Service

Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo)
Engine ID AGU

Edition 11.1996
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Service Department. Technical Information

 Service
List of Workshop Manual Repair GroupsList of Workshop Manual
Repair GroupsList of Workshop Manual Repair Groups
Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo)

Repair Group
01 - Self-diagnosis
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
24 - Mixture preparation, Injection
28 - Ignition system

Technical information should always be available to the foremen and mechanics, because their careful
and constant adherence to the instructions is essential to ensure vehicle road-worthiness and safety. In
addition, the normal basic safety precautions for working on motor vehicles must, as a matter of course,
be observed.

All rights reserved.

No reproduction without prior agreement from publisher.

Copyright © 2010 Audi AG, Ingolstadt A0050006620

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Contents

01 - Self-diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1 Self-diagnosis for the Motronic system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.1 Self-diagnosis for the Motronic system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.2 Technical data for the self-diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
1.3 Connecting the V.A.G 1551 fault reader and selecting the engine electronics control unit . . 2
1.4 Interrogating and erasing fault memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.5 Fault table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.6 Final control diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
1.7 Basic setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
1.8 Encoding the control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
1.9 Reading measured value block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
1.10 Reading measured value block: Display Groups 00 to 10 . . . . . . . . . . . . . . . . . . . . . . . . . .26
1.11 Reading measured value block: Display Groups 08 to 99 . . . . . . . . . . . . . . . . . . . . . . . . . .32

24 - Mixture preparation, Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

1 Repairing the Motronic fuel injection system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
1.1 Repairing the Motronic fuel injection system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
1.2 Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
1.3 Rules for cleanliness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
1.4 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
1.5 Overview of fitting locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
1.6 Wiring and component check with test box V.A.G 1598/22 . . . . . . . . . . . . . . . . . . . . . . . . . .47
1.7 Replacing the engine control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
1.8 Checking idling speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
1.9 Checking fuel pressure regulator and holding pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
1.10 Checking injection quantity, leak tightness and spray pattern of injectors . . . . . . . . . . . . . .52
1.11 Checking the injectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
1.12 Checking fuel pump relay and actuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
1.13 Checking the air mass meter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
2 Checking the boost pressure system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
2.1 Checking the boost pressure system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
2.2 Checking the boost pressure control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
2.3 Checking solenoid valve for boost pressure control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
2.4 Checking altitude sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
3 Checking the lambda control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
3.1 Checking the lambda control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
3.2 Poor performance after cold start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
3.3 byChecking
Protected operation
copyright. Copying for private.or. commercial
. . . . . . purposes,
. . . . . .in. part
. . or
. .in. whole,
. . . .is.not
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
3.4with respect to the correctness of information in this document. Copyright by AUDI AG. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .68
Checking lambda probe heating . . . . . . . . . . . . . . . .
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

3.5 Checking lambda probe signal line and actuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

3.6 Removing and installing the lambda probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
4 Checking the fuel tank breather system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
4.1 Checking the fuel tank breather system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
4.2 Checking the solenoid valve 1 for the activated carbon canister . . . . . . . . . . . . . . . . . . . . . .71
5 Checking the throttle valve control unit - vehicles without CCS . . . . . . . . . . . . . . . . . . . . . .73
5.1 Checking the throttle valve control unit - vehicles without CCS . . . . . . . . . . . . . . . . . . . . . .73
5.2 Adaptation of the throttle valve control unit without CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . .73
5.3 Checking the idling switch without CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75
5.4 Checking the throttle valve potentiometer without CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
5.5 Checking the sensor for throttle valve positioner without CCS . . . . . . . . . . . . . . . . . . . . . .78
5.6 Checking throttle valve positioner without CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
6 Checking the throttle valve control unit - vehicles with CCS . . . . . . . . . . . . . . . . . . . . . . . .80
6.1 Checking the throttle valve control unit - vehicles with CCS . . . . . . . . . . . . . . . . . . . . . . . .80

