuse Holder

Courtesy of AUDI OF AMERICA, INC.

z Start output diagnostic test mode (see OUTPUT DIAGNOSTIC TEST MODE (FUNCTION 03) ) and
activate evaporative emission (EVAP) canister purge - N80-.
z For each of the following fuse positions in the fuse holder, connect the multimeter (voltage measurement
range) between Ground and one of the fuse contacts:

FUEL PUMP RELAY POWER SUPPLY FUSE SPECIFICATIONS

Fuse Specification (for one contact)
S228 Approx. battery voltage
S232 Approx. battery voltage
S234 Approx. battery voltage
S243 Approx. battery voltage

If the specifications are not obtained:

z Repeat the test on the other fuse contact.

If the specifications are again not attained:

z Check wiring

See appropriate System Wiring Diagrams article.

If no fault is found:
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z Install a new fuel pump (FP) relay -J17-.

z Install fuses.

Mass Air Flow (MAF) sensor - G70-, testing

Special tools and equipment

z VAG 1526 A
z VAG 1594 A
z VAG 1598/31
z VAS 5051 with VAS 5051/1

Fig. 60: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Installation locations overview, see COMPONENT LOCATIONS OVERVIEW

Requirements for test:

z Coolant temperature at least 80 °C

z Electrical consumers switched off (radiator fan must not run during the test)
z Air conditioner switched off

Testing operation

z Connect the vehicle diagnostic, testing and information system VAS 5051. See VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.

Display on VAS 5051:

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Fig. 61: Scan Tool Display - MAF Sensor, Testing (1 Of 3)

Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "04 - Basic settings" from the menu -1-.

Display on VAS 5051:

Fig. 62: Scan Tool Display - MAF Sensor, Testing (2 Of 3)

Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

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(figures up to 255)

z Using the keypad -2-, enter "002" to select Display group 002 and confirm entry with Q button.

Display on VAS 5051:

Fig. 63: Scan Tool Display - MAF Sensor, Testing (3 Of 3)

Courtesy of AUDI OF AMERICA, INC.

z Check readouts for evaluating engine load in display zones -3- and -4-.

DISPLAY GROUP 002: INTAKE AIR MASS AT IDLING SPEED WITH ENGINE AT NORMAL
OPERATING TEMPERATURE
Display zones
1 2 3 4
Display Group 002: Intake air mass at idling speed with engine at normal operating temperature
Display xxx RPM xxx % xx.x ms xxx.x g/s
Indicates Engine speed Load Avg. injection period Air mass
Specification 700 to 820 15.0 to 25.0 2.0 to 4.0 ms 2.0 to 4.5 g/s
RPM 1) %
Note --- --- If readout does not match specification, see
tableREADING DISPLAY GROUP 002

If the specification is obtained:

z Press the <- button to exit from diagnosis function "04 - Basic settings".

Reading Display Group 002

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READING DISPLAY GROUP 002

Display
zone 3 Possible cause Corrective action
Less than z Lower values can only occur
2.0 ms when vehicle is on overrun
More than z Load on engine due to z Eliminate load (air conditioner, power steering,
4.0 ms ancillaries alternator)
z Rough idling (engine not zTest spark plugs
running on all cylinders) z Test injectors, see FUEL INJECTORS,
TESTING
z Throttle valve control module - z Test throttle valve control module, see
J338 defective THROTTLE VALVE CONTROL
MODULE -J338-, TESTING
Display Possible cause Corrective action
zone 4
Less than z Large quantity of unmetered air z Check intake system for leaks (unmetered air),
2.0 g/s (air leak) between intake see INTAKE AIR SYSTEM, CHECKING
manifold and mass air flow FOR LEAKS (UNMETERED AIR)
sensor z Test voltage supply and wiring, see TESTING
z Voltage supply to mass air flow POWER SUPPLY TO MASS AIR FLOW
sensor or wiring to engine SENSOR
control module
More than Load on engine due to
z z Eliminate load (air conditioner, power steering,
4.5 g/s ancillaries alternator)
z Voltage supply to mass air flow z Test voltage supply and wiring, see TESTING
sensor or wiring to engine POWER SUPPLY TO MASS AIR FLOW
control module SENSOR

Testing power supply to mass air flow sensor

Requirements for test:

z Fuse for mass air flow sensor OK

See appropriate System Wiring Diagrams article.

z Fuel pump relay OK. Testing, see FUEL PUMP (FP) RELAY -J17-, TESTING AND
ACTIVATING .

NOTE: The mass air flow sensor receives its voltage supply via the fuel pump relay.

z Unplug connector from mass air flow sensor.

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Fig. 64: Identifying MAF Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (voltage measurement range) as follows:

MAF SENSOR CIRCUIT TEST - POWER SUPPLY

Connector Contact Measure against
2 Engine Ground

z Operate the starter briefly. (The engine can be allowed to start.)

z Specification: approx. battery voltage

If the specification is not attained:

z Test for open circuit or short to Ground in wiring between fuel pump relay and contact 2 on connector via
fuse.

See appropriate System Wiring Diagrams article.

z Correct short circuit or open circuit if necessary.

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Fig. 65: Identifying MAF Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect hand-held multimeter (voltage measurement range) between contacts 2 and 3 of connector.
z Operate the starter briefly. (The engine can be allowed to start.)
z Specification: approx. battery voltage

NOTE: Contact 3 on the connector is for the Ground connection from the engine
control module.

If the specification is not attained:

z Test the wiring. See TESTING WIRING FOR MASS AIR FLOW SENSOR .

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Fig. 66: Identifying MAF Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect hand-held multimeter (voltage measurement range) between contacts 3 and 4 of connector.
z Specification: approx. 5 V

If the specification is not attained:

z Test the wiring. See TESTING WIRING FOR MASS AIR FLOW SENSOR .

Testing wiring for mass air flow sensor

NOTE: The wiring test also tests the signal wire.

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself, see WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .

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Fig. 67: Identifying MAF Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Test for open circuit and short to positive or Ground in the following wiring connections:

MAF SENSOR CIRCUIT TEST - OPENS/SHORTS

Connector Contact Test box VAG1598/31 Socket
3 27
4 53
5 29

z Correct short circuit or open circuit if necessary.

z Test all wires for short circuits with each other.

If the wiring is OK:

z Fit a new mass air flow (MAF) sensor -G70-.

Intake air system, checking for leaks (unmetered air)

Special tools and workshop equipment and additional materials required:

z VAS 5051 with VAS 5051/1

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Fig. 68: Identifying Special Tool VAS 5051

Courtesy of AUDI OF AMERICA, INC.

z Engine leak detector spray G 001 800 A1

NOTE: z The vacuum in the intake system will cause the leak detector spray to be
drawn in with the outside air. The leak detector spray reduces the
ignitability of the mixture. This leads to a drop in engine speed and to a
significant increase of the CO content.
z The safety precautions listed on the container must be adhered to.

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.

Display on VAS 5051:

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Fig. 69: Scan Tool Display - Intake Air System, Checking For Leaks (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-.

Display on VAS 5051:

Fig. 70: Scan Tool Display - Intake Air System, Checking For Leaks (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

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(figures up to 255)

z Using the keypad -2-, enter "001" to select Display group 001 and confirm entry with Q key.

Display on VAS 5051:

Fig. 71: Scan Tool Display - Intake Air System, Checking For Leaks (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Note engine speed in display zone -1-.

z Systematically spray parts of the intake system with engine leak detector spray.

If the engine speed drops:

z Check sprayed areas of intake system for leaks and correct if necessary.
z Press the <- button to exit from diagnosis function "08 - Read data block".

Display on VAS 5051:

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Fig. 72: Scan Tool Display - Intake Air System, Checking For Leaks (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "06 - End output" from the menu -1-.
z Switch off ignition.

OXYGEN SENSOR CONTROL, TESTING

Oxygen sensor and oxygen sensor control (before catalytic converter), testing

Special tools and equipment

z VAG 1526 A
z VAG 1594 A
z VAG 1598/31
z VAG 1788/10
z VAS 5051 with VAS 5051/1

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Fig. 73: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Requirements for test:

z Exhaust system free of leaks

z Coolant temperature at least 80 °C

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.

Display on VAS 5051:

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Fig. 74: Scan Tool Display - O2 Sensor And O2 Sensor Control (Before Catalytic Converter), Testing (1
Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "04 - Basic settings" from the menu -1-.

Display on VAS 5051:

Fig. 75: Scan Tool Display - O2 Sensor And O2 Sensor Control (Before Catalytic Converter), Testing (2
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Of 5)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "030" to select Display group 030 and confirm entry with Q button.
z Adjust engine speed to 2000 RPM using VAG1788/10 RPM adjuster.

Display on VAS 5051:

Fig. 76: Scan Tool Display - O2 Sensor And O2 Sensor Control (Before Catalytic Converter), Testing (3
Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Check readout in display zone -1-.

NOTE: z The specified readouts can be obtained more quickly by increasing the
engine speed.
z The "oxygen sensor status" indicates the status of the oxygen sensor
control and the oxygen sensors.

DISPLAY GROUP 030: OXYGEN SENSOR STATUS

Display zones
1 2 3 4
Display Group 030: Oxygen sensor status
Display XXX XXX
Indicates Oxygen sensor status Bank 1, probe 1 Oxygen sensor status
Bank 1, probe 2
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Range 0 = off 0 = off

1 = on 1 = on
Specification 111 110
Note If readout does not match specification, see READING DISPLAY GROUP 033 .
If readout matches specification but Diagnostic Trouble Code (DTC) memory has
registered a fault Check oxygen sensor learned values and oxygen sensor control, see
"Testing oxygen sensor learned values and oxygen sensor control" below.

SIGNIFICANCE OF THREE -DIGIT DISPLAY IN DISPLAY GROUP 030

Significance of three -digit display in Display group 030
X X X Display zones 1 and 2
X Oxygen sensor control 0= inactive; 1= active
X Oxygen sensor condition: 0= inactive; 1= active
X Status of oxygen sensor heating: 0= inactive; 1= active

NOTE: The first digit in this three-digit display (heating) fluctuates between 0 and 1.

Display on VAS 5051:

Fig. 77: Scan Tool Display - O2 Sensor And O2 Sensor Control (Before Catalytic Converter), Testing (4
Of 5)
Courtesy of AUDI OF AMERICA, INC.

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z Before continuing the test, wait until the readout in display zone -1- shows "111" at least once.

Testing oxygen sensor learned values and oxygen sensor control

z Press UPARROW button twice to advance to Display group 032.

z Check readouts for oxygen sensor learned values in display zones -1- and -2-.

DISPLAY ZONESDISPLAY GROUP 032: OXYGEN SENSOR LEARNED VALUES

Display zones
1 2 3 4
Display Group 032: Oxygen sensor learned values
Display xx.x % xx.x %
Indicates Oxygen sensor learned value, Bank Oxygen sensor learned value, Bank 1,
1, Probe 1 at idling speed (additive) Probe 1 at part throttle (multiplicative)
Specification -6.0 to 6.0 % -10.0 to 10.0 %
Note If the specification is not attained, seeREADING DISPLAY GROUP 032

Display on VAS 5051:

Fig. 78: Scan Tool Display - O2 Sensor And O2 Sensor Control (Before Catalytic Converter), Testing (5
Of 5)
Courtesy of AUDI OF AMERICA, INC.

z Press UPARROW button to advance to Display group 033.

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z Check readouts for oxygen sensor control in display zones -1- and -2-.

DISPLAY GROUP 033: OXYGEN SENSOR CONTROL

Display zones
1 2 3 4
Display Group 033: Oxygen sensor control
Display xx.x % x.xxx V
Indicates Oxygen sensor control Bank 1, Probe 1 Oxygen sensor voltage Bank 1, Probe 1
Specification The readout should fluctuate by at least 0.130 to 3.600 V
2 % in a range between -10.0 to 10.0 %
Note If readout does not match specification, If readout does not match specification,
see FURTHER NOTES see READING DISPLAY GROUP 033

Note on display zone 2:

The display indicates the oxygen sensor voltage signal after it is processed and smoothed by the engine control
module. A display of 1.5 V equals lambda 1.

Further notes

If the readout in display zone 1 does not match the specification, or if the readout does not fluctuate by at least 2
%:

z Take car for a test drive to free oxygen sensor of any deposits, then repeat the test.

If the readout in display zone 1 still does not match the specification even after the test drive, or if the readout
still does not fluctuate by at least 2 %:

z Test the basic voltage. See READING DISPLAY GROUP 033 .

z Test the oxygen sensor heating before catalytic converter. See OXYGEN SENSOR (O2S) HEATER -
Z19- (BEFORE CATALYTIC CONVERTER), TESTING .
z Check the oxygen sensor (before the catalytic converter) for aging. See OXYGEN SENSOR AGING
(BEFORE CATALYTIC CONVERTER) TESTING .

Reading Display Group 032

READING DISPLAY GROUP 032 (OXYGEN SENSOR LEARNED VALUES BELOW

SPECIFICATION)
Display zone 1 / 2 Possible cause Corrective action
Oxygen sensor z Air leak in intake system z Check intake system for leaks and eliminate
learned values (pressure side between unmetered air, see INTAKE AIR
below specification turbocharger and intake SYSTEM, CHECKING FOR LEAKS
manifold) (UNMETERED AIR)
z Oil dilution z Change oil or drive car at moderate to high
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speeds on out-of-town roads

z High oil consumption
z Mass air flow sensor z Test mass air flow sensor, see MASS AIR
defective FLOW (MAF) SENSOR - G70-,
TESTING
z EVAP canister purge z Test EVAP canister purge regulator valve,
regulator valve sticking in see EVAPORATIVE EMISSION
open position (EVAP) CANISTER PURGE
REGULATOR VALVE, TESTING
z Fuel pressure too high z Test fuel pressure regulator, see SYSTEM
PRESSURE, FUEL PRESSURE
REGULATOR AND HOLDING
PRESSURE, CHECKING
z Injector does not close z Test injectors, see FUEL INJECTORS,
TESTING
z Oxygen sensor heating z Test oxygen sensor heating, see OXYGEN
defective SENSOR (O2S) HEATER - Z19-
z Oxygen sensor defective (BEFORE CATALYTIC
CONVERTER), TESTING

Reading Display Group 032

READING DISPLAY GROUP 032 (OXYGEN SENSOR LEARNED VALUES ABOVE

SPECIFICATION)
Display zone 1 / 2 Possible cause Corrective action
Oxygen sensor z Unmetered air in z Check intake system for leaks and eliminate
learned values above intake tract unmetered air, see INTAKE AIR SYSTEM,
specification CHECKING FOR LEAKS (UNMETERED
AIR)
z Fuel pressure too Test fuel pressure regulator, see SYSTEM
z
low PRESSURE, FUEL PRESSURE
REGULATOR AND HOLDING PRESSURE,
CHECKING
z Mass air flow z Test mass air flow sensor, see MASS AIR
sensor defective FLOW (MAF) SENSOR - G70-, TESTING
z Oxygen sensor z Test oxygen sensor heating, see OXYGEN
heating defective SENSOR (O2S) HEATER - Z19- (BEFORE
z Oxygen sensor
CATALYTIC CONVERTER), TESTING
defective
z Injector not z Test injectors, see FUEL INJECTORS,
opening or only TESTING
opening partially
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2000-2004 ENGINE PERFORMANCE Multiport Fuel Injection, 1.8L Turbo, AWP - TT

z EVAP canister z Test EVAP canister purge regulator valve, see

purge regulator EVAPORATIVE EMISSION (EVAP)
valve sticking CANISTER PURGE REGULATOR VALVE,
TESTING

Reading Display Group 033

READING DISPLAY GROUP 032 (DISPLAY ZONE 2)

Display
zone 2 Possible cause Corrective action
More than z Short to positive in wiring between z See TESTING OXYGEN SENSOR
4.800 V oxygen sensor and control module WIRING (before catalytic converter)
z Oxygen sensor defective

Less than z Replace oxygen sensor before catalytic

z Short to Ground in wiring between
0.130 V converter
oxygen sensor and control module
z Oxygen sensor defective

Testing basic voltage

z Unbolt connector cover -arrows-.

Fig. 79: Identifying HO2S Connector Cover

Courtesy of AUDI OF AMERICA, INC.

z Unplug 6-pin connector -1- (black) for heated oxygen sensor (HO2S) -G39-.

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Fig. 80: Locating Oxygen Sensor Connector

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (voltage measurement range) between contact 1 and 5.

Fig. 81: Identifying HO2S Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Specification: 0.400 to 0.500 V

z Switch off ignition.

If the specification is not obtained:

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z Test oxygen sensor wiring.

If the specification is obtained:

z Replace the heated oxygen sensor (HO2S) - G39-

Testing oxygen sensor wiring

z Unplug 6-pin connector -1- (black) for oxygen sensor (before catalytic converter) -G39.

Fig. 82: Locating Oxygen Sensor Connectors

Courtesy of AUDI OF AMERICA, INC.

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .

Fig. 83: Identifying HO2S Harness Connector Terminals

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Courtesy of AUDI OF AMERICA, INC.

z Test the following wiring connections for open circuits:

HO2S CIRCUIT TEST - OPENS

Connector Contact Test box VAG 1598/31 Socket
1 70
2 71
5 51
6 52

z Correct any open circuits.

See appropriate System Wiring Diagrams article.

z Test for short circuits between the wires.

If the wiring is OK:

z Fit a new engine control module. See ENGINE CONTROL MODULE (ECM) (WITHOUT METAL
ANTI-THEFT HOUSING), REPLACING .

Oxygen sensor aging (before catalytic converter) testing

Special tools and equipment

z VAG 1788/10 Engine speed adjuster

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Fig. 84: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

z VAS 5051 and VAS 5051/1

Fig. 85: Identifying Special Tool VAS 5051

Courtesy of AUDI OF AMERICA, INC.

Test requirement:

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z Coolant temperature at least 80 °C

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.

Display on VAS 5051:

Fig. 86: Scan Tool Display - Oxygen Sensor Aging, Before Catalytic Converter (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "04 - Basic settings" from the menu -1-.

Display on VAS 5051:

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Fig. 87: Scan Tool Display - Oxygen Sensor Aging, Before Catalytic Converter (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "034" to select Display group 034 and confirm entry with Q button.
z Set engine speed to 2000 RPM using VAG1788/10 RPM adjuster.

Display on VAS 5051:

Fig. 88: Scan Tool Display - Oxygen Sensor Aging, Before Catalytic Converter (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

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z Check readout in display zone -4-.

NOTE: This process can take a few minutes.