Contents i
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

6.2 Adaptation of the throttle valve control unit with CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
6.3 Checking the idling switch with CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
6.4 Checking the throttle valve potentiometer with CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83
6.5 Checking the sensor for the throttle valve positioner with CCS . . . . . . . . . . . . . . . . . . . . . .85
6.6 Checking the throttle valve positioner with CCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
7 Cheocking auxiliary signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
7.1 Cheocking auxiliary signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
7.2 Checking air conditioner compressor shut-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
7.3 Checking the engine speed adaptation by switching on the air conditioner . . . . . . . . . . . . . .88
7.4 Checking selector lever position on automatic gearbox . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
7.5 Checking engine speed signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
7.6 Checking throttle valve positioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
7.7 Checking the speed signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
7.8 Checking the gearbox intervention signal when changing gear . . . . . . . . . . . . . . . . . . . . . .93
7.9 Checking clutch pedal switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94
7.10 Checking the power steering pressure switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95
7.11 Checking the Motronic system/ABS/gearbox data exchange (CAN bus) . . . . . . . . . . . . . . . .96

28 - Ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

1 Checking ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
1.1 Checking ignition system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
1.2 Safety precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
1.3 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
1.4 Checking ignition coils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98
1.5 Checking output stages for ignition coils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101
1.6 Checking the intake air temperature sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103
1.7 Checking the engine speed sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104
1.8 Checking the sensor for coolant temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105
1.9 Checking the power supply for the control unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
1.10 Checking the knock sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106
1.11 Checking the Hall sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

ii Contents
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

01 - Self-diagnosis

1 - Self-diagnosis for the Motronic system

1.1 - Self-diagnosis for the Motronic system

1.2 - Technical data for the self-diagnosis

Memory

The non-volatile memory in the engine control unit is independent of the power supply

Data output

Rapid data transfer

Address words
Address word 00 Automatic test routine Switch on ignition or leave engine idling
Address word 01 Engine electronics Switch on ignition or leave engine idling
Functions: permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

Function 01: Interrogating control unit version Switch on ignition or leave engine idling
with respect to the correctness of information in this document. Copyright by AUDI AG.

Function 02: Interrogating fault memory Switch on ignition or leave engine idling
Function 03: Final control diagnosis Switch on ignition.
Function 04: Basic setting Leave engine idling, or crank engine with starter for at least 5
seconds, without subsequently switching off the ignition

Functions:
Function 05: Erasing fault memory Switch on ignition or leave engine idling
Function 06: End of output Switch on ignition or leave engine idling
Function 07: Encoding control unit Switch on ignition.
Function 08: Reading measured value block Switch on ignition or leave engine idling or drive the car

1.1 - Self-diagnosis for the Motronic system 1

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

1.3 - Connecting the V.A.G 1551 fault reader and selecting the engine electronics control
unit

Note:

The V.A.G 1552 vehicle system tester may be used instead of the V.A.G 1551 fault reader, however a printout
is not possible.

Test conditions

• Battery voltage at least 11 V.

• Earth connections on engine and gearbox OK.
• Fuel pump relay OK.
• Fuses OK.

- -> Unclip the cover for the diagnostic connection.

- Connect the V.A.G 1551 fault reader or V.A.G 1552 vehicle system tester with cable V.A.G 1551/3.

-> Display readout:

V.A.G self-diagnosis HELP
1 - Rapid data transfer*
2 - Flash code output*

* displayed alternately

Note:

If the display remains blank:

=> Operating instructions for the fault reader

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Depending on the function required: with respect to the correctness of information in this document. Copyright by AUDI AG.

- Switch on the ignition.

or
start the engine => Page 1 , Table "Selectable functions".

- Switch on printer with the Print key

(the indicator lamp in the key lights up).

2 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Press key 1 for "Rapid data transfer".

-> Display readout:

Rapid data transfer HELP
Enter address word XX

-
Rapid data transfer Q
01 - Engine electronics

-> Press keys 0 and 1 for the address word "Engine electronics" and confirm entry by pressing the Q key.