DISPLAY GROUP 034: DIAGNOSIS OF OXYGEN SENSOR AGEING

Display zones
1 2 3 4
Display group 034: Diagnosis of oxygen sensor ageing
Display xxxx RPM xxx °C x.x ---
Indicates Engine Exhaust Dynamic factor Status of diagnosis
speed temperature
Range Test OFF
Test ON
B1-P1 O.K.
B1-P1 n. O.K.
Specification 2000 RPM Higher than 350 ° Higher than 0.5 B1-P1 O.K.
C
Note If specification is not attained, refer to FURTHER
NOTES

Note on display zone 2:

Value calculated from engine speed and engine load.

Note on display zones 3 and 4:

The dynamic factor signifies the oxygen sensor ageing. Decreasing dynamic factor indicates increased oxygen
sensor ageing.

Further notes

If the readout in display zone 3 or 4 does not match the specification:

z Take car for a test drive to free oxygen sensor of any deposits, then repeat the test.

If the readout in display zone 3 or 4 still does not match the specification even after the test drive:

z Replace the heated oxygen sensor (HO2S) - G39-.

Oxygen Sensor (O2S) Heater - Z19- (before catalytic converter), testing

Special tools and equipment

z VAG 1526 A
z VAG 1594 A
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z VAG 1598/31

Fig. 89: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Requirements for test:

z Coolant temperature at least 80 °C

z Fuse for oxygen sensor heating OK

See appropriate System Wiring Diagrams article.

Test sequence

z Unbolt connector cover -arrows-.

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Fig. 90: Unbolting HO2S Connector Cover

Courtesy of AUDI OF AMERICA, INC.

z Unplug 6-pin connector -1- (black) for oxygen sensor (before catalytic converter) -G39.

Fig. 91: Locating Oxygen Sensor Connectors

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (resistance measurement range) between contacts 3 and 4.

z Specification: 2.5 to 10 (at room temperature)

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Fig. 92: Identifying HO2S Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

If the specification is not attained:

z Replace the heated oxygen sensor (HO2S) -G39-.

If the specification is obtained:

z Test voltage supply for oxygen sensor heating.

Testing voltage supply for oxygen sensor heating

z Connect multimeter (voltage measurement range) between contacts 3 and 4.

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Fig. 93: Identifying HO2S Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Start the engine.

z Specification: approx. battery voltage

NOTE: If required, observe Display Group 041, display zone 2 in the "Read measured
value block" function to find out when the engine control module is switching
the oxygen sensor heating on and off.

If no voltage is present:

Fig. 94: Identifying HO2S Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (voltage measurement range) as follows:

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HO2S HEATER CIRCUIT TEST - VOLTAGE TEST

Connector Contact Measure against
3 (positive) Vehicle Ground

z Operate starter briefly.

z Specification: approx. battery voltage

If there is still no voltage reading:

z Test for open circuit in wiring connection between fuel pump relay and contact 3 on connector via fuse:

See appropriate System Wiring Diagrams article.

If the voltage supply is OK:

Fig. 95: Identifying HO2S Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (voltage measurement range) as follows:

HO2S HEATER CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Measure against
4 (switched Ground connection for engine control module) Battery positive

z Start the engine.

z Specification: approx. battery voltage

NOTE: If required, observe Display Group 041, display zone 2 in the "Read measured
value block" function to find out when the engine control module is switching
the oxygen sensor heating on and off.
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z Switch off ignition.

If no voltage is present:

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuits in the following wiring connection:

Fig. 96: Identifying HO2S Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

HO2S HEATER CIRCUIT TEST - OPENS

Connector Contact Test box VAG 1598/31 Socket
4 5

z Correct any open circuits.

See appropriate System Wiring Diagrams article.

If the wiring connection is O.K. but the oxygen sensor heating still has no Ground connection:

z Install a new engine control module. See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen sensor and oxygen sensor control (after catalytic converter), testing

NOTE: The oxygen sensor before catalytic converter (Bank 1, Probe 1) holds the value
at lambda = 1. If the function of this oxygen sensor is impaired due to dirt or
overheating, the controlled value can alter. The oxygen sensor after catalytic
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converter (Bank 1, Probe 2) detects any deviations from lambda = 1. It corrects

variations (positive or negative) by increasing or reducing the oxygen sensor
control before catalytic converter accordingly.

Special tools and equipment

z VAG 1526 A
z VAG 1594 A
z VAG 1598/31
z VAG 1788/10
z VAS 5051 with VAS 5051/1

Fig. 97: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Requirements for test:

z Exhaust system free of leaks

z Coolant temperature at least 80 °C

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.

Display on VAS 5051:

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Fig. 98: Scan Tool Display - O2 Sensor And O2 Sensor Control, After Catalytic Converter, Testing (1 Of
4)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "04 - Basic settings" from the menu -1-.

Display on VAS 5051:

Fig. 99: Scan Tool Display - O2 Sensor And O2 Sensor Control, After Catalytic Converter, Testing (2 Of
4)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

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z Using the keypad -2-, enter "030" to select Display group 030 and confirm entry with Q button.
z Set engine speed to 2000 RPM using VAG1788/10 RPM adjuster.

Display on VAS 5051:

Fig. 100: Scan Tool Display - O2 Sensor And O2 Sensor Control, After Catalytic Converter, Testing (3 Of
4)
Courtesy of AUDI OF AMERICA, INC.

z Check readout in display zone -2-.

NOTE: z The specified readouts can be obtained more quickly by increasing the
engine speed.
z The "oxygen sensor status" indicates the status of the oxygen sensor
control and the oxygen sensors.

DISPLAY GROUP 030: OXYGEN SENSOR STATUS AT IDLING SPEED

Display zones
1 2 3 4
Display Group 030: Oxygen sensor status at idling speed
Display XXX XXX
Display Oxygen sensor status Bank 1, Probe 1 Oxygen sensor status Bank 1, Probe 2
Range 0 = off 0 = off
1 = on 1 = on
Specification 111 110
Note If readout does not match specification, seeOXYGEN SENSOR (O2S) HEATER
1 -Z29- (AFTER CATALYTIC CONVERTER), TESTING .

SIGNIFICANCE OF THREE -DIGIT DISPLAY IN DISPLAY GROUP 030

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Significance of three -digit display in Display group 030

X X X Display zones 1 and 2
X Oxygen sensor control 0= inactive; 1= active
X Oxygen sensor condition: 0= inactive; 1= active
X Status of oxygen sensor heating: 0= inactive; 1= active

NOTE: z The first digit of the three -digit display (heating) fluctuates between 0 and
1.
z The oxygen sensor control of oxygen sensor (after the catalytic converter;
B1-P2) is not active when the engine is not running under load.

Display on VAS 5051:

Fig. 101: Scan Tool Display - O2 Sensor And O2 Sensor Control, After Catalytic Converter, Testing (4 Of
4)
Courtesy of AUDI OF AMERICA, INC.

z Before continuing the test, wait until the readout in display zone -2- shows "110" at least once.

Testing oxygen sensor control (after catalytic converter)

Requirement

z Engine idling at 2000 RPM.

z Press the <- button.

Display on VAS 5051:

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Fig. 102: Scan Tool Display - Testing Oxygen Sensor Control, After Catalytic Converter (1 Of 2)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "037" to select Display group 037 and confirm entry with Q button.

Display on VAS 5051:

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Fig. 103: Scan Tool Display - Testing Oxygen Sensor Control, After Catalytic Converter (2 Of 2)
Courtesy of AUDI OF AMERICA, INC.

z Check oxygen sensor voltage in display zone -2-:

z Check the compensating value of the oxygen sensor control in display zone -3- and the result of the
diagnosis in display zone -4-.

DISPLAY GROUP 037: DIAGNOSIS OF OXYGEN SENSOR CONTROL SYSTEM

Display zones
1 2 3 4
Display group 037: Diagnosis of oxygen sensor control system
Display xxx % x.xxx V x.xx ---
Indicates Engine Oxygen sensor voltage Oxygen sensor Status of diagnosis
load Bank 1, Probe 2 compensating
value between
Bank 1, Probe 1
and Bank 1,
Probe 2
Range Test OFF
Test ON
SYST. O.K.
SYST. n. O.K.
Specification 12 to 0.100 to 0.950 V -0.02 to 0.02 SYST. O.K.
30 %
Note If the specification is If "SYST. n. O.K." appears on
not attained: Reading, the display, check DTC memory.
seeREADING See DIAGNOSTIC TROUBLE
DISPLAY GROUP CODE (DTC) MEMORY,
037 CHECKING AND ERASING .

Note on display zone 2:

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The oxygen sensor voltage (Bank 1, Probe 2) should remain more or less constant. Large voltage fluctuations
indicate that the catalytic converter is damaged.

Reading Display Group 037

READING DISPLAY GROUP 037

Display zone 2 Possible cause Corrective action
Approx. 0.450 z Open circuit in wire 4 z See TESTING BASIC VOLTAGE
V (constant) between oxygen sensor and
control module
z Open circuit in wire 3
between oxygen sensor and
control module
More than z Short to positive in wire 4 z Test wiring of oxygen sensor (after the
0.950 V between oxygen sensor and catalytic converter), see TESTING
control module OXYGEN SENSOR WIRING
Less than 0.100 z Short to Ground in wire 4
V between oxygen sensor and
control module

Further notes

If the readout in display zone 3 or 4 does not match the specification:

z Take car for a test drive to free oxygen sensor of any deposits, then repeat the test.

If the readout in display zone 3 or 4 still does not match the specification even after the test drive:

z Replace the oxygen sensor (before the catalytic converter) -G39.

NOTE: If the oxygen sensor voltage is OK and the compensating value is still above
0.02 even after a test drive, this points to excessive aging of the oxygen sensor
before catalytic converter.

Testing basic voltage

z Unbolt connector cover -arrows-.

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Fig. 104: Unbolting HO2S Connector Cover

Courtesy of AUDI OF AMERICA, INC.

z Unplug 4-pin connector -1- (brown) for oxygen sensor (O2S) behind three way catalytic converter (TWC)
- G130 -.

Fig. 105: Locating Oxygen Sensor Connectors

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (voltage measurement range) between contacts 3 and 4.

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Fig. 106: Identifying HO2S Harness Connector Terminals (HO2S Behind TWC)
Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

z Specification: 0.400 to 0.500 V

z Switch off ignition.

If the specification is not obtained:

z Test oxygen sensor wiring.

If the specification is obtained:

z Replace the oxygen sensor (O2S) behind three way catalytic converter (TWC) -G130-.

Testing oxygen sensor wiring

z Unplug 4-pin connector -1- (brown) for oxygen sensor (O2S) behind three way catalytic converter (TWC)
-G130 -.

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Fig. 107: Locating Oxygen Sensor Connectors

Courtesy of AUDI OF AMERICA, INC.

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself, see WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test the following wiring connections for open circuits:

Fig. 108: Identifying HO2S Harness Connector Terminals (HO2S Behind TWC)
Courtesy of AUDI OF AMERICA, INC.

HO2S BEHIND TWC CIRCUIT TEST - OPENS

Connector Contact Test box VAG 1598/31 Socket
3 68
4 69
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z Correct any open circuits.

See appropriate System Wiring Diagrams article.

z Test for short circuits between the wires.

If the wiring is OK:

z Install a new engine control module, see ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen sensor (O2S) heater 1 -Z29- (after catalytic converter), testing

Special tools and equipment

z VAG 1526 A
z VAG 1594 A
z VAG 1598/31

Fig. 109: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Requirements for test:

z Coolant temperature at least 80 °C

z Fuse for oxygen sensor heating OK

See appropriate System Wiring Diagrams article.

Test sequence

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z Unbolt connector cover -arrows-.

Fig. 110: Unbolting HO2S Connector Cover

Courtesy of AUDI OF AMERICA, INC.

z Unplug 4-pin connector -1- (brown) for oxygen sensor (O2S) behind three way catalytic converter (TWC)
-G130 -.

Fig. 111: Locating Oxygen Sensor Connectors

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter (resistance measurement range) between contacts 1 and 2.

z Specification: 6.4 to 47.5 ohm(at room temperature)

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Fig. 112: Identifying HO2S Behind TWC Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

If the specification is not attained:

z Replace the oxygen sensor (O2S) behind three way catalytic converter (TWC) -G130-.

If the specification is obtained:

z Test voltage supply for oxygen sensor heating.

Testing voltage supply for oxygen sensor heating

z Connect multimeter (voltage measurement range) between contacts 1 (positive) and 2 (Ground).

Fig. 113: Identifying HO2S Behind TWC Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.
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z Start the engine.

z Specification: approx. battery voltage

NOTE: If required, observe Display Group 041, display zone 4 in the "Read measured
value block" function to find out when the engine control module is switching
the oxygen sensor heating on and off.

If no voltage is present:

z Connect multimeter (voltage measurement range) as follows:

HO2S BEHIND TWC HEATING CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Measure against
1 (positive) Vehicle Ground

Fig. 114: Identifying HO2S Behind TWC Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Operate starter briefly.

z Specification: approx. battery voltage

If there is still no voltage reading:

z Test for open circuit in wiring connection between fuel pump relay and contact 1 on connector via fuse:

See appropriate System Wiring Diagrams article.

If the voltage supply is OK:

z Connect multimeter (voltage measurement range) as follows:

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HO2S BEHIND TWC HEATING CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Measure against
2 (switched Ground connection for engine control module) Battery positive

Fig. 115: Identifying HO2S Behind TWC Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Start the engine.

z Specification: approx. battery voltage (may fluctuate)

z Switch off ignition.

If no voltage is present:

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuits in the following wiring connection:

HO2S BEHIND TWC HEATING CIRCUIT TEST - OPENS

Connector Contact Test box VAG 1598/31 Socket
2 63

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Fig. 116: Identifying HO2S Behind TWC Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Correct any open circuits.

If the wiring connection is O.K. but the oxygen sensor heating still has no Ground connection:

z Install a new engine control module. See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

Oxygen sensor, removing and installing

Special tools and equipment

z Ring spanner set 3337

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Fig. 117: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

z Hot paste G 052 112 A3

Work sequence

z Unbolt connector cover -arrows-.

Fig. 118: Unbolting HO2S Connector Cover

Courtesy of AUDI OF AMERICA, INC.

z Unplug connector for oxygen sensor and move wiring clear.

z Designation of connectors:

Fig. 119: Locating Oxygen Sensor Connectors

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Courtesy of AUDI OF AMERICA, INC.

Heated Oxygen Sensor (HO2S) -G39- and oxygen sensor heating -Z19-: black;

Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130 - and oxygen sensor heating
-Z29 -: brown.

z Unscrew oxygen sensor using special tool 3337.

When installing, note the following points:

NOTE: z The screw thread on the oxygen sensor is coated with a special paste.
This paste must not be allowed to penetrate the openings on the probe.
z Tightening torque: 55 Nm.
z When installing, the oxygen sensor wire must be secured in exactly the
same position as before in order to avoid contact between the wire and the
exhaust pipe.

EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR VALVE, TESTING

Evaporative emission (EVAP) canister purge regulator valve -N80-, testing

Special tools and equipment

z VAG 1526 A
z VAG 1527 B
z VAG 1594 A
z VAG 1598/31
z VAS 5051 with VAS 5051/1

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Fig. 120: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Testing for leaks

Evaporative emission (EVAP) canister purge regulator valve -N80- remains closed when it is not receiving any
current.

z Disconnect hoses from EVAP valve but leave the electrical connector plugged in.
z Connect an auxiliary hose to one of the connections on the EVAP valve.
z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.
z Start output diagnostic test mode and select Evaporative emission (EVAP) canister purge regulator valve
-N80-. See OUTPUT DIAGNOSTIC TEST MODE (FUNCTION 03) .

Display on VAS 5051:

Fig. 121: Scan Tool Display - EVAP Canister Purge Regulator Valve, Testing
Courtesy of AUDI OF AMERICA, INC.

A. - 1st control element in test

1. - Evaporative emission (EVAP) canister purge regulator valve -N80-

z The valve should click...

z ...and open and close (can be checked by blowing into auxiliary hose).

If valve does not click:

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z Test internal resistance of EVAP valve.

If the valve does not open and close properly:

z Replace Evaporative emission (EVAP) canister purge regulator valve -N80-.

Testing internal resistance

z Unplug connector on EVAP valve.

z Connect multimeter between contacts 1 and 2 of valve (resistance measurement range).
z Specification: 22 to 30 ohm

Fig. 122: Measuring EVAP Canister Purge Regulator Valve Resistance

Courtesy of AUDI OF AMERICA, INC.

If the specification is not attained:

z Replace Evaporative emission (EVAP) canister purge regulator valve-N80-.

If the specification is obtained:

z See TESTING VOLTAGE SUPPLY .

Testing voltage supply

Requirements for test:

z Fuse for EVAP valve OK.

See appropriate System Wiring Diagrams article.

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z Fuel pump relay OK. Testing, see FUEL PUMP (FP) RELAY -J17-, TESTING AND
ACTIVATING .

NOTE: The EVAP valve receives its voltage supply via the fuel pump relay.

z Unplug connector on EVAP valve.

Fig. 123: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG 1527 B voltage tester as follows:

EVAP CANISTER PURGE REGULATOR VALVE CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Measure against
1 Engine Ground

z Operate the starter briefly. (The engine can be allowed to start.)

z The LED should light up.

If the LED does not light up:

z Test for open circuit in wiring connection between fuel pump relay and contact 1 on connector via fuse:

See appropriate System Wiring Diagrams article.

z Correct any open circuits.

If the LED lights up, see CHECKING ACTIVATION .

Checking activation

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z Connect VAG 1527 B voltage tester to contact 1 (positive) and contact 2 of the connector.

Fig. 124: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Start output diagnostic test mode and select evaporative emission (EVAP) canister purge regulator valve -
N80-. See OUTPUT DIAGNOSTIC TEST MODE (FUNCTION 03) .
z The LED should flash.

If the LED lamp does not flash or lights up continuously:

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31
z Test for open circuit and short to positive or Ground in the following wiring connections:

EVAP CANISTER PURGE REGULATOR VALVE CIRCUIT TEST - ACTIVATION

Connector Contact Test box VAG 1598/31 Socket
2 64

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Fig. 125: Identifying EVAP Canister Purge Regulator Valve Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Correct short circuit or open circuit if necessary.

If the wiring is OK:

z Install a new engine control module. See ENGINE CONTROL MODULE (ECM) (WITHOUT
METAL ANTI-THEFT HOUSING), REPLACING .

ELECTRONIC ENGINE POWER CONTROL (ELECTRONIC THROTTLE), TESTING

Operation of electronic throttle system

With the electronic throttle the throttle valve is not operated by a cable connected to the accelerator pedal. There
is no mechanical link between the accelerator and the throttle valve.

The position of the accelerator pedal is communicated to the engine control module by two accelerator position
senders (variable resistors, both fitted in a single housing) which are connected to the accelerator pedal.

The accelerator position (as determined by the driver) is one of the main input values for the engine control
module.

The throttle valve is actuated by a servomotor (throttle valve positioner) in the throttle valve control module
over the full range of engine speeds and load conditions.

The throttle valve positioner actuates the throttle valve according to the commands it receives from the engine
control module.

When the ignition is on and the engine is not running, the engine control module operates the throttle valve
positioner in exact accordance with the signals from the accelerator position senders. For example, when the
accelerator is pressed down half way, the throttle valve positioner opens the throttle valve by an equivalent
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amount, i.e. about half way.

When the engine is running (i.e. under load) the engine control module can open and close the throttle valve
freely (i.e. independently of the signals being sent by the accelerator position sender).

For example, the throttle valve might already be fully open even though the accelerator is only pressed down
half way. This has the advantage of preventing throttling losses at the throttle valve.

Under certain engine load conditions there is also a significant reduction in harmful emissions and noticeably
improved fuel consumption.

The engine control module can provide the optimum combination of throttle valve opening and charge pressure
in order to create the required torque.

The electronic throttle is not simply a combination of two or three components, but rather a complete system
comprising all the elements that together determine the position of the throttle valve and also control and
monitor it. For example, the accelerator position sender, throttle valve control module, EPC warning lamp,
engine control module etc.

Electronic throttle warning lamp in instrument cluster

NOTE: Electronic power control (EPC) warning lamp - K132- is also known as the EPC
warning lamp (EPC = electronic power control).

"EPC" stands for Electronic Power Control and refers to the electronic throttle control system.

Fig. 126: Locating Warning Lamp (EPC)

Courtesy of AUDI OF AMERICA, INC.

Installation location of EPC warning lamp

When the ignition is switched on the engine control module tests all the components whose functions relate to
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the electronic throttle system.

The engine control module activates the EPC warning lamp when the ignition is switched on. The warning lamp
will go out soon after the engine starts, provided that the engine control module does not detect any faults in the
electronic throttle system and the activation of the lamp via the engine control module is working properly.

If a fault is detected in the electronic throttle system while the engine is running, the engine control module will
activate the EPC warning lamp (see Fault Table for list of possible faults). At the same time a Diagnostic
Trouble Code (DTC) is stored in the Diagnostic Trouble Code (DTC) memory of the engine control module.

Electronic Power Control (EPC) warning lamp -K132-, testing

Testing operation of warning lamp

z Switch on ignition.
z The engine control module switches on the EPC warning lamp.

z Start the engine.

z If the Diagnostic Trouble Code (DTC) memory has not registered any faults relating to the
electronic throttle, the EPC warning lamp should go out shortly after starting the engine.

NOTE: The warning lamp signal is transmitted between engine control module and
instrument cluster via CAN-Bus. Testing data transfer between engine control
module and other control modules with CAN interface. See DATA EXCHANGE
BETWEEN ENGINE CONTROL MODULE AND OTHER CONTROL MODULES
WITH CAN-BUS INTERFACE, TESTING .

Throttle valve control module -J338-, testing

The housing for the throttle valve control module contains the following components:

z Throttle drive (power accelerator actuation) - G186-.

(This is an electric motor that is operated by the engine control module. The motor has to overcome
spring pressure in order to open the throttle valve.)

z Angle sensor -1- for throttle drive (power accelerator actuation) -G187-
z Angle sensor -2- for throttle drive (power accelerator actuation) -G188-

NOTE: z The housing for the throttle valve control module must not be opened.
z The angle sensors are potentiometers with variable resistance. They
inform the engine control module of the position of the throttle valve and
are completely independent of each other.
z It is not possible to adjust the potentiometers mechanically. Adjustments
can be made using vehicle diagnostic, testing and information system
VAS 5051, diagnosis function "04 - Basic settings".
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Throttle valve control module, adaptation

The adaptation process enables the engine control module to learn the different positions of the throttle valve
with the ignition switched on and the engine not running. These positions are stored in the control module. The
feedback signal indicating the position of the throttle valve comes from the two angle senders for throttle drive.

If the throttle valve control module -J338- or the engine control module is removed and refitted or replaced, or
if the power supply to the engine control module is interrupted, the adaption process must be performed.

The learning process (adaption process) is carried out:

z Automatically - if the ignition is switched on for at least 10 seconds without operating the starter or
depressing the accelerator, and if the engine control module registers a "learning requirement". (In this
case, however, there is no way of knowing whether the adaption process was successful or not.) The
engine control module will register a learning requirement if the previously stored voltage readings from
the angle sensors do not correspond (within a certain tolerance range) to the new voltage readings.
z By selecting "Basic settings" (function 04), Display Group 060 with the ignition switched on.

NOTE: The engine will not start while the automatic adaption process is being
performed.

Special tools and equipment

z VAS 5051 and VAS 5051/1

Fig. 127: Identifying Special Tool VAS 5051

Courtesy of AUDI OF AMERICA, INC.

Requirements:

z No faults stored in Diagnostic Trouble Code (DTC) memory. Interrogating Diagnostic Trouble Code
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(DTC) memory. See DIAGNOSTIC TROUBLE CODE (DTC) MEMORY, CHECKING AND
ERASING .
z Engine not running; ignition switched on.
z Accelerator not depressed.
z Coolant temperature 10 to 95 °C.
z Intake air temperature 10 to 90 °C.
z Voltage supply to engine control module more than 12.7 V. See VOLTAGE SUPPLY FOR
CONTROL MODULE, TESTING .

Work sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.

Display on VAS 5051:

Fig. 128: Scan Tool Display - Throttle Valve Control Module, Adaptation (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "04 - Basic settings" from the menu -1-.

Display on VAS 5051:

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Fig. 129: Scan Tool Display - Throttle Valve Control Module, Adaptation (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "060" to select Display group 060 and confirm entry with Q button.

When the Q key is pressed the current supply to the throttle valve positioner will be disconnected.

In this condition the throttle valve is pulled into an "emergency running" or default position by a spring in the
throttle valve control module. The values supplied by the two angle senders for this position are stored in the
engine control module.

The throttle valve is then opened by a predetermined amount. As soon as it reaches this position the current
supply to the throttle valve positioner is again disconnected. The spring should then close the throttle valve
mechanically to the previously learned default position within a specified period of time (spring test).

The throttle valve positioner then closes the throttle valve and the values supplied by the angle sensors in the
throttle valve control module are stored in the engine control module.

If the engine control module disconnects the current supply to the throttle valve positioner while the vehicle is
being driven, the result will be an increase in idling speed with fluctuating engine RPM (hunting) and very slow
throttle response.

Display on VAS 5051:

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Fig. 130: Scan Tool Display - Throttle Valve Control Module, Adaptation (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check display values for throttle valve control module (display zones -3- and -4-).

DISPLAY GROUP 060: ADAPTION OF THROTTLE VALVE CONTROL MODULE

Display zones
1 2 3 4
Display Group 060: Adaption of throttle valve control module
Display xx % xx % --- ---
Indicates Throttle Throttle Learning stage counter Adaption status
valve valve
angle angle
(angle (angle
sender 1) sender 2)
Range 0 to 8 ADP. runs
ADP. O.K.
ERROR
Specification 3 to 93 % 97 to 3 % 8 ADP O.K.
Note During the adaption If display reads "ERROR", check
process the learning stage DTC memory. See DIAGNOSTIC
counter should reach "8". TROUBLE CODE (DTC)
(Some of the digits may be MEMORY, CHECKING AND
skipped) ERASING .
If the specification is not attained:
Note, see below.

NOTE: The abbreviation "ADP" in display zone 4 stands for "Adaptation".

NOTE: If the adaptation process is interrupted by the control module, the cause could
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be one of the following:

z The throttle valve is unable to close completely (e.g. because of dirt).

z Battery voltage too low.
z Throttle valve control module or wiring is defective.
z The engine was started or the accelerator depressed during the adaption
process.
z Distortion of throttle valve housing (check bolts).

When the adaptation process is interrupted the message "Function is unknown or cannot be carried out at the
moment" will appear on the fault reader display. The adaption process will start again automatically the next
time the ignition is switched on (for several seconds).

z Press the <- button to exit from the function "04 - Basic settings"

Angle sensors for throttle drive, testing

Special tools and equipment

z VAG 1526 A
z VAG 1594 A
z VAG 1598/31
z VAS 5051 with VAS 5051/1

Fig. 131: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

The angle sensors for throttle drive (-G187 and - G188) inform the engine control module of the position of the
throttle valve. Both angle sensors are located in the throttle valve control module.

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Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.

Display on VAS 5051:

Fig. 132: Scan Tool Display - Angle Sensors For Throttle Drive, Testing (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-.

Display on VAS 5051:

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Fig. 133: Scan Tool Display - Angle Sensors For Throttle Drive, Testing (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "062" to select Display group 062 and confirm entry with Q button.

Display on VAS 5051:

Fig. 134: Scan Tool Display - Angle Sensors For Throttle Drive, Testing (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check display values for electronic throttle potentiometer voltages in display zones -1- and -2-.

DISPLAY GROUP 062: ELECTRONIC THROTTLE POTENTIOMETER VOLTAGES

Display zones
1 2 3 4
Display Group 062: Electronic throttle potentiometer voltages
Display xx % xx % xx % xx %
Indicates Throttle valve Throttle valve Accelerator position sender Accelerator
angle angle 1 position
(angle sender 1) (angle sender 2) sender 2
Specification 3 to 93 % 97 to 3 % 12 to 97 % 4 to 49 %

NOTE: The engine control module converts the voltage readings from the angle
senders into percentages of 5 V and displays them as percentages. (A supply
voltage of 5 V is equivalent to 100%.)

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z Observe display zones 1 and 2.

z Slowly depress accelerator to full throttle position.

The percentage value in display zone 1 should rise steadily between 3 and 93 % but without covering the full
range of values.

The percentage value in display zone 2 should fall steadily between 97 and 3 % but without covering the full
range of values.

NOTE: z The reason why the value in display zone 1 rises and the value in display
zone 2 falls is because the potentiometers (angle sensors) in the throttle
valve control module work in opposite directions.
z The percentage value for the first potentiometer increases as the voltage
rises toward 5 V because the voltage at this potentiometer increases as
the throttle valve opens.
z The percentage value for the second potentiometer decreases as the
voltage drops away from 5 V and toward 0 V because the voltage at this
potentiometer decreases as the throttle valve opens.

z Press the <- button to exit from the function "08 - Read data block".

If the display values do not appear as described:

z Test voltage supply and wiring to throttle valve control module. See TESTING VOLTAGE SUPPLY
TO THROTTLE VALVE CONTROL MODULE . Pay particular attention to the connectors, which
may have corroded or become detached.
z Test accelerator position sensors. See ACCELERATOR POSITION SENSORS, TESTING .

Testing voltage supply to throttle valve control module

z Unplug connector from throttle valve control module.

z Switch ignition on.
z Connect multimeter (voltage measurement range) as follows:

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Fig. 135: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

THROTTLE VALVE CONTROL MODULE CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Specification
2 + Ground approx. 5 V
2+6 approx. 5 V

If the specifications are not obtained:

z Test wiring between engine control module and throttle valve control module. See TESTING WIRING .

Testing wiring

z Unplug connector from throttle valve control module.

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuit and short to Ground or positive in the following wiring connections:

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Fig. 136: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

THROTTLE VALVE CONTROL MODULE CIRCUIT TEST - OPENS/SHORTS

Connector Contact Test box VAG 1598/31 Socket
1 92
2 83
3 117
4 84
5 118
6 91

z Correct any open/short circuit as necessary.

If no malfunction is detected:

z Install a new throttle valve control module.

Accelerator position sensors, testing

Special tools and equipment

z VAG 1526 A
z VAG 1594 A
z VAG 1598/31
z VAS 5051 with VAS 5051/1

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Fig. 137: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Accelerator position sensors -G79- and -G185 - are located on the accelerator pedal. Both senders inform the
engine control module of the driver's throttle requirement (pedal position), but each functions completely
independently of the other (redundancy principle). Both sensors are located in a single housing.

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.

Display on VAS 5051:

Fig. 138: Scan Tool Display - Accelerator Position Sensors, Testing (1 Of 3)

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Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-.

Display on VAS 5051:

Fig. 139: Scan Tool Display - Accelerator Position Sensors, Testing (2 Of 3)

Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "062" to select Display group 062 and confirm entry with Q button.

Display on VAS 5051:

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Fig. 140: Scan Tool Display - Accelerator Position Sensors, Testing (3 Of 3)

Courtesy of AUDI OF AMERICA, INC.

z Check display values for electronic throttle potentiometer voltages in display zones -3- and -4-.

DISPLAY GROUP 062: ELECTRONIC THROTTLE POTENTIOMETER VOLTAGES

Display zones
1 2 3 4
Display Group 062: Electronic throttle potentiometer voltages
Display xx % xx % xx % xx %
Indicates Throttle valve angle Throttle valve angle Accelerator position Accelerator position
(angle sender 1) (angle sender 2) sender 1 sender 2
Specification 3 to 93 % 97 to 3 % 12 to 97 % 4 to 49 %

NOTE: The engine control module converts the voltage readings from the angle
sensors into percentages of 5 V and displays them as percentages. (A supply
voltage of 5 V is equivalent to 100%.)

z Observe display zones 3 and 4.

z Slowly depress accelerator to full throttle position.

The percentage value in display zone 3 should rise steadily between 12 and 97 % but without covering the full
range of values.

The percentage value in display zone 4 should also rise steadily but without covering the full range of values (in
this case 4 to 49 %).

NOTE: The value shown in display zone 3 should always be about twice as high as the
value shown in display zone 4.

z Press the <- button to exit from the function "08 - Read data block".

If the display values do not appear as described:

z Test voltage supply and wiring to accelerator position senders

Testing voltage supply to accelerator position senders

z Remove storage compartment on driver's side.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Unplug connector for accelerator position sender.

z Switch ignition on.

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z Connect multimeter (voltage measurement range) as follows:

Fig. 141: Identifying Accelerator Position Sender Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

ACCELERATOR POSITION SENDER CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Specification
1 + Ground approx. 5 V
1+5 approx. 5 V
2 + Ground approx. 5 V
2+3 approx. 5 V

If the specifications are obtained:

z Test the signal wires.

If the specifications are not obtained:

z Test wiring between engine control module and accelerator position sensors. See TESTING WIRING .

Testing wiring

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuit and short to positive or Ground in the following wiring connections:

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Fig. 142: Identifying Accelerator Position Sender Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

ACCELERATOR POSITION SENDER CIRCUIT TEST - OPENS/SHORTS

Connector Contact Test box VAG 1598/31 Socket
1 72
2 73
3 36
4 35
5 33
6 34

z Correct any open/short circuit as necessary.

If no malfunction is detected in wiring:

z Replace accelerator position sensors.

See REMOVING AND INSTALLING ACCELERATOR PEDAL MODULE WITH THROTTLE

POSITION (TP) SENSOR -G79- AND SENDER -2-FOR ACCELERATOR PEDAL POSITION -
G185- .

Brake light switch and brake pedal position switch, testing

Special tools and equipment

z VAG 1526 A
z VAG 1527 B
z VAG 1594 A
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z VAG 1598/31
z VAS 5051 with VAS 5051/1

Fig. 143: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

NOTE: For safety reasons, the signal from the accelerator position sensor
(potentiometer) instructing the engine control module to open the throttle valve
is suppressed whenever the brake is operated. The engine control module
therefore needs the brake light signal and also the brake pedal signal.
If the brake is operated while the accelerator is held down at a constant
position, the engine is immediately governed down to idling speed. A defective
switch can cause the engine to be throttled back when this is not desired.

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.

Display on VAS 5051:

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Fig. 144: Scan Tool Display - Brake Light Switch And Brake Pedal Position Switch, Testing (1 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-.

Display on VAS 5051:

Fig. 145: Scan Tool Display - Brake Light Switch And Brake Pedal Position Switch, Testing (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "066" to select Display group 066 and confirm entry with Q button.

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Display on VAS 5051:

Fig. 146: SScan Tool Display - Brake Light Switch And Brake Pedal Position Switch, Testing (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check display value for brake light switch / rake pedal position switch (display zone -2-).

DISPLAY GROUP 066: SIGNALS TO ENGINE CONTROL MODULE

Display zones
1 2 3 4
Display Group 066: Signals to engine control module
Display xxx km/h XXXXXXXX xxx km/h XXXXXXXX
Indicates Actual road Switch positions Specified road Switch
speed speed positions
Range XXXXXX00
XXXXXX11
Specification XXXXXX00
(brake pedal not depressed)
XXXXXX11
(brake pedal depressed)
Note X = irrelevant
The switching points do not coincide
exactly.

z Press the <- button to exit from the function "08 - Read data block".

If the display values do not appear as described, go to TESTING SWITCHES .

Testing switches

z Remove storage compartment on driver's side.

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See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Unplug connector from brake light switch / brake pedal position switch.
z Connect multimeter (resistance measurement range) between contacts 1 and 4.

Fig. 147: Locating Brake Light/Brake Pedal Position Switch Terminals

Courtesy of AUDI OF AMERICA, INC.

z Specification: INFINITY ohm(no continuity)

z Depress the brake pedal.
z Specification: approx. 0 ohm

z Connect multimeter (resistance measurement range) between contacts 2 and 3.

z Specification: approx. 0 ohm

z Depress the brake pedal.

z Specification: INFINITY ohm (no continuity)

If the specifications are not obtained:

z Replace brake light switch / brake pedal position switch.

If the specifications are obtained, go to CHECKING VOLTAGE SUPPLY .

Checking voltage supply

z Connect VAG 1527 B voltage tester as follows:

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Fig. 148: Identifying Brake Light/Brake Pedal Position Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

BRAKE LIGHT/BRAKE PEDAL POSITION SWITCH CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Measure against
1 Body Ground

z The LED should light up.

BRAKE LIGHT/BRAKE PEDAL POSITION SWITCH CIRCUIT TEST - VOLTAGE SUPPLY

Connector Contact Measure against
2 Body Ground

z Switch on ignition.
z The LED should light up.

If the LED does not light up:

z Test for open circuit or short to Ground in wiring from contact 1 and/or contact 2 of connector:

See appropriate System Wiring Diagrams article.

z Correct short circuit or open circuit if necessary.

If the LED lights up, go to CHECKING ACTIVATION .

Checking activation

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
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z Test for open circuit and short to positive or Ground in the following wiring connections:

Fig. 149: Identifying Brake Light/Brake Pedal Position Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

BRAKE LIGHT/BRAKE PEDAL POSITION SWITCH CIRCUIT TEST - OPENS/SHORTS

Connector Contact Test box VAG1598/31 Socket
3 55
4 56

z Correct short circuit or open circuit if necessary.

Clutch vacuum vent valve switch -F36-, testing

Special tools and equipment

z VAG 1526 A
z VAG 1527 B
z VAG 1594 A
z VAG 1598/31
z VAS 5051 with VAS 5051/1

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Fig. 150: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

NOTE: This signal is used to avoid over -revving and load change jolts when
disengaging the clutch. It is also needed for the cruise control system.

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.

Display on VAS 5051:

Fig. 151: Scan Tool Display - Clutch Vacuum Vent Valve Switch, Testing (1 Of 3)
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Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-.

Display on VAS 5051:

Fig. 152: Scan Tool Display - Clutch Vacuum Vent Valve Switch, Testing (2 Of 3)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "066" to select Display group 066 and confirm entry with Q button.

Display on VAS 5051:

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Fig. 153: Scan Tool Display - Clutch Vacuum Vent Valve Switch, Testing (3 Of 3)
Courtesy of AUDI OF AMERICA, INC.

z Check display value for clutch vacuum vent valve switch (display zone -2-).

DISPLAY GROUP 066: SIGNALS TO ENGINE CONTROL MODULE

Display zones
1 2 3 4
Display Group 066: Signals to engine control module
Display xxx km/h XXXXXXXX xxx km/h XXXXXXXX
Indicates Actual road speed Switch positions Specified road speed Switch positions
Range XXXXX0XX
XXXXX1XX
Specification XXXXX0XX
(clutch pedal not depressed)
XXXXX1XX
(clutch pedal depressed)
Note X = irrelevant

z Press the <- button to exit from the function "08 - Read data block".

If the display values do not appear as described, go to TESTING SWITCH .

Testing switch

z Remove storage compartment on driver's side.

See DRIVER'S STORAGE COMPARTMENT, REMOVING .

z Unplug connector from clutch vacuum vent valve switch.

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Fig. 154: Locating Clutch Vacuum Vent Valve Switch Terminals

Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter for resistance measurement between contacts 1 and 2.

z Specification: approx. 0 ohm

z Depress the clutch pedal.

z Specification: INFINITY ohm (no continuity)

If the specification is not attained:

z Replace clutch vacuum vent valve switch.

If the specification is obtained, go to TESTING VOLTAGE SUPPLY .

Testing voltage supply

z Connect VAG 1527 B voltage tester as follows:

CLUTCH VACUUM VENT VALVE SWITCH - VOLTAGE SUPPLY

Connector Contact Measure against
1 Body Ground

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Fig. 155: Identifying Clutch Vacuum Vent Valve Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Switch on ignition.
z The LED should light up.

If the LED does not light up:

z Test for open circuit in wiring connection between connector terminal 1 to fuse:

See appropriate System Wiring Diagrams article.

z Correct any open circuit as necessary.

If the LED lights up, go to CHECKING ACTIVATION .

z Test activation.

Checking activation

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuit and short to positive or Ground in the following wiring connections:

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Fig. 156: Identifying Clutch Vacuum Vent Valve Switch Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

CLUTCH VACUUM VENT VALVE SWITCH - ACTIVATION

Connector Contact Test box VAG 1598/31 Socket
2 39

z Correct short circuit or open circuit if necessary.

AUXILIARY SIGNALS, TESTING

Special tools and equipment

z VAG 1526 A
z VAG 1527 B
z VAG 1594 A
z VAG 1598/31
z VAS 5051 with VAS 5051/1

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Fig. 157: Identifying Special Tools

Courtesy of AUDI OF AMERICA, INC.

Engine speed (RPM) signal, checking

NOTE: The engine speed signal is taken from contact 37 on the engine control module.
The signal is used for various functions including the rev counter display on the
instrument cluster.

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself, see WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuit and short to positive or Ground in the following wiring connection:

ENGINE SPEED (RPM) SIGNAL TO INSTRUMENT CLUSTER CIRCUIT TEST

Test box VAG 1598/31 Socket Instrument cluster Contact
37 See appropriate System Wiring Diagrams article.

z Correct short circuit or open circuit if necessary.

Vehicle speed signal, testing

NOTE: z The road speed signal is generated by the speedometer sender -G22 (on
the gearbox) and is processed in the instrument cluster.
z The processed signal goes to contact 54 on the engine control module and
is used for idling speed stabilization and for the damping of load change
jolts when changing gear.

Test requirement:

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z Speedometer (including display) must be functioning properly.

Test sequence

WARNING: To avoid accident risks when road testing the vehicle with test
equipment, always observe the relevant safety precautions, see
MULTIPORT FUEL INJECTION .

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.

Display on VAS 5051:

Fig. 158: Scan Tool Display - Vehicle Speed Signal, Testing (1 Of 3)

Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-

Display on VAS 5051:

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Fig. 159: Scan Tool Display - Vehicle Speed Signal, Testing (2 Of 3)

Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)

z Using the keypad -2-, enter "005" to select Display group 005 and confirm entry with Q button.

Display on VAS 5051:

Fig. 160: Scan Tool Display - Vehicle Speed Signal, Testing (3 Of 3)

Courtesy of AUDI OF AMERICA, INC.

z Take vehicle for a test drive and check whether the road speed appears in display zone -3-.

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z If the road speed does not appear, raise the vehicle (preferably using a lifting platform) until the front left
wheel is clear of the ground.
z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Connect VAG 1527 B voltage tester to sockets 3 (positive) and 54 (road speed signal) on test box VAG
1598/31.
z Switch on the ignition and turn the front left wheel by hand.
z The LED should flash very briefly.

If the LED does not flash:

z Test for open circuit and short to positive or Ground in the following wiring connection:

VSS SIGNAL TO INSTRUMENT CLUSTER CIRCUIT TEST

Test box VAG 1598/31 Socket Instrument cluster Contact
54 See appropriate System Wiring Diagrams article.

z Correct short circuit or open circuit if necessary.

Air conditioner compressor shut-off, testing

NOTE: z The air conditioner compressor signal informs the engine control module
that the compressor will be switched on in 140 ms.
z The engine control module can send a signal via the same wire to shut off
the air conditioner compressor.
z The engine control module will shut off the air conditioner compressor in
the following circumstances:
{ - Under heavy acceleration (full throttle in 1st gear)

{ - In emergency running mode (back-up)

{ - When the "Basic setting" function is started (function 04)

Requirements for test:

z Air conditioner okay

z No faults stored in Diagnostic Trouble Code (DTC) memory of engine control module
z Vehicle at room temperature (above +15 ° C)

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
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When doing this the engine should be idling.

Display on VAS 5051:

Fig. 161: Scan Tool Display - Air Conditioner Compressor Shut-Off, Testing (1 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-.

Display on VAS 5051:

Fig. 162: Scan Tool Display - Air Conditioner Compressor Shut-Off, Testing (2 Of 4)
Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

(figures up to 255)
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z Using the keypad -2-, enter "050" to select Display group 050 and confirm entry with Q button.

Display on VAS 5051:

Fig. 163: Scan Tool Display - Air Conditioner Compressor Shut-Off, Testing (3 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Switch off air conditioner.

z Specification for display zone -4-: "Compr.OFF"

z Switch on air conditioner by pressing "AUTO" key and select maximum warm or cold air setting. The
compressor should run.
z Specification for display zone -4-: "Compr. ON"

z Floor and release the accelerator quickly (short blip).

Display on VAS 5051:

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Fig. 164: Scan Tool Display - Air Conditioner Compressor Shut-Off, Testing (4 Of 4)
Courtesy of AUDI OF AMERICA, INC.

z Specification for display zone -4-: the display should change from "Compr.ON" to "Compr.OFF" for a
few seconds (air conditioner compressor shut-off during acceleration).

If the readout in display zone 4 is not as described:

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuit and short to positive or Ground in the following wiring connection:

A/C COMPRESSOR CUT-OFF CIRCUIT TEST

Test box VAG 1598/31 Socket AC operating and display unit -E87 Contact
41 See appropriate System Wiring Diagrams article.

z Correct short circuit or open circuit if necessary.

z If there are no malfunctions in the wiring, test operation of air conditioner.

See ON BOARD DIAGNOSTIC (OBD) .

Pressure switch/power steering -F88-, testing

The function of the pressure switch/power steering is to stabilize the idling speed when the steering wheel is on
full lock (left or right).

Test sequence

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE
DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND
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SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the engine should be idling.

Display on VAS 5051:

Fig. 165: Scan Tool Display - Pressure Switch/Power Steering, Testing (1 Of 2)

Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-.

Display on VAS 5051:

Fig. 166: Scan Tool Display - Pressure Switch/Power Steering, Testing (2 Of 2)

Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

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(figures up to 255)

z Using the keypad -2-, enter "056" to select Display group 056 and confirm entry with Q button.

Display on VAS 5051:

Fig. 167: Locating Pressure Switch/Power Steering

Courtesy of AUDI OF AMERICA, INC.

z Check readout for pressure switch/power steering (display zone -4-).

DISPLAY GROUP 056: IDLING SPEED STABILIZATION WITH ENGINE IDLING AT NORMAL
OPERATING TEMPERATURE
1 2 3 4
Display Group 056: Idling speed stabilization with engine idling at normal operating temperature
Display xxx RPM xxx RPM x.x % XXXXX
Indicates Actual engine Specified engine Idling speed Operating status
speed speed control
Torque
change
Range 0XXXX
1XXXX
Specification 0XXXX
(steering wheel in straight ahead
position or slightly turned)
1XXXX
(steering wheel at full lock, or turned
rapidly)
Note X = irrelevant

If the display values do not appear as described, go to TESTING SWITCH .

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Testing switch

z Unplug connector from pressure switch/power steering -F88 on power steering pump.
z Connect multimeter to switch (resistance measurement range).

Fig. 168: Identifying Pressure Switch/Power Steering

Courtesy of AUDI OF AMERICA, INC.

z Start the engine.

z Specification: INFINITY ohm (no continuity)

z Turn steering wheel to full lock (left and right).

z Specification: approx. 0 ohm

If the display does not change:

z Replace pressure switch/power steering -F88 -.

If the display changes:

z See TESTING WIRING .

Testing wiring

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself. See WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuit and short to positive or Ground in the following wiring connections:

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Fig. 169: IIdentifying Pressure Switch/Power Steering Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

PRESSURE SWITCH/POWER STEERING CIRCUIT TEST - OPENS/SHORTS

Connector Contact Test box VAG 1598/31 Socket
1 49
2 50

z Correct short circuit or open circuit if necessary.

Crash signal wiring, testing

The crash signal ("Crash switch-off triggered") is transmitted to the engine control module by the airbag control
module.

If the airbag control module transmits the crash signal to the engine control module (in case of an accident or if
a output diagnostic test mode for the airbag system is carried out), the engine control module switches off the
fuel pump. The engine stops but can be restarted immediately (e.g. to move the vehicle out of the danger zone).

z Connect test box VAG 1598/31 to wiring harness for engine control module. Do not connect to the
engine control module itself, see WIRING AND COMPONENT CHECK USING TEST BOX VAG
1598/31 .
z Test for open circuit and short to positive or Ground in the following wiring connection:

AIRBAG CONTROL MODULE -J234- TO ECM CIRCUIT TEST

VAG 1598/31 Test box Socket Airbag control module -J234 Contact
67 See appropriate System Wiring Diagrams article.

z Correct short circuit or open circuit if necessary.

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See appropriate System Wiring Diagrams article.

If no wiring malfunction is detected:

z Check DTC memory of airbag control module.

See appropriate Air Bag Restraint System article.

Fuel consumption signal for on-board computer, testing

NOTE: The fuel consumption signal is transmitted between engine control module and
instrument cluster via CAN bus. Testing data transfer between engine control
modules and other control modules with CAN interface. See DATA EXCHANGE
BETWEEN ENGINE CONTROL MODULE AND OTHER CONTROL MODULES
WITH CAN-BUS INTERFACE, TESTING .

Fuel level signal wiring, testing

NOTE: z The signal serves to determine the cause of certain detected malfunctions
(such as misfiring).
z The fuel level signal is transmitted between instrument cluster and engine
control module via CAN bus. Testing data transfer between engine control
module and other control modules with CAN interface. See DATA
EXCHANGE BETWEEN ENGINE CONTROL MODULE AND OTHER
CONTROL MODULES WITH CAN-BUS INTERFACE, TESTING .

Data exchange between engine control module and other control modules with CAN-bus interface, testing

NOTE: z The data exchange between the various control modules is carried out via
a data bus.
z The term "CAN-bus" refers to a system for transmitting and distributing
data.
z The wires which connect the control modules and convey the data
between them are called data wires.
z Data is transmitted via data wires in sequence, i.e. in a specific order to
the connected control modules (e.g. engine RPM and accelerator pedal
position).

Testing bus system

The DTC table indicates that the data exchange between the engine control module and other control modules
with CAN interface should be tested.

z Connect the vehicle diagnostic, testing and information system VAS 5051 (see VEHICLE

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DIAGNOSTIC, TESTING AND INFORMATION SYSTEM VAS 5051, CONNECTING AND

SELECTING FUNCTIONS ) and select the vehicle system "01 - Engine electronics" from the menu.
When doing this the ignition should be switched on.

Display on VAS 5051:

Fig. 170: Scan Tool Display - Pressure Switch/Power Steering, Testing (1 Of 5)

Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "08 - Read data block" from the menu -1-

Display on VAS 5051:

Fig. 171: Scan Tool Display - Pressure Switch/Power Steering, Testing (2 Of 5)

Courtesy of AUDI OF AMERICA, INC.

1. - Enter display group

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(figures up to 255)

NOTE: Data blocks 125 and 126 indicate the control modules which are part of the CAN
bus drive.

z Using the keypad -2-, enter "125" to select Display group 125 and confirm entry with Q button.

Display on VAS 5051:

Fig. 172: Scan Tool Display - Pressure Switch/Power Steering, Testing (3 Of 5)

Courtesy of AUDI OF AMERICA, INC.

z Check readouts in display zones -1- to -4-.

The display shows the control modules which are equipped with a CAN interface for data transfer with
the engine control module.

z No display: control module not equipped with CAN interface

z Display 1: control module with CAN interface forms part of the CAN bus

z Display 0: control module with CAN interface does not form part of the CAN-bus

z Press the UPARROW button to advance to Display group 126.

z Check readouts in Display group 126 in the same way.
z Press the <- button to exit from the function "08 - Read data block".

Display on VAS 5051:

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Fig. 173: Scan Tool Display - Pressure Switch/Power Steering, Testing (4 Of 5)

Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "06 - End output" from the menu -1-.

Display on VAS 5051:

Fig. 174: Scan Tool Display - Pressure Switch/Power Steering, Testing (5 Of 5)

Courtesy of AUDI OF AMERICA, INC.

z Select the diagnosis function "00 - Check all fault memories" from the menu -1-.
z The Diagnostic Trouble Code (DTC) memory of all on-board systems with self-diagnostic
capability will be read.

When a control module answers with its identification the number of stored DTCs appears on the display or
"No fault recognized".
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Any DTCs that are stored in one of the on -board systems will be displayed one after the other. VAS 5051 will
then transmit the next address word.

If DTCs have been stored relating to the "Data bus drive" or "Drive train data bus" or "CAN -bus":

z Check that the engine control module and other control modules with CAN interface are the correct
versions for the vehicle (check Part No. and coding).

If the correct control modules are installed:

z Check that multi -pin connectors for control modules are properly seated.

If the multi-pin connectors are properly seated:

z Test CAN bus system.

Testing a "two-wire bus system"

Three or more control modules communicating via a "two -wire bus system"

z Read out the DTCs stored in the control modules.

NOTE: This will help to trace a fault in the wiring.

Example 1:

From the DTCs present in the DTC memories, you can see that control module 1 has no connection to control
modules 2 or 3.

CONTROL MODULE 1 HAS NO CONNECTION TO CONTROL MODULES 2 OR 3

Control module Malfunctions present in DTC memory:
1 z No message from control module 2

z No message from control module 3

2 z No message from control module 1
3 z No message from control module 1

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Fig. 175: Schematic - Control Module 1 Has No Connection To Control Modules 2 Or 3

Courtesy of AUDI OF AMERICA, INC.

z Switch off ignition.

z Disconnect the control modules which are linked by the bus wires and check whether there is an open
circuit in one of the bus wires

See appropriate System Wiring Diagrams article.

z If no malfunction can be found in the bus wires replace control module 1.

Example 2:

From the DTCs present in the DTC memories, you can see that control module 2 has no connection to control
modules 1 or 3.

CONTROL MODULE 2 HAS NO CONNECTION TO CONTROL MODULES 1 OR 3

Control module Malfunctions present in DTC memory:
1 z No message from control module 2

2 z No message from control module 1

z No message from control module 3
3 z No message from control module 2

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Fig. 176: Schematic - Control Module 2 Has No Connection To Control Modules 1 Or 3

Courtesy of AUDI OF AMERICA, INC.

z Switch off ignition.

z Disconnect the control modules which are linked by the bus wires and check whether there is an open
circuit in one of the bus wires

See appropriate System Wiring Diagrams article.

z If no malfunction can be found in the bus wires replace control module 2.

Example 3:

From the DTCs present in the DTC memories, you can see that none of the control modules are able to transmit
or receive signals.

NONE OF THE CONTROL MODULES ARE ABLE TO TRANSMIT OR RECEIVE SIGNALS

Control module Malfunctions present in DTC memory:
1 z Data bus drive defective

2 z Data bus drive defective

3 z Data bus drive defective

z Switch off ignition.

z Disconnect the control modules which are linked by the bus wires and check for a short circuit to positive
or Ground in the bus wires

See appropriate System Wiring Diagrams article.

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Fig. 177: Schematic - Checking For Short To Power Or Ground In Bus Wires
Courtesy of AUDI OF AMERICA, INC.

If the cause of the malfunction "Data bus drive faulty" cannot be found in the data bus wires, check whether one of the control
modules is causing the malfunction.

Test requirement:

z Vehicle diagnostic, testing and information system VAS 5051 must be connected and "Vehicle self -
diagnosis" selected. See VEHICLE DIAGNOSTIC, TESTING AND INFORMATION SYSTEM
VAS 5051, CONNECTING AND SELECTING FUNCTIONS .

At this stage all the control modules which communicate via the CAN-bus are disconnected. The ignition is
switched off.

z Connect one of the control modules.

Display on VAS 5051:

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Fig. 178: Scan Tool Display

Courtesy of AUDI OF AMERICA, INC.

z Switch on ignition.
z Select the relevant vehicle system from menu -1-.
z Check and erase the Diagnostic Trouble Code (DTC) memory of the control module which has just been
connected.
z Press the <- button.
z Select the diagnosis function "06 - End output" from the menu -1-.
z Switch the ignition off and then on again.
z Leave the ignition switched on for 10 seconds. Then check the Diagnostic Trouble Code (DTC) memory
of the control module that has just been connected, using Scan Tool.
z If the malfunction "Data bus drive faulty" is now indicated, replace the control module which has just
been connected.
z If the malfunction "Data bus drive faulty" is not indicated, connect the next control module, and repeat
the above procedure.

VACUUM SYSTEM LAYOUT

The following list pertains to Fig. 179 .

1. - Secondary air injection (AIR) solenoid valve -N112-

2. - Crankcase breather
3. - Secondary air injection (AIR) pump motor -V101-
4. - Throttle valve control module -J338 -
5. - Non-return valves for EVAP canister
z Between EVAP canister and intake manifold

z Between EVAP canister and intake pipe upstream of turbocharger

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z Install with light and dark sides in the positions shown in the illustration. Arrow points in direction
of flow.
6. - Charge air cooler
z With charge air pressure sensor -G31

7. - Check valve
z Inserted into the vacuum reservoir

8. - Vacuum reservoir
z Leak detection pump (LDP) - V144-

9. - Evaporative Emission canister purge regulator valve -N80-

10. - Test connection
11. - Leak detection pump (LDP) - V144-
z Installation position: In front right wheelhousing behind the wheelhousing liner

z Checking:

See LEAK DETECTION PUMP (LDP)-V144-, CHECKING .

12. - to EVAP canister

13. - to EVAP canister
14. - Turbocharger
15. - Vacuum unit for charge pressure control
16. - Mechanical air recirculation valve
17. - Brake booster
18. - Non-return valve
z Between brake booster and intake manifold

z Install with light and dark sides in the positions shown in the illustration. Arrow points in direction
of flow.
19. - Wastegate bypass regulator valve -N75-
20. - Mass air flow (MAF) sensor - G70-
21. - Air cleaner
22. - Crankcase breather pressure regulating valve
23. - Combination valve for secondary air system
24. - Vacuum reservoir
z Bolted to cylinder head cover

25. - Fuel pressure regulator

26. - Intake manifold
z With intake air temperature (IAT) sensor -G42-

27. - Non-return valve

z Install with light and dark sides in the positions shown in the illustration. Arrow points in direction
of flow.
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28. - Recirculating valve for turbocharger -N249-

Fig. 179: Engine Vacuum Diagram And Components

Courtesy of AUDI OF AMERICA, INC.

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2000-2004 ENGINE PERFORMANCE

Multiport Fuel Injection (MFI), Generic Scan Tool: 1.8L AMU, BEA, ATC, AWP - TT

MULTIPORT FUEL INJECTION (MFI)

FUEL INJECTION, SERVICING

General Notes on Fuel Injection

For servicing ignition, see IGNITION, SERVICING .

NOTE: z The Engine Control Module (ECM) is equipped with an On Board

Diagnostic (OBD) Always check DTC memory first, before performing
repairs or troubleshooting. Vacuum hoses and connections should also be
checked (unmetered air).
z For the electric components to work properly, a voltage of at least 11.5 V
is required.
z Do not use any silicone sealant. Traces of silicone components which are
sucked into the engine are not burned there, and they damage the oxygen
sensor.
z The battery must only be disconnected and connected with the ignition
switched off, since the Engine Control Module (ECM) can otherwise be
damaged.
z Fuel hoses at engine must only be secured with spring-type clamps. The
use of clamping collars or screw clamps is not permitted.
z VAS5024A spring clip installation tool is recommended for installing
spring-type clips.

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Fig. 1: Identifying VAS5024A Spring Clip Installation Tool

Courtesy of AUDI OF AMERICA, INC.

z It is possible that the control module will recognize a malfunction and

store a DTC during some tests. Therefore the following work steps must
be performed in the mentioned sequence after ending all tests and repairs.
{ - Check DTC memory. See DIAGNOSTIC MODE 3: CHECK DTC
MEMORY .
{ - Erase DTC memory. See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
{ - For completion, generate readiness code. See READINESS CODE,
GENERATING .

See SAFETY PRECAUTIONS .

See RULES OF CLEANLINESS .

See TECHNICAL DATA .

Overview of component locations

Vehicles with engine code AMU

See VEHICLES WITH ENGINE CODE ATC .

See VEHICLES WITH ENGINE CODE AWP .

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See VEHICLES WITH ENGINE CODE BEA .

Components A and B are not depicted in the exploded view Fig. 2 .

A. - Leak detection pump (LDP) -V144- (behind front right wheel housing liner)
z Checking, see CHECK LEAK DETECTION PUMP (LDP)

B. - Evaporative Emission (EVAP) Canister Purge Solenoid Valve -N115- (at EVAP canister, below
spare tire well, accessible from below)
z Checking, see EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR
VALVE, CHECKING .

NOTE: The following list refers to items in Fig. 2 .

1. - 4-pin harness connector

z For Heated Oxygen Sensor (HO2S) -G39- and Oxygen Sensor (O2S) Heater -Z19-

z Component location: On right at bulkhead

z Heated Oxygen Sensor (HO2S) -G39- (bank 1, sensor 1) is threaded directly into the exhaust
manifold
2. - Motronic Engine Control Module (ECM) -J220-
z Checking voltage supply, see VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE
(ECM), CHECKING
z Replace. See REPLACING ENGINE CONTROL MODULE (ECM) .

3. - Ignition coils
z Cylinder 1 Ignition Coil -N-

z Cylinder 2 Ignition Coil 2 - N128-

z Cylinder 3 Ignition Coil 3 - N158-

z Cylinder 4 Ignition Coil 4 -N163-

z Checking, see IGNITION COILS WITH POWER OUTPUT STAGE, CHECKING

4. - Recirculating valve for turbocharger -N249-

z Checking, see RECIRCULATING VALVE FOR TURBOCHARGER, CHECKING

5. - Combination valve for secondary air injection (AIR)

6. - Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position - G185 -
7. - Brake Light Switch -F- and Brake Pedal Switch (cruise control/Diesel Direct Fuel Injection) -F47-
8. - Clutch Vacuum Vent Valve Switch -F36-
9. - Electronic Power Control (EPC) Warning Lamp -K132-
z "EPC" warning lamp

10. - Secondary Air Injection (AIR) Pump Relay -J299- and main relay (Motronic Engine Control
Module (ECM) Power Supply Relay -J271-)
z Below cover, on left at bulkhead

11. - Mass Air Flow (MAF) Sensor -G70-

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12. - Wastegate Bypass Regulator Valve -N75-

z Checking, see WASTEGATE BYPASS REGULATOR VALVE, CHECKING

13. - Engine Coolant Temperature (ECT) Sensor -G62-

14. - Fuel pressure regulator
15. - Knock Sensor (KS) 2 -G66-
16. - Charge Air Pressure Sensor -G31-
z Component location:

Screwed in, above in charge air cooler

z Headlight must be removed in order to access charge air pressure sensor.

z Checking, see CHARGE AIR PRESSURE SENSOR, CHECKING

17. - Engine Speed (RPM) Sensor -G28-

18. - Throttle Valve Control Module -J338-
z With Throttle drive (power accelerator actuation) - G186 -, Angle sensor -1- for throttle drive
(power accelerator actuation) - G187 -, and Angle sensor -2- for throttle drive (power accelerator
actuation) - G188 -
19. - Intake Air Temperature (IAT) Sensor -G42-
20. - 3-pin harness connector
z for Knock Sensor (KS) 1 - G61-

z for Engine Speed (RPM) Sensor -G28-

z for Knock Sensor (KS) 2 - G66-

21. - Secondary Air Injection (AIR) Solenoid Valve -N112-

22. - Cylinder 1 Fuel Injector -N30- through Cylinder 4 Fuel Injector -N33-
23. - Knock Sensor (KS) 1 -G61-
24. - Secondary Air Injection (AIR) Pump Motor -V101-
z Checking, see SECONDARY AIR INJECTION (AIR) PUMP MOTOR, CHECKING

25. - Pressure switch/power steering -F88 -

26. - Camshaft Position (CMP) Sensor 2 -G163-
27. - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
z Checking, see EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR
VALVE, CHECKING

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Fig. 2: Fuel Injection System Component Locations - Engine Code AMU

Courtesy of AUDI OF AMERICA, INC.

Vehicles with engine code ATC

NOTE: The following list refers to items in Fig. 3 .

1. - Leak detection pump (LDP) - V144-

z Below front right wheel housing liner:

z Checking, see CHECK LEAK DETECTION PUMP (LDP)

2. - Heated Oxygen Sensor (HO2S) -G39- before catalytic converter, 50 Nm and Oxygen Sensor (O2S)
Behind Three Way Catalytic Converter (TWC) -G130 -, 50 Nm
z Both oxygen sensors and their respective harness connectors are accessible from below after
vehicle has been lifted.
3. - Camshaft Position (CMP) Sensor 2 -G163-
4. - Cylinder 1 Fuel Injector -N30- through Cylinder 4 Fuel Injector -N33-
5. - Motronic Engine Control Module (ECM) -J220-
z Checking voltage supply. See VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE
(ECM), CHECKING .
z Replace. See REPLACING ENGINE CONTROL MODULE (ECM) .

6. - Ignition coils
z Cylinder 1 Ignition Coil -N-

z Cylinder 2 Ignition Coil 2 - N128-

z Cylinder 3 Ignition Coil 3 - N158-

z Cylinder 4 Ignition Coil 4 - N163-

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z Checking, see IGNITION COILS WITH POWER OUTPUT STAGE, CHECKING

7. - Wastegate Bypass Regulator Valve -N75-
z Checking, see WASTEGATE BYPASS REGULATOR VALVE, CHECKING

8. - Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position - G185 -
9. - Brake Light Switch -F- and Brake Pedal Switch (cruise control/Diesel Direct Fuel Injection) -F47-
10. - Clutch Vacuum Vent Valve Switch -F36-
11. - Malfunction Indicator Lamp (MIL) -K83-
12. - Electronic Power Control (EPC) Warning Lamp -K132-
z "EPC" warning lamp

13. - Secondary Air Injection (AIR) Pump Relay -J299-

z under a black plastic cover; directly behind Mass Air Flow (MAF) sensor

14. - Mass Air Flow (MAF) Sensor -G70-

15. - Engine Coolant Temperature (ECT) Sensor -G62-
16. - Fuel pressure regulator
17. - Engine Speed (RPM) Sensor -G28-
18. - Knock Sensor (KS) 2 -G66-
19. - Recirculating valve for turbocharger -N249-
z Checking, see RECIRCULATING VALVE FOR TURBOCHARGER, CHECKING

20. - 3-pin harness connector

z for Knock Sensor (KS) 1 - G61-

z for Engine Speed (RPM) Sensor -G28-

z for Knock Sensor (KS) 2 - G66-

21. - Secondary Air Injection (AIR) Solenoid Valve -N112-

22. - Knock Sensor (KS) 1 -G61-
23. - Intake Air Temperature (IAT) Sensor -G42-
24. - Secondary Air Injection (AIR) Pump Motor -V101-
z Checking, see SECONDARY AIR INJECTION (AIR) PUMP MOTOR, CHECKING

25. - Pressure switch/power steering -F88 -

26. - Throttle Valve Control Module -J338-
z With Throttle drive (power accelerator actuation) - G186 -, Angle sensor -1- for throttle drive
(power accelerator actuation) - G187 -, and Angle sensor -2- for throttle drive (power accelerator
actuation) - G188 -
27. - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
z Checking, see EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR
VALVE, CHECKING
28. - Charge Air Pressure Sensor -G31-
z Component location:

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Screwed in, above in charge air cooler

z Headlight must be removed in order to access charge air pressure sensor.

z Checking, see CHARGE AIR PRESSURE SENSOR, CHECKING

Fig. 3: Fuel Injection System Component Locations - Engine Code ATC

Courtesy of AUDI OF AMERICA, INC.

Vehicles with engine code AWP

NOTE: The following list refers to items in Fig. 4 .

1. - Leak detection pump (LDP) - V144-

z below front right wheel housing liner

z Checking, see CHECK LEAK DETECTION PUMP (LDP)

2. - Heated Oxygen Sensor (HO2S) -G39- before catalytic converter, 50 Nm and Oxygen Sensor (O2S)
Behind Three Way Catalytic Converter (TWC) -G130 -, 50 Nm
z Both oxygen sensors and their respective harness connectors are accessible from below after
vehicle has been lifted.
3. - Camshaft Position (CMP) Sensor -G40-
z Checking, see CHECK CAMSHAFT POSITION (CMP) SENSOR

4. - Fuel injectors
z Cylinder 1 Fuel Injector - N30-

z Cylinder 2 Fuel Injector - N31-

z Cylinder 3 Fuel Injector - N32-

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z Cylinder 4 Fuel Injector - N33-

5. - Motronic Engine Control Module (ECM) -J220-
z Checking voltage supply. See VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE
(ECM), CHECKING .
z Replace. See REPLACING ENGINE CONTROL MODULE (ECM) .

6. - Ignition coils
z Cylinder 1 Ignition Coil -N-

z Cylinder 2 Ignition Coil 2 - N128-

z Cylinder 3 Ignition Coil 3 - N158-

z Cylinder 4 Ignition Coil 4 - N163-

z Checking, see IGNITION COILS WITH POWER OUTPUT STAGE, CHECKING

7. - Wastegate Bypass Regulator Valve -N75-

z Checking, see WASTEGATE BYPASS REGULATOR VALVE, CHECKING

8. - Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position - G185 -
9. - Brake Light Switch -F- and Brake Pedal Switch (cruise control/Diesel Direct Fuel Injection) -F47-
10. - Clutch Vacuum Vent Valve Switch -F36-
11. - Instrument cluster
z with Malfunction Indicator Lamp (MIL) -K83-.

z with Electronic Power Control (EPC) Warning Lamp -K132- (EPC warning lamp)

12. - Motronic Engine Control Module (ECM) Power Supply Relay -J271 -
13. - Secondary Air Injection (AIR) Pump Relay -J299-
14. - Mass Air Flow (MAF) Sensor -G70-
15. - Engine Coolant Temperature (ECT) Sensor -G62-
z If necessary, release pressure in cooling system before removing

16. - Valve -1- for camshaft adjustment -N205-

z Checking, see CAMSHAFT ADJUSTMENT VALVE, CHECKING

17. - Fuel pressure regulator

18. - Engine Speed (RPM) Sensor -G28-
z Checking, see CHECK ENGINE SPEED (RPM) SENSOR

19. - Knock Sensor (KS) 2 -G66-

20. - Recirculating valve for turbocharger -N249-
z Checking, see RECIRCULATING VALVE FOR TURBOCHARGER, CHECKING

21. - 3-pin harness connector

z for Knock Sensor (KS) 1 - G61-

z for Engine Speed (RPM) Sensor -G28-

z for Knock Sensor (KS) 2 - G66-

22. - Secondary Air Injection (AIR) Solenoid Valve -N112-

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23. - Knock Sensor (KS) 1 -G61-

24. - Intake Air Temperature (IAT) Sensor -G42-
25. - Secondary Air Injection (AIR) Pump Motor -V101-
z Checking, see SECONDARY AIR INJECTION (AIR) PUMP MOTOR, CHECKING

26. - Pressure switch/power steering -F88 -

27. - Throttle Valve Control Module -J338-
z With Throttle drive (power accelerator actuation) - G186 -, Angle sensor -1- for throttle drive
(power accelerator actuation) - G187 -, and Angle sensor -2- for throttle drive (power accelerator
actuation) - G188 -
28. - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
z Checking, see EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR
VALVE, CHECKING
29. - Charge Air Pressure Sensor -G31-
z screwed in, above in charge air cooler

z Checking, see CHARGE AIR PRESSURE SENSOR, CHECKING

Fig. 4: Fuel Injection System Component Locations - Engine Code AWP

Courtesy of AUDI OF AMERICA, INC.

Vehicles with engine code BEA

NOTE: The following list refers to items in Fig. 5 .

1. - Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130 -, 50 Nm
2. - 4-pin harness connector
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z for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen
Sensor (O2S) Heater 1 -Z29- (brown)
3. - Heated Oxygen Sensor (HO2S) -G39- before catalytic converter, 50 Nm
4. - 6-pin harness connector
z for Heated Oxygen Sensor (HO2S) -G39- before catalytic converter and Oxygen Sensor (O2S)
Heater -Z19-(black)
5. - Motronic Engine Control Module (ECM) -J220-
z Checking voltage supply, see VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE
(ECM), CHECKING
z Replace. See REPLACING ENGINE CONTROL MODULE (ECM) .

6. - Ignition coils
z Cylinder 1 Ignition Coil -N-

z Cylinder 2 Ignition Coil 2 - N128-

z Cylinder 3 Ignition Coil 3 - N158-

z Cylinder 4 Ignition Coil 4 - N163-

z Checking, see IGNITION COILS WITH POWER OUTPUT STAGE, CHECKING

7. - Recirculating valve for turbocharger -N249-

z Checking, see RECIRCULATING VALVE FOR TURBOCHARGER, CHECKING

8. - Combination valve for secondary air injection (AIR)

9. - Throttle Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position -G185-
10. - Brake Light Switch -F- and Brake Pedal Switch (cruise control/Diesel Direct Fuel Injection) -F47-
11. - Clutch Vacuum Vent Valve Switch -F36-
12. - Instrument cluster
z with Electronic Power Control (EPC) Warning Lamp -K132-

z with Malfunction Indicator Lamp (MIL) -K83-

13. - Motronic Engine Control Module (ECM) Power Supply Relay -J271 -
14. - Mass Air Flow (MAF) Sensor -G70-
15. - Wastegate Bypass Regulator Valve -N75-
z Checking, see WASTEGATE BYPASS REGULATOR VALVE, CHECKING

16. - Engine Coolant Temperature (ECT) Sensor -G62-

z If necessary, release pressure in cooling system before removing

17. - Valve -1- for camshaft adjustment -N205-

z Checking, see CAMSHAFT ADJUSTMENT VALVE, CHECKING

18. - Fuel pressure regulator

19. - Knock Sensor (KS) 2 -G66-
20. - Charge Air Pressure Sensor -G31-
z screwed in, above in charge air cooler

z Checking, see CHARGE AIR PRESSURE SENSOR, CHECKING

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21. - Engine Speed (RPM) Sensor -G28-

22. - Throttle Valve Control Module -J338-
z With Throttle drive (power accelerator actuation) -G186-, Angle sensor -1- for throttle drive (power
accelerator actuation) - G187-, and Angle sensor -2- for throttle drive (power accelerator actuation)
-G188-
23. - Intake Air Temperature (IAT) Sensor -G42-
24. - 3-pin harness connector
z for Engine Speed (RPM) Sensor -G28-

25. - Sensor -1- for exhaust temperature -G235-

z Temperature sensor is in turbocharger

26. - Fuel injectors

z Cylinder 1 Fuel Injector - N30-

z Cylinder 2 Fuel Injector - N31-

z Cylinder 3 Fuel Injector - N32-

z Cylinder 4 Fuel Injector - N33-

27. - Secondary Air Injection (AIR) Pump Motor -V101-

z Checking, see SECONDARY AIR INJECTION (AIR) PUMP MOTOR, CHECKING

28. - Knock Sensor (KS) 1 -G61-

29. - Pressure switch/power steering -F88 -
30. - Camshaft Position (CMP) Sensor -G40-
z Checking, see CHECK CAMSHAFT POSITION (CMP) SENSOR

31. - Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-

z Checking, see EVAPORATIVE EMISSION (EVAP) CANISTER PURGE REGULATOR
VALVE, CHECKING

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Fig. 5: Fuel Injection System Component Locations - Engine Code BEA

Courtesy of AUDI OF AMERICA, INC.

Air filter, disassembling and assembling

NOTE: The following list refers to items in Fig. 6 .

1. - Seal
2. - Mass Air Flow (MAF) Sensor -G70-
3. - Phillips-head screw
4. - Air duct
5. - 5-pin harness connector
6. - Phillips-head screw
7. - Air filter, upper portion
8. - Filter element
9. - Nut -10 Nm
10. - Air intake connection
11. - Air filter, lower portion
12. - Hex-bolt, -10 Nm

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Fig. 6: Explode View Of Air Filter Components

Courtesy of AUDI OF AMERICA, INC.

Fuel rail with fuel injectors, disassembling and assembling

NOTE: The following list refers to items in Fig. 7 .

1. - Fuel injector insert -3 Nm

z Insert with locking fluid

z Locking fluid. See Parts Catalog.

2. - O-ring
z replace

z Coat with clean engine oil

3. - Fuel injector
z Cylinder 1 Fuel Injector - N30-

z Cylinder 2 Fuel Injector - N31-

z Cylinder 3 Fuel Injector - N32-

z Cylinder 4 Fuel Injector -N33-

4. - Supply hose
5. - Return hose
6. - Harness connector
z For injectors

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z 4x
7. - Socket head bolt -10 Nm
8. - Fuel pressure regulator
9. - O-ring
z replace

10. - O-ring
z replace

11. - Retaining clip

12. - Fuel distributor
13. - O-ring
z replace

z Coat with clean engine oil

14. - Retaining clip

z Make sure clip is correctly seated on fuel injector and fuel rail

15. - 10 Nm
16. - Throttle Valve Control Module -J338-
z With Throttle drive (power accelerator actuation) -G186-, Angle sensor -1- for throttle drive (power
accelerator actuation) -G187-, and Angle sensor -2- for throttle drive (power accelerator actuation)
-G188-
17. - Seal
z replace

18. - 10 Nm
19. - Intake Air Temperature (IAT) Sensor -G42-
20. - O-ring
z replace

21. - Intake manifold

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Fig. 7: Exploded View Of Intake Manifold And Fuel Rail With Fuel Injectors
Courtesy of AUDI OF AMERICA, INC.

Safety precautions

WARNING: Observe the following for all installations, especially in engine

compartment due to lack of room:

z Route lines of all types (for example, for fuel, hydraulic, EVAP
canister system, coolant and refrigerant, brake fluid, vacuum) and
electrical wiring so that the original path is followed.
z Watch for sufficient clearance to all moving or hot components.
z Fuel system is under pressure! Before opening system, place rags
around the connection point. Then release pressure by carefully
loosening connection.

To reduce the risk of personal injury and/or damage to the fuel injection and ignition system, always observe
the following:

z Do not touch or disconnect ignition wires when engine is running or turning at starting RPM.
z Only disconnect and reconnect wires for injection and ignition system, including test leads, when ignition
is turned off.
z If engine is to be cranked at starting RPM without starting
{ Remove fuses for voltage supply of ignition coils and for voltage supply of fuel injectors.

If special testing equipment is required during road test, note the following:
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Audi TT Coupe:

z Test equipment must always be secured to the rear seat and operated from there by a second person.

If test and measuring equipment is operated from the passenger seat, the person seated there could be injured in
the event of an accident involving deployment of the passenger -side airbag.

Audi TT Roadster:

z Deactivate the passenger-side airbag using the key switch in the glove compartment or via On Board
Diagnostic (OBD).
z Switch on passenger-side airbag after completing work.

Rules of cleanliness

When working on the fuel supply or fuel injection systems, the following "5 rules of cleanliness" should be
carefully observed:

z Thoroughly clean all connections and the surrounding area before disconnecting.
z Place parts that have been removed on a clean surface and cover. Use lint-free cloths only!
z Carefully cover over opened components or seal, if repairs are not performed immediately.
z Only install clean components:Only unpack replacement parts immediately prior to installation. Do not
use parts that have been stored loose (in tool boxes etc.)
z When the system is open:Do not work with compressed air if it can be avoided. Do not move vehicle
unless absolutely necessary.

Technical data

TECHNICAL DATA
Engine identification AMU ATC AWP BEA
Idle test(1)
Idle speed, RPM
Manual Transmission/Front Wheel 700...820 800...920 700...820 700...820
Drive (FWD)
Manual Transmission/All Wheel Drive 700...820 720...840 700...820 700...820
(AWD)
Automatic transmission/Front Wheel --- 640...760 --- ---
Drive (FWD)
Engine Control Module (ECM)(2)
Terminals at Engine Control Module 121 121 121 121
(ECM)
System identification Motronic Motronic Motronic Motronic
ME7.5 ME7.5 ME7.5 ME7.5
Part number Parts See Parts See Parts See Parts See Parts
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Catalog. Catalog. Catalog. Catalog.

Engine speed (RPM) limitation from approx. from approx. from approx. from approx.
6800 6800 6800 6800
(1) Not adjustable.
(2) Replacing, see ENGINE CONTROL MODULE (ECM)

CHECKING COMPONENTS

Oxygen sensor heater for oxygen sensor before Three Way Catalytic Converter (TWC), checking

NOTE: When servicing terminals in harness connector of Heated Oxygen Sensor

(HO2S), use only gold - plated terminals.

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of Heated Oxygen Sensor (HO2S) -G39- must be OK.
z Ignition switched off.

Engine codes AMU, ATC

z Disconnect 4-pin harness connector to Heated Oxygen Sensor (HO2S) -G39-.

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Fig. 8: Disconnecting 4-Pin Harness Connector To Heated Oxygen Sensor (HO2S) -G39- (Engine
Codes AMU, ATC)
Courtesy of AUDI OF AMERICA, INC.

z Set multimeter for resistance measurement and connect it to terminals 1 + 2 at connector for oxygen
sensor. Check oxygen sensor heater for continuity.

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Fig. 9: Identifying HO2S Connector Terminals (Engine Codes AMU, ATC)

Courtesy of AUDI OF AMERICA, INC.

Specified value: 1...5 (at room temperature)

Engine codes AWP, BEA

z Disconnect 6-pin harness connector to Heated Oxygen Sensor (HO2S) -G39-.

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Fig. 10: Identifying (HO2S) -G39- 6-Pin Harness Connector Terminals (Engine Codes AWP, BEA)
Courtesy of AUDI OF AMERICA, INC.

z Set multimeter for resistance measurement and connect it to terminals 3 + 4 at connector for oxygen
sensor. Check oxygen sensor heater for continuity.

Specified value: 2.5 to 10 ohm (at room temperature)

Continuation for all vehicles

If an open circuit is found in the oxygen sensor heater:

z Replace Heated Oxygen Sensor (HO2S) -G39-.

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If oxygen sensor heater has continuity:

z See CHECKING VOLTAGE SUPPLY AND WIRING .

Checking voltage supply and wiring

Engine codes AMU, ATC

z Set multimeter for voltage measurement and connect it to terminals 1 + 2 at connector to control module.
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Fig. 11: Identifying HO2S Harness Connector Terminals (Engine Codes AMU, ATC)
Courtesy of AUDI OF AMERICA, INC.

Engine codes AWP, BEA

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Fig. 12: Identifying HO2S Harness Connector Terminals (Engine Codes AWP, BEA)
Courtesy of AUDI OF AMERICA, INC.

z Set multimeter for voltage measurement and connect it to terminals 3 +4 at connector to control module.

Continuation for all vehicles

z Start engine, and let run at idle.

z Measure voltage supply

Specified value: approx. battery voltage, possibly fluctuating

If there is no voltage:

z Connect multimeter for voltage measurement to

Terminal 1 (Engine codes AMU, ATC)

Terminal 3 (engine codes AWP, BEA) of connector and engine Ground (GND).

z Operate starter briefly.

Specified value: approx. battery voltage

If there is no voltage again:

z Check wire connections from

Terminal 1 (Engine codes AMU, ATC)

Terminal 3 (engine codes AWP, BEA) to Fuel Pump (FP) Relay -J17-according to wiring diagram.

If voltage was approximately same as battery voltage:

z Switch ignition off.

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Engine Control Module (ECM) is not connected.

Engine codes AMU, ATC

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Fig. 13: Identifying HO2S Harness Connector Terminals (Engine Codes AMU, ATC)
Courtesy of AUDI OF AMERICA, INC.

z Check wire between test box and 4-pin connector for open circuit according to wiring diagram.

Terminal 2+socket 5

Wire resistance: max: 1.5 ohm

Engine codes AWP, BEA

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Fig. 14: Identifying HO2S Harness Connector Terminals (Engine Codes AWP, BEA)
Courtesy of AUDI OF AMERICA, INC.

z Check wire between test box and 6-pin connector for open circuit according to wiring diagram.

Terminal 4 + socket 5

Wire resistance: max: 1.5 ohm

Continuation for all vehicles

If no malfunctions are found in wires:

z Replace ECM. See REPLACING ENGINE CONTROL MODULE (ECM) .

Oxygen sensor heater for oxygen sensors behind Three Way Catalytic Converter (TWC), checking

NOTE: When servicing terminals in harness connector of Heated Oxygen Sensor

(HO2S), use only gold - plated terminals.

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram
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Test requirements

z The respective fuses of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130 -
must be OK.
z Ignition switched off.

Engine codes AMU, ATC

z Disconnect 4-pin harness connector to Oxygen Sensor (O2S) Behind Three Way Catalytic Converter
(TWC) -G130-.

Fig. 15: Disconnecting 4-Pin Harness Connector To O2S Behind Three Way Catalytic Converter -
G130 - (Engine Codes AMU, ATC)
Courtesy of AUDI OF AMERICA, INC.

z Set multimeter for resistance measurement and connect it to terminals 1 + 2 at connector for oxygen
sensor. Check oxygen sensor heater for continuity.

Specified value: 1 to 5 ohm (at room temperature)

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Fig. 16: Measuring Heater Resistance For O2S Behind Three Way Catalytic Converter -G130- (Engine
Codes AMU, ATC)
Courtesy of AUDI OF AMERICA, INC.

Engine codes AWP, BEA

z Disconnect 4-pin harness connector to Oxygen Sensor (O2S) Behind Three Way Catalytic Converter
(TWC) -G130-.
z Set multimeter for resistance measurement and connect it to terminals 1 + 2 at connector for oxygen
sensor. Check oxygen sensor heater for continuity.

Specified value: 6.4 to 7.5 ohm(at room temperature)

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Fig. 17: Identifying O2S G130 Behind TWC Connector Terminals (Engine Codes AWP, BEA)
Courtesy of AUDI OF AMERICA, INC.

Continuation for all vehicles

If an open circuit is found in the oxygen sensor heater:

z Replace Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-.

If oxygen sensor heater has continuity:

z Go to CHECKING VOLTAGE SUPPLY AND WIRING .

Checking voltage supply and wiring

z Set multimeter for voltage measurement and connect it to terminals 1 + 2 at connector to control module.

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Fig. 18: Identifying O2S Behind TWC Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Start engine, and let run at idle.

z Measure voltage supply

Specified value: oscillating between 0.0 and 12.0 V

If there is no voltage:

z Connect multimeter to terminal 1 of connector and engine Ground (GND) for voltage measurement.
z Operate starter briefly.

Specified value: approx. battery voltage

If there is no voltage again:

z Check wire connection from terminal 1 to Fuel Pump (FP) Relay -J17-according to wiring diagram.

If voltage was approximately same as battery voltage:

z Switch ignition off.

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
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TEST .

Engine Control Module (ECM) is not connected.

Fig. 19: Identifying O2S Behind TWC Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check wire between test box and 4-pin connector for open circuit according to wiring diagram.

Terminal 2+socket 63

Wire resistance: max: 1.5 ohm

If no malfunctions are found in wires:

z Replace ECM. See REPLACING ENGINE CONTROL MODULE (ECM) .

Mass Air Flow (MAF) sensor, checking

NOTE: Use only gold -plated terminals when servicing terminals in harness connector
of Mass Air Flow (MAF) sensor.

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram
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Test requirements

z The respective fuses of Mass Air Flow (MAF) Sensor -G70- must be OK.
z Fuel Pump (FP) Relay -J17- must be OK, check.
z Battery voltage must be at least 11.5 volts.
z All electrical consumers like, for example, lights and rear window heating must be switched off.
z Parking brake must be engaged or else daylight driving lights will be switched on.
z If vehicle is equipped with an A/C system, it must be switched off.
z Ground (GND) connections between engine and chassis must be OK.
z Coolant temperature must be at least 80°C. See DIAGNOSTIC MODE 1: CHECK MEASURED
VALUES ; PID 5, Coolant temperature.

Function test

z Connect diagnostic tester. See CONNECT DIAGNOSTIC TESTER .

z Start engine and let run at idle.
z Under address word 33, select "Diagnostic mode 1: Checking measured values."
z Select the measuring value "PID 16: Air flow quantity at Mass Air Flow (MAF) sensor".
z Check specified value of air flow quantity at Mass Air Flow (MAF) Sensor at idle:

PID 16: AIR FLOW QUANTITY AT MASS AIR FLOW (MAF) SENSOR
PID Diagnostic text Specified value:
16: Air flow quantity at Mass Air Flow (MAF) sensor 2.00 to 4.50 g/sec

z Engine running at idle

z End diagnosis and switch ignition off.

If specified value is obtained, but DTC memory has a DTC concerning Mass Air Flow (MAF) sensor:

z See VOLTAGE SUPPLY FOR MASS AIR FLOW (MAF) SENSOR, CHECKING .

If specified value is not obtained:

z See CHECKING SIGNAL AND GROUND WIRES OF MASS AIR FLOW (MAF) SENSOR .

Voltage supply for Mass Air Flow (MAF) sensor, checking

z Disconnect connector from Mass Air Flow (MAF) sensor.

z Connect multimeter to terminal 2 of connector and engine Ground (GND) for voltage measurement.

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Fig. 20: Identifying MAF Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Operate starter briefly.

Specified value: approx. battery voltage

If there is no voltage:

z Switch ignition off.

z Check wire connection from terminal 2 to Fuel Pump (FP) Relay -J17-according to wiring diagram.

If voltage supply and wires are OK:

z Switch ignition on.

z Connect multimeter to terminal 4 of connector and engine Ground (GND) for voltage measurement:

Specified value: 4.5 to 5.5 V

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Fig. 21: Identifying MAF Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

If there is no voltage:

z Switch ignition off.

z Check signal and ground wires. See CHECKING SIGNAL AND GROUND WIRES OF MASS AIR
FLOW (MAF) SENSOR .

Checking signal and Ground wires of Mass Air Flow (MAF) Sensor

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Engine Control Module (ECM) is not connected.

z Check wires between test box and 5-pin connector for open circuit according to wiring diagram.

Terminal 5 + socket 29

Terminal 4 + socket 53

Terminal 3 + socket 27

Wire resistance: max: 1.5 ohm

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Fig. 22: Identifying MAF Sensor Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: INFINITY ohm

If no DTCs are found in wires:

z Replace Mass Air Flow (MAF) Sensor -G70-

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

Throttle valve control module, checking

NOTE: Use only gold -plated terminals when servicing terminals in harness connector
of throttle valve control module.

Function

The throttle valve activation occurs via an electric motor (throttle drive) in the throttle valve control module. It
is activated by the Engine Control Module (ECM) according to specifications of the two sensors, Throttle
Position (TP) Sensor -G79- and Sender -2- for accelerator pedal position -G185-. See FUNCTION OF E-GAS
SYSTEM .

Components of Throttle Valve Control Module - J338-:

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z Throttle drive (power accelerator actuation) - G186-

z Angle sensor -1- for throttle drive (power accelerator actuation) -G187-
z Angle sensor -2- for throttle drive (power accelerator actuation) -G188-

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
z Battery voltage must be at least 11.5 volts.
z All electrical consumers like, for example, lights and rear window heating must be switched off.
z Parking brake must be engaged or else daylight driving lights will be switched on.
z If vehicle is equipped with an A/C system, it must be switched off.
z Ground (GND) connections between engine and chassis must be OK.
z Throttle valve must not be damaged or dirty.
z Coolant temperature must be at least 80°C. See DIAGNOSTIC MODE 1: CHECK MEASURED
VALUES ; PID 5, Coolant temperature.

Function test

z Connect diagnostic tester. See CONNECT DIAGNOSTIC TESTER .

z Switch ignition on.
z Under address word 33, select "Diagnostic mode 1: Checking measured values."
z Select the measuring value "PID 17: Throttle valve position (absolute)."
z Check specified value of throttle valve position (absolute) at idle stop:

PID 17: THROTTLE VALVE POSITION (ABSOLUTE) - IDLE

PID Diagnostic text Specified value:
17: Throttle valve position (absolute) approx. 3.0 %

z Idle stop

z Slowly depress accelerator pedal up to Wide Open Throttle (WOT) stop while observing the percentage
display.

The percentage display must increase uniformly.

z Check specified value of throttle valve position (absolute) at Wide Open Throttle (WOT) stop:

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PID 17: THROTTLE VALVE POSITION (ABSOLUTE) - WOT

PID Diagnostic text Specified value:
17: Throttle valve position 93.0...97.0 %
(absolute)

z Wide Open Throttle (WOT) stop

z End diagnosis and switch ignition off.

If specified values are not obtained:

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Engine Control Module (ECM) is not connected.

z Measure resistance of throttle valve drive between test box sockets 117 +118

Specified value: 1 to 5 ohm

If specified value is not obtained:

z Replace Throttle Valve Control Module -J338-.

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If specified value is obtained:

z Check voltage supply of throttle valve control module and wiring to control module. See CHECKING
VOLTAGE SUPPLY AND WIRING TO CONTROL MODULE .
z Check Throttle Position (TP) sensor. See THROTTLE POSITION (TP) SENSOR, CHECKING .

If voltage supply and wires are OK:

z See REPLACING ENGINE CONTROL MODULE (ECM) .

Checking voltage supply and wiring to control module

z Disconnect connector at throttle valve control module.

z Connect multimeter to terminals 2 + 6 of connector for voltage measurement.

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Fig. 23: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Switch ignition on.

Specified value: about 5 V

z Switch ignition off.

z Connect multimeter to terminal 2 of connector and Ground (GND) for voltage measurement.
z Switch ignition on.

Specified value: about 5 V

z Switch ignition off.

If specified values are not obtained:

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Engine Control Module (ECM) is not connected.

z Check for open circuits in wires between test box and connector according to wiring diagram:

Terminal 1+socket 92
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Terminal 2+socket 83

Terminal 3 + socket 117

Terminal 4 + socket 84

Terminal 5 + socket 118

Terminal 6 + socket 91

Wire resistance: max: 1.5 ohm

Fig. 24: Identifying Throttle Valve Control Module Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Also check wires for short circuit to each other.

z Also check wires for short circuits to B+ or Ground (GND).

If no malfunctions are found in wires:

z See VOLTAGE SUPPLY FOR ENGINE CONTROL MODULE (ECM), CHECKING .

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If no malfunctions are found in wires:

Engine Coolant Temperature (ECT) sensor, checking

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Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
z Parking brake must be engaged or else daylight driving lights will be switched on.
z Engine must be cold.

Function test

z Connect diagnostic tester. See CONNECT DIAGNOSTIC TESTER .

z Switch ignition on.
z Under address word 33, select "Diagnostic mode 1: Checking measured values."
z Select the measuring value "PID 05: Coolant temperature".
z Check specified value of coolant temperature:

PID 05: COOLANT TEMPERATURE

PID Diagnostic text Specified value:
05: Cooling fluid temperature approx. coolant temperature

If specified value is not obtained:

z Continue test according to the following table:

PID 05: TEST REFERENCE DATA

Indicated(1) Cause Continue testing
approx. -40 °C Open circuit or CONTINUATION FOR ALL VEHICLES
short circuit to B+
approx. 143 °C Short circuit to CHECKING WIRING
Ground (GND)
(1) If a temperature is indicated which differs greatly from ambient temperature of sensor, check sensor
wires for contact resistance.

If specified value is obtained:

z Start engine and let run at idle. The temperature should

climb uniformly

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NOTE: z The temperature increases in increments of 1.0°C.

z If the engine shows problems in certain temperature ranges and if the
temperature does not climb uniformly, the temperature signal is
intermittent and the sensor should be replaced.

Continuation of test if indication is approx. - 40 °C:

z Disconnect connector at coolant temperature sensor.

Coolant temperature sensor with square connector:

Fig. 25: Identifying ECT Sensor Connector Terminals (Square Connector)

Courtesy of AUDI OF AMERICA, INC.

z Bridge terminals 1 + 3 of connector using the respective adapter cables and observe the indication on
display.

Coolant temperature sensor with oval connector:

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Fig. 26: Identifying ECT Sensor Connector Terminals (Oval Connector)

Courtesy of AUDI OF AMERICA, INC.

z Bridge terminals 3 + 4 of connector using the respective adapter cables and observe the indication on
display.

Continuation for all vehicles

If indication jumps to approx. 143 °C:

z End diagnosis and switch ignition off.

z Replace Engine Coolant Temperature (ECT) Sensor -G62- with Engine Coolant Temperature (ECT)
Sensor -G2-.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If indication remains at approx. -40 °C:

z End diagnosis and switch ignition off.

z Check wires according to wiring diagram. See CHECKING WIRING .

Continuation of test if indication is approx. 143 °C:

z Disconnect 4-pin connector -1- from Engine Coolant Temperature (ECT) Sensor -G62- (-2-).

If indication jumps to approx. -40 °C:

z End diagnosis and switch ignition off.

z Replace Engine Coolant Temperature (ECT) Sensor -G62- with Engine Coolant Temperature (ECT)
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Sensor -G2-.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If indication remains at approx. 143°C:

z End diagnosis and switch ignition off.

z Check wires according to wiring diagram. See CHECKING WIRING .

Checking wiring

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Coolant temperature sensor with square connector:

z Check wires between test box and 4-pin connector for open circuit according to wiring diagram.

Terminal 1+socket 108

Terminal 3 + socket 93

Wire resistance: max: 1.5ohm

Fig. 27: Identifying ECT Sensor Harness Connector Terminals (Square Connector)
Courtesy of AUDI OF AMERICA, INC.

Coolant temperature sensor with oval connector:

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z Check wires between test box and 4-pin connector for open circuit according to wiring diagram.

Terminal 3 + socket 108

Terminal 4 + socket 93

Wire resistance: max: 1.5ohm

Fig. 28: Identifying ECT Sensor Harness Connector Terminals (Oval Connector)
Courtesy of AUDI OF AMERICA, INC.

Continuation for all vehicles

z Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: INFINITY ohm

If no malfunctions are found in wires:

Coolant temperature sensor with square connector:

z Connect multimeter between terminal 1 and 3 of sensor for resistance measurement.

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Fig. 29: Identifying ECT Sensor Connector Terminals (Square Connector)

Courtesy of AUDI OF AMERICA, INC.

Coolant temperature sensor with oval connector:

z Connect multimeter between terminal 3 and 4 of sensor for resistance measurement.

Fig. 30: Identifying ECT Sensor Connector Terminals (Oval Connector)

Courtesy of AUDI OF AMERICA, INC.

Continuation for all vehicles

Range A displays resistance values for the temperature range of 0 to 50°C, range B displays resistance values
for the temperature range of 50 to 100 °C.

Read-out examples:

z 30 °C corresponds to a resistance of 1500 to 2000 ohm

z 80 °C corresponds to a resistance of 275 to 375 ohm
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Fig. 31: ECT Sensor Temperature Versus Resistance Values Graph

Courtesy of AUDI OF AMERICA, INC.

If specified value is not obtained:

z Replace Engine Coolant Temperature (ECT) Sensor -G62- with Engine Coolant Temperature (ECT)
Sensor -G2-.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If no malfunctions are detected in the wires and the resistance values are OK:

z Replace Motronic Engine Control Module (ECM) -J220-. See REPLACING ENGINE CONTROL
MODULE (ECM) .

Intake Air Temperature (IAT) sensor, checking

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

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z VAG1594 connector test kit

z Wiring diagram
z Chilling spray (commercially available)

Test requirements

z The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
z Parking brake must be engaged or else daylight driving lights will be switched on.

Function test

z Connect diagnostic tester. See CONNECT DIAGNOSTIC TESTER .

z Switch ignition on.
z Under address word 33, select "Diagnostic mode 1: Checking measured values."
z Select the measuring value "PID 15: Intake air temperature".
z Check specified value of intake air temperature:

PID 15: INTAKE AIR TEMPERATURE

PID Diagnostic text Specified value:
15: Intake Air approx. ambient
Temperature (IAT) temperature

If specified value is not obtained:

z Continue test according to the following table:

PID 15: TEST REFERENCE DATA

Indicated(1) Cause Continue testing
approx. -40 °C Open circuit or short circuit to B+ CHECKING WIRING
approx. 143 °C Short circuit to Ground (GND) CHECKING WIRING
(1) If a temperature is indicated which is below the ambient temperature of sensor, first check sensor
wires for contact resistance. Note that while the vehicle is standing still the sensor might warm up
due to radiant heat.

If specified value is obtained:

z Remove Intake Air Temperature (IAT) Sensor - G42-. Plug connector back in.
z Remember the intake air temperature value.
z Spray the sensor with commercially available chilling spray while observing the temperature value. The
temperature should

decrease.

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z End diagnosis and switch ignition off.

If the intake air temperature does not drop:

z Replace Intake Air Temperature (IAT) Sensor - G42-.

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

Continuation of test if indication is approx. - 40°C:

z Disconnect connector -1- from Intake Air Temperature (IAT) Sensor -G42- -2-.

Fig. 32: Disconnecting Connector -1- From Intake Air Temperature (IAT) Sensor -G42-
Courtesy of AUDI OF AMERICA, INC.

z Bridge terminals 1 + 2 of connector using the respective adapter cables while observing the indication on
display.

If indication jumps to approx. 143°C:

z End diagnosis and switch ignition off.

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z Replace Intake Air Temperature (IAT) Sensor -G42-.

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If indication remains at approx. -40°C:

z End diagnosis and switch ignition off.

z Check wires according to wiring diagram. See CHECKING WIRING .

Continuation of test if indication is approx. 143°C:

z Disconnect connector -1- from Intake Air Temperature (IAT) Sensor -G42- -2-.

Fig. 33: Disconnecting Connector -1- From Intake Air Temperature (IAT) Sensor -G42-
Courtesy of AUDI OF AMERICA, INC.

If indication jumps to approx. -40°C:

z End diagnosis and switch ignition off.

z Replace Intake Air Temperature (IAT) Sensor -G42-.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If indication remains at approx. 143°C:

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z End diagnosis and switch ignition off.

z Check wires according to wiring diagram. See CHECKING WIRING .

Checking wiring

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Fig. 34: Identifying Intake Air Temperature (IAT) Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Check wires between test box and 2-pin connector for open circuit according to wiring diagram.

Terminal 1+socket 85

Terminal 2+socket 108

Wire resistance: max: 1.5 ohm

z Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.
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Specified value: INFINITY ohm

If no malfunctions are found in wire:

Fig. 35: Measuring Intake Air Temperature (IAT) Sensor Resistance

Courtesy of AUDI OF AMERICA, INC.

z Measure resistance at Intake Air Temperature (IAT) Sensor -G42-.

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Fig. 36: IAT Sensor Temperature Versus Resistance Graph

Courtesy of AUDI OF AMERICA, INC.

Range A displays resistance values for the temperature range of 0...50 °C, range B displays resistance values for
the temperature range of 50...100 °C.

Read-out examples:

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z 30 °C is in range A and corresponds to a resistance of 1.5 to 2.0 kohm

z 80 °C is in range B and corresponds to a resistance of 275 to 375 ohm

If specified value is not obtained:

z Replace Intake Air Temperature (IAT) Sensor -G42-.

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If no malfunctions are detected in the wires and the resistance values are OK:

z Replace Motronic Engine Control Module (ECM) -J220-. See REPLACING ENGINE CONTROL
MODULE (ECM) .

Check Engine Speed (RPM) sensor

Function

The Engine Speed (RPM) Sensor -G28- detects engine speed and reference marks. Without an engine speed
signal, the engine will not start. If the engine speed signal fails while the engine is running, the engine will stop
immediately.

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test sequence

z Measure sensor resistance between terminals 2 + 3 at connector to sensor.

Specified value: 730...1000 INFINITY ohm

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Fig. 37: Identifying Engine Speed (RPM) Sensor Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check sensor for short circuit between terminals 1 + 2 as well as 1 + 3.

Specified value: INIFINITY ohm

If specified values are not obtained:

z Replace Engine Speed (RPM) Sensor -G28-.

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

If no DTC is found on sensor:

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .
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z Check wires between test box and 3-pin connector for open circuit according to wiring diagram.

Terminal 1+socket 108

Terminal 2+socket 90

Terminal 3 + socket 82

Wire resistance: max: 1.5

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Fig. 38: Identifying Engine Speed (RPM) Sensor Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.
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z Also check wires for short circuit to each other, to vehicle Ground (GND) and to B+.

Specified value: INIFINITY ohm

If no malfunctions are found in wires:

z Remove sensor and check sensor wheel for secure fit, damage, and run -out.

NOTE: There is a larger -sized gap on the sensor wheel. This gap is the reference mark
and does not mean that the sensor wheel is damaged.

If nothing seems to be wrong with the sensor wheel:

z Replace Motronic Engine Control Module (ECM) -J220-. See REPLACING ENGINE CONTROL
MODULE (ECM) .

Check fuel injectors

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1527 voltage test lamp
z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of fuel injectors (Cylinder 1 Fuel Injector -N30-to Cylinder 4 Fuel Injector -N33-)
must be OK.
z Fuel Pump (FP) Relay -J17- must be OK, check.
z Battery voltage must be at least 11.5 volts.
z All electrical consumers like, for example, lights and rear window heating must be switched off.
z Parking brake must be engaged or else daylight driving lights will be switched on.
z For vehicles with automatic transmission, selector lever must be in position -P- or -N-.
z If vehicle is equipped with an A/C system, it must be switched off.
z Ground (GND) connections between engine and chassis must be OK.
z Engine speed (RPM) sensor must be OK. For checking, CHECK ENGINE SPEED (RPM) SENSOR .
z Ignition switched off.

Test sequence

Resistance values of fuel injectors, checking

z Test resistance of fuel injectors between terminals.

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Specified value: 12 to 13 °(at room temperature)

Fig. 39: Testing Resistance Of Fuel Injectors Between Terminals

Courtesy of AUDI OF AMERICA, INC.

NOTE: Resistance value is valid at approx. 20 °C. At higher temperatures, resistance

value increases.

If specified value is not obtained:

z Replace faulty fuel injector.

Note the following when installing the fuel injectors:

z Replace O-rings on all fuel injectors and wet them slightly with clean motor oil.
z Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining
clips.
z Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to
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press it in.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

Checking voltage supply

z Connect diode test lamp to connector of fuel injector to be tested terminal 1 and Ground (GND).

Fig. 40: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Operate starter and test voltage supply for fuel injector.

LED must light up.

z Switch ignition off.

If LED does not light up:

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z Check wire between 2-pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit
according to wiring diagram.

Wire resistance: max: 1.5 ohm

Activation and voltage supply, checking

z Connect diode test lamp to the connector terminals of the fuel injector to be checked.

Fig. 41: Connecting Diode Test Lamp To Connector Terminals Of Fuel Injector
Courtesy of AUDI OF AMERICA, INC.

z Operate starter and test activation of fuel injector.

LED should flicker.

z Switch ignition off.

If LED does not flicker:

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z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Fig. 42: Identifying Fuel Injector Harness Connector Terminals

Courtesy of AUDI OF AMERICA, INC.

z Check wires between test box and 2-pin connector for open circuit according to wiring diagram.

Wire resistance: max: 1.5 ohm

FUEL INJECTOR CIRCUIT TEST - OPENS

Component Connector Test box
Cylinder 1 Fuel Injector -N30- Terminal 2 Socket 96
Cylinder 2 Fuel Injector -N31- Terminal 2 Socket 89
Cylinder 3 Fuel Injector -N32- Terminal 2 Socket 97
Cylinder 4 Fuel Injector -N33- Terminal 2 Socket 88

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z Also check wires for short circuit to B+ and Ground (GND).

Specified value: INFINITY ohm

z Replace Motronic Engine Control Module (ECM) -J220-. See REPLACING ENGINE CONTROL
MODULE (ECM) .

Checking fuel injectors for injection quantity and proper seal

Recommended special tools and equipment

z VAG1348/3A remote control with VAG1348/3-2 adapter cable

z V.A.G 1602 tester for quantity of injected fuel

Without illustration:

z VAG1594A connector test kit

Fig. 43: Identifying Special Tool

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Courtesy of AUDI OF AMERICA, INC.

Test requirement

z Fuel pressure must be OK. See FUEL PRESSURE REGULATOR AND RESIDUAL PRESSURE,
CHECKING .

WARNING: Fuel system is under pressure! Before opening system, place rags
around the connection point. Then release pressure by carefully
loosening connection.

Test sequence

z Disconnect fuel injector connectors.

z Remove mounting bolts from fuel distributor.
z Then remove the fuel distributor completely.
z Disconnect vacuum hose from fuel pressure regulator.
z Lift fuel rail with fuel injectors off intake manifold and support it.
z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

NOTE: The only purpose of this step is to allow the Fuel Pump (FP) to run with the
engine at standstill.

z Switch ignition on.

Checking Proper Seal

z Bridge sockets 1 + 65 of test box with the respective adapter cables.

Fuel Pump (FP) must run.

z Check proper seal of fuel injectors (visual inspection). With Fuel Pump (FP) running, only 1 to 2 drops
per minute should escape from each valve.
z Disconnect connection between test box sockets.
z Switch ignition off.

If fuel loss is greater:

z Replace faulty fuel injector.

Note the following when installing the fuel injectors:

z Replace O -rings on all fuel injectors and wet them slightly with clean motor oil.

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z Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining
clips.
z Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to
press it in.
{ Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4:
RESET/ERASE DIAGNOSTIC DATA .
{ Generate readiness code. See READINESS CODE, GENERATING .

Checking Injection Quantity

z Insert a fuel injector to be tested into a measuring tube of VAG1602 tester for fuel injection quantity.
z Using respective adapter cables, connect one terminal of fuel injector to be checked to engine Ground
(GND).
z Use adapter cable to connect second terminal of fuel injector to VAG1348/3 remote control with
VAG1348/3 -2 adapter cable.

Fig. 44: Connecting Fuel Injector To VAG1348/3 Remote Control

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Courtesy of AUDI OF AMERICA, INC.

z Connect alligator clip to B+.

z Switch ignition on.
z Bridge sockets 1 + 65 of test box with the respective adapter cables.

Fuel Pump (FP) must run.

z Operate VAG1348/3 remote control for 30 seconds.

z Repeat test on other fuel injectors. Use new graduated measuring glasses for this.

NOTE: Also check spray pattern when checking injection quantity. Spray pattern
must be the same for all injectors

z After all fuel injectors have been activated, place graduated measuring glasses on a level surface and
compare quantity of injected fuel.

Specified value: 165 to 193 ml per injector

z Disconnect connection between test box sockets.

z Switch ignition off.

If the measured value of one or more fuel injectors is below or above the indicated specified value:

z Replace faulty fuel injector.

Installation of fuel injectors is the same in reverse order. Note the following:

z Replace O -rings on all fuel injectors and wet them slightly with clean motor oil.
z Insert fuel injectors into fuel rail perpendicular and in the right position, and secure them with retaining
clips.
z Position fuel distributor with secured fuel injectors on intake manifold and apply uniform pressure to
press it in.
{ Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4:
RESET/ERASE DIAGNOSTIC DATA .
{ Generate readiness code. See READINESS CODE, GENERATING .

Fuel pressure regulator and residual pressure, checking

The fuel pressure regulator controls the fuel pressure as a function of the Manifold Absolute Pressure (MAP).

The specified value for this test is dependent on the working pressure of the Fuel Pump (FP). This is

about 4.0 bar positive pressure

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Special tools and equipment

z VAG1318 pressure gauge

Fig. 45: Identifying VAG1318 Pressure Gauge

Courtesy of AUDI OF AMERICA, INC.

z VAG1318/6+7 adapter

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Fig. 46: Identifying VAG1318/6+7 Adapter

Courtesy of AUDI OF AMERICA, INC.

z VAG1318/17 (2x)

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Fig. 47: Identifying VAG1318/17

Courtesy of AUDI OF AMERICA, INC.

WARNING: Fuel system is under pressure! Before opening system, place rags
around the connection point. Then release pressure by carefully
loosening connection.

Test sequence

z Remove engine cover (arrows).

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Fig. 48: Removing Engine Cover

Courtesy of AUDI OF AMERICA, INC.

z Remove bolt -1- and remove reservoir cover (arrow).

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Fig. 49: Removing Bolt -1- And Remove Reservoir Cover

Courtesy of AUDI OF AMERICA, INC.

z Open fuel filler flap briefly (pressure release).

z Disconnect fuel supply line -1- by pressing release button.

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Fig. 50: Disconnecting Fuel Supply Line -1- By Pressing Release Button
Courtesy of AUDI OF AMERICA, INC.

z Connect VAG1318 using adapters 1318/7 and 1318/17 (2 pieces) at supply line.

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Fig. 51: Connecting VAG1318 Using Adapters 1318/7 And 1318/17 (2 Pieces) At Supply Line
Courtesy of AUDI OF AMERICA, INC.

z Open shut-off valve of pressure gauge. The lever points in the direction of flow.
z Start engine and let run at idle.
z Measure fuel pressure.
z Specified value: about 2.5 bar positive pressure

z Disconnect vacuum hose at fuel pressure regulator.

z Fuel pressure must rise to about 3.0 bar positive pressure.

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Fig. 52: Disconnecting Vacuum Hose At Fuel Pressure Regulator

Courtesy of AUDI OF AMERICA, INC.

z Switch ignition off.

z Check for proper seal and residual pressure by observing pressure drop on pressure gauge.
z After 10 minutes, there must be at least 1.5 bar positive pressure

If residual pressure sinks below 1.5 bar positive pressure:

z Start engine and let run at idle.

z Wait until pressure has risen, and then switch off ignition. Simultaneously close shut -off valve of
VAG1318 pressure gauge (lever perpendicular to direction of flow -arrow-).

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Fig. 53: Closing Shut -Off Valve Of VAG1318 Pressure Gauge

Courtesy of AUDI OF AMERICA, INC.

z Observe pressure drop on pressure gauge.

If pressure does not drop now:

z Test check-valve on Fuel Pump (FP).

If pressure drops again:

z Open shut-off valve of VAG1318 pressure gauge (lever in direction of flow).

z Start engine and let run at idle.
z Wait until pressure has risen, and then switch off ignition. Simultaneously clamp return line (with blue
marking) completely closed.

If pressure does not drop now:

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z Replace fuel pressure regulator

If pressure drops again:

z Check line connections, O-rings at fuel distributor and fuel injectors for proper seal.
z Check whether pressure gauge is properly sealed.

NOTE: Before disconnecting pressure gauge, release fuel pressure by opening shut -
off valve. Hold a container in front of connection for this.

Checking intake system for leaks (unmetered air)

Checking with engine leak detection spray

Recommended special tools and equipment

z Engine leak detection spray G 001 800 A1

Test requirement

z Coolant temperature must be at least 80°C. See DIAGNOSTIC MODE 1: CHECK MEASURED
VALUES ; PID 5, Coolant temperature.

Test sequence

NOTE: z The negative pressure in the intake system sucks in the leak detection
spray with the unmetered air. Leak detection spray decreases ignition
quality and performance of the fuel mixture. This causes a drop in engine
speed and changes the value produced by the Heated Oxygen Sensor
(HO2S).
z It is absolutely necessary to follow the safety precautions listed on the
can.

z Connect diagnostic tester. See CONNECT DIAGNOSTIC TESTER .

z Start engine and let run at idle.
z Under address word 33, select "Diagnostic mode 1: Checking measured values."
z Select the following measured values and check the specified values at idle:

DIAGNOSTIC MODE 1: CHECKING MEASURED VALUES

PID Diagnostic text Specified value:
06: Short time gasoline-air ratio bank 1 -10.00...10.00 %
12: Engine rotations per minute (RPM) 700 to 920 RPM

z Spray intake system parts with engine leak detection spray in a systematic manner.
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If engine speed drops or if the short-term gasoline-air ratio changes:

z End diagnosis and switch ignition off.

z Check sprayed part of intake system for leaks, and eliminate the error.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

FUNCTION TESTS

Oxygen Sensor (O2S) and oxygen sensor control before Three Way Catalytic Converter (TWC), checking

NOTE: When servicing terminals in harness connector of Heated Oxygen Sensor

(HO2S), use only gold - plated terminals.

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of Heated Oxygen Sensor (HO2S) -G39- must be OK.
z Battery voltage must be at least 11.5 volts.
z All electrical consumers like, for example, lights and rear window heating must be switched off.
z Parking brake must be engaged or else daylight driving lights will be switched on.
z If vehicle is equipped with an A/C system, it must be switched off.
z Ground (GND) connections between engine and chassis must be OK.
z Exhaust system must be properly sealed between catalytic converter and cylinder head.
z Oxygen sensor heaters for oxygen sensors before catalytic converter must be OK. See CHECKING
COMPONENTS .

Checking primary voltage

Engine codes AMU, ATC

z Disconnect 4-pin harness connector to Heated Oxygen Sensor (HO2S) -G39-.

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Fig. 54: Disconnecting 4-Pin Harness Connector To Heated Oxygen Sensor (HO2S) -G39-
Courtesy of AUDI OF AMERICA, INC.

z Use adapter cables from V.A.G 1594 to connect multimeter to terminals 3 + 4 (ECM connector) for
voltage measurement.

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Fig. 55: Identifying HO2S G39 Harness Connector Terminals (Engine codes AMU, ATC)
Courtesy of AUDI OF AMERICA, INC.

z Start engine and measure primary voltage.

Specified value: 0.40 to 0.50 Volts

z Switch ignition off.

Engine codes AWP, BEA

z Disconnect 6-pin harness connector to Heated Oxygen Sensor (HO2S) -G39-.

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Fig. 56: Identifying HO2S G26 6-Pin Harness Connector Terminals (Engine Codes AWP, BEA)
Courtesy of AUDI OF AMERICA, INC.

z Connect multimeter between terminal 1 and 5 for voltage measurement.

z Switch on ignition and measure primary voltage.

Specified value: 0.40 to 0.50 Volts

z Switch ignition off.

Continuation for all vehicles

If specified value is not obtained:

z Test oxygen sensor wires. SeeCHECKING OXYGEN SENSOR WIRES .

If specified value is obtained:

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z Replace Heated Oxygen Sensor (HO2S) -G39-.

z - Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4:
RESET/ERASE DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

Checking oxygen sensor wires

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .

Engine codes AMU, ATC

z Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit
according to wiring diagram.

Wire resistance: max: 1.5 ohm

Fig. 57: Identifying HO2S 4-Pin Harness Connector Terminals (Engine Codes AMU, ATC)
Courtesy of AUDI OF AMERICA, INC.
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HO2S CIRCUIT TEST - ENGINE CODES AMU, ATC

Component Connector Test box
Bank 1 sensor 1 Terminal 3 Socket 51
Terminal 4 Socket 70

Engine codes AWP, BEA

z Check wires between test box and 6-pin connector to Engine Control Module (ECM) for open circuit
according to wiring diagram.

Fig. 58: Identifying HO2S 6-Pin Harness Connector Terminals (Engine Codes AWP, BEA)
Courtesy of AUDI OF AMERICA, INC.

Wire resistance: max: 1.5ohm

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HO2S CIRCUIT TEST - ENGINE CODES AWP, BEA

Component Connector Test box
Bank 1 sensor 1 Terminal 1 Socket 70
Terminal 2 Socket 71
Terminal 5 Socket 51
Terminal 6 Socket 52

Continuation for all vehicles

z Also check wires for short circuit to B+ and Ground (GND).

Specified value: INFINITY ohm

If no malfunctions are found in wires:

z Replace Motronic Engine Control Module (ECM) -J220-. See REPLACING ENGINE CONTROL
MODULE (ECM) .

Oxygen Sensor and oxygen sensor control behind Three Way Catalytic Converter (TWC), checking

NOTE: When servicing terminals in harness connector of Heated Oxygen Sensor

(HO2S), use only gold-plated terminals.

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130 -
must be OK.
z Battery voltage must be at least 11.5 volts.
z All electrical consumers like, for example, lights and rear window heating must be switched off.
z Parking brake must be engaged or else daylight driving lights will be switched on.
z If vehicle is equipped with an A/C system, it must be switched off.
z Ground (GND) connections between engine and chassis must be OK.
z Exhaust system must be properly sealed between catalytic converter and cylinder head.
z Coolant temperature must be at least 80 degrees C. See DIAGNOSTIC MODE 1: CHECK
MEASURED VALUES ; PID 5, Coolant temperature.
z Oxygen sensor heater for oxygen sensors behind catalytic converter must be OK. See OXYGEN
SENSOR HEATER FOR OXYGEN SENSORS BEHIND THREE WAY CATALYTIC

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CONVERTER (TWC), CHECKING .

Function test

z Select the following output of oxygen sensor signals and check whether the specified values are being
reached. See DIAGNOSTIC MODE 5: CHECK OUTPUT OF OXYGEN SENSOR SIGNALS .
z Check the specified values of the output of oxygen sensor signals at idle:

DIAGNOSTIC MODE 5: OXYGEN SENSOR SIGNAL VALUES

Specified value:
Test-ID Diagnostic text min. max.
07: Minimum voltage at sensor for test cycle 0V 0.650 V

Bank 1 sensor 2
z

08: Maximum voltage at sensor for test cycle 0.550V 1.050 V

z Bank 1 sensor 2

If specified values are obtained:

z End diagnosis and switch ignition off.

If specified values are not obtained:

z End diagnosis and let engine continue to run at idle. See CHECKING PRIMARY VOLTAGE .

Checking primary voltage

z Disconnect 4-pin harness connector to Oxygen Sensor (O2S) Behind Three Way Catalytic Converter
(TWC) -G130-.
z Use adapter cables from VAG1594 to connect multimeter to terminals 3 + 4 (Motronic ECM connector)
for voltage measurement.

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Fig. 59: Identifying HO2S G130 Behind TWC, 4-Pin Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

z Start engine and measure primary voltage.

Specified value: 0.40 to 0.50 Volts

z Switch ignition off.

If specified value is not obtained:

z Test oxygen sensor wires. See CHECKING OXYGEN SENSOR WIRES .

z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .

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z Generate readiness code. See READINESS CODE, GENERATING .

If specified value is obtained:

z Replace Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-.

Checking oxygen sensor wires

z Check wires between test box and 4-pin connector to Engine Control Module (ECM) for open circuit
according to wiring diagram.

Wire resistance: max: 1.5 ohm

Fig. 60: Identifying HO2S G130 Behind TWC, 4-Pin Harness Connector Terminals
Courtesy of AUDI OF AMERICA, INC.

HO2S BEHIND TWC CIRCUIT TEST - OPENS

Component Connector Test box
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Bank 1 sensor 2 Terminal 3 Socket 68

Terminal 4 Socket 69

Continuation for all vehicles

z Also check wires for short circuit to B+ and Ground (GND).

Specified value: INFINITY ohm

If no malfunctions are found in wires:

z Replace Motronic Engine Control Module (ECM) -J220-. See REPLACING ENGINE CONTROL
MODULE (ECM) .

ENGINE CONTROL MODULE (ECM)

Function

The Engine Control Module (ECM) controls fuel injection, the throttle valve control module, oxygen sensor
control, ignition, knock control, EVAP canister purge regulator valve, engine speed limitation via fuel injectors
and fuel pump relay, camshaft adjustment and On Board Diagnostic (OBD).

Voltage supply for Engine Control Module (ECM), checking

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK.
z Fuel Pump (FP) Relay -J17- must be OK, check.
z Generator (GEN) must be OK, checking.
z Battery voltage must be at least 11.5 volts.
z All electrical consumers like, for example, lights and rear window heating must be switched off.
z Parking brake must be engaged or else daylight driving lights will be switched on.
z If vehicle is equipped with an A/C system, it must be switched off.
z Ground (GND) connections between engine and chassis must be OK.

Test sequence

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .
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Checking voltage supply terminal 30

z Measure voltage supply between sockets 1 + 62 and 2 + 62 of test box.

Specified value: at least 11.5 V

If specified value is not obtained:

z Check wire connections to relay carrier and Ground (GND) connection of Engine Control Module (ECM)
according to wiring diagram.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

Checking voltage supply terminal 15

z Measure voltage supply between sockets 1 + 3 and 2 + 3 of test box.

z Switch ignition on.

Specified value: at least 11.5 V

If specified value is not obtained:

z Check wire connections to relay carrier and Ground (GND) connection of Engine Control Module (ECM)
according to wiring diagram.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

Replacing Engine Control Module (ECM)

NOTE: To achieve optimal anti-theft protection for the vehicle, an anti-theft immobilizer
was installed. The anti-theft immobilizer is a system for enabling/locking the
Engine Control Module (ECM) via the W-wire.
So that this system cannot be circumvented, it is necessary to perform
adaptation of the anti -theft immobilizer using the VAS 5052 in the On Board
Diagnostic (OBD) function.
The great availability of equipment options makes adaptation of the Engine
Control Module (ECM) necessary (e.g. cruise control system). This "writing"
function is not possible with the generic scan tool, therefore it is necessary to
use the VAS 5052 in On Board Diagnostic (OBD) function for this purpose.

z Procedure to replace Engine Control Module (ECM):

See MOTRONIC INJECTION SYSTEM, SERVICING (engine codes AMU and

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BEA), or INJECTION SYSTEM, SERVICING (engine code AWP), or

MOTRONIC MULTIPORT FUEL INJECTION AND IGNITION SYSTEM,
REPAIRING (engine code ATC).

z Generate readiness code. See READINESS CODE, GENERATING .

CHECKING ADDITIONAL SIGNALS

Checking speed signal

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

Test requirements

z The respective fuses of Motronic Engine Control Module (ECM) -J220- must be OK:
z Battery voltage must be at least 11.5 volts.
z Speedometer -G21- must be OK.

Test sequence

NOTE: To test speed signal, vehicle must be driven. Doing this requires a second
person.

WARNING: Secure Scan Tool (ST) on the rear seat and have it operated from there by
second technician.

z Connect diagnostic tester. See CONNECT DIAGNOSTIC TESTER .

z Start engine and let run at idle.
z Under address word 33, select "Diagnostic mode 1: Checking measured values."
z Select the measuring value "PID 13: Vehicle speed".
z Perform a road test, and have the 2nd person observe the indication on the display.
z Check specified value of the vehicle speed:

PID 13: VEHICLE SPEED

PID Diagnostic text Specified value:
13: Vehicle speed approx. vehicle speed

z End diagnosis and switch ignition off.

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If no speed is indicated:

z Connect test box to control module wiring harness. See CONNECT TEST BOX FOR WIRING
TEST .
z To measure voltage, connect multimeter between sockets 3 (terminal 15) +54 (speed signal) of test box.
z Jack up front left wheel.
z Switch ignition on.
z Rotate front wheel, and observe voltage indicated while doing so.

Specified value: 0.0 to at least 4.0 V, fluctuating

NOTE: The right front wheel must not turn during this, hold it steady if necessary.

If indicated voltage does not oscillate:

z Remove instrument cluster:

See INSTRUMENTS .

z Check wire connection from Engine Control Module (ECM) to Speedometer -G21- according to wiring
diagram.
z Erase DTC memory of Engine Control Module (ECM). See DIAGNOSTIC MODE 4: RESET/ERASE
DIAGNOSTIC DATA .
z Generate readiness code. See READINESS CODE, GENERATING .

Terminal resistance for CAN-Bus, checking

Function

The Engine Control Module (ECM) communicates with all databus-capable control modules via a CAN
databus.

These databus-capable control modules are connected via two data bus wires which are twisted together
(CAN_High and CAN_Low), and exchange information (messages). Missing information on the databus is
recognized as a malfunction and stored.

Trouble-free operation of the CAN-Bus requires that it have a terminal resistance. This central terminal resistor
is located in the Engine Control Module (ECM).

Recommended special tools and equipment

z VAG1526 multimeter or VAG1715 multimeter

z VAG1594 connector test kit
z Wiring diagram

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Test requirements

z DTC "P0600 Serial Communication Link" was detected by the Engine Control Module (ECM). See
DIAGNOSTIC MODE 3: CHECK DTC MEMORY .
z Ignition switched off.

Test sequence

z Connect test box to Engine Control Module (ECM). See CONNECT TEST BOX FOR WIRING
TEST . During this, wiring harness to Engine Control Module (ECM) is NOT connected.
z Check the central termination resistor in the Engine Control Module (ECM):
z To do this, measure resistance between test box

socket 58 + 60:

Specified value: 60...72

If resistance value is not in expected range:

z Replace Motronic Engine Control Module (ECM) -J220-. See REPLACING ENGINE CONTROL
MODULE (ECM) .

If resistance value is in expected range:

z Disconnect test box from Engine Control Module (ECM).

z Connect test box to control module wiring harness.
z Check CAN data bus wires for short circuit to each other:
z To do this, perform a resistance measurement between test box sockets 58 + 60:

Specified value: INIFINITY ohm

If specified value is obtained (wires have no shorts):

z Eliminate error in wires according to wiring diagram.

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