-> If the display shows one of the messages reproduced here, perform the fault finding procedure according to
the fault finding program for diagnostic wiring.
Rapid data transfer HELP
Control unit does not answer

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
Rapid data transfer HELP
Communications fault

Rapid data transfer HELP

K wire not switching to earth

Rapid data transfer HELP

K wire not switching to positive

-> The control unit identification appears on the V.A.G 1551 fault reader, e.g.:
06A906018.. 1.8l R4/5VT MOTR HS
D..⇒
Encodierung 04000 WSC 06388

- 06A906018. Control unit number (see also spare

parts program)
- 1.8l Engine capacity
- R4/5VT In line engine, 4 cylinders, 5 valves,
turbo
- MOTR Motronic
- HS MG = Manual gearbox
AT AT = Automatic transmission
- D.. Status (software version) of control
unit
- Encoding 04000 Control unit encoding
- WSC 06388 Workshop Code from the V.A.G
1551 used to perform the last en‐
coding

- Press the ⇒key.

-> Display readout:

Rapid data transfer HELP
Select function XX

1.4 - Interrogating and erasing fault memory

- Connect the V.A.G 1551 fault reader (V.A.G 1552) and select the engine electronics control unit with the
"Address word" 01. The engine must be idling.
(Connecting the fault reader and selecting
AG does notthe engine electronics
any liability control unit => Page 2 ).
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI guarantee or accept
with respect to the correctness of information in this document. Copyright by AUDI AG.
-> Display readout:

1.3 - Connecting the V.A.G 1551 fault reader and selecting the engine electronics control

unit 3
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Rapid data transfer HELP

Select function XX

- Press keys 0 and 2 for the function "Interrogating fault memory" and confirm entry with the Q key.

-> The display will show either the number of faults stored or the message "No fault recognised!".
X faults recognised

If no fault is stored:
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- Press the ⇒ key. with respect to the correctness of information in this document. Copyright by AUDI AG.

If one or more faults are stored:

The stored faults are displayed in sequence and printed out.

-> Then the display will show:

Rapid data transfer HELP
Select function XX

- Localise and rectify the faults printed out in accordance with the error table => Page 4 .
- Press keys 0 and 5 for the function "Erasing fault memory" and confirm entry with the Q key.

-> Display readout:

Rapid data transfer
Fault memory erased!

Note:

If the ignition is switched off between the interrogation of the fault memory and the erasure of the fault memory,
the fault memory will not be erased.

- Press the ⇒key.

-> Display readout:

Rapid data transfer HELP
Select function XX

- Press keys 0 and 6 for the function "End of output" and confirm entry with the Q key.

1.5 - Fault table

Notes:

◆ The fault table is arranged according to the 5- digit fault code on the left.
◆ Sporadic faults are marked "SP" (sporadic fault) on the V.A.G 1551 display.
◆ If a stored fault does not appear within the next 40 engine starts, the fault code will be automatically erased.
◆ Before replacing components indicated as being faulty, check the wiring and connectors to these compo‐
nents and the earth connections against the current flow diagram.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00282
-V60 throttle valve positioner

4 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Implausible signal - Throttle valve sticking - Idling speed too high - Check the -V60 throttle
- Fault in the wiring for the - Idling speed control goes valve positioner without
throttle valve positioner into emergency operating CCS
mode => Page 86
- Cruise control system is Check the cruise control
switched off system
=> Electrical System; Re‐
pair Group 96

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00282
-V60 throttle valve position‐ Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
er permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Adaptation limit exceeded - -V60 throttle valve posi‐
with respect -toIdling speedof information
the correctness too highin this document.
- Check the -V60
Copyright by AUDIthrottle
AG.
tioner defective - Idling speed control goes valve positioner without
into emergency operating CCS
mode => Page 85
- Cruise control system is Check the cruise control
switched off system
=> Electrical System; Re‐
pair Group 96

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00515
-G40 Hall sensor
Open circuit/short to posi‐ - Open circuit or short to - No engine power at full - Check Hall sensor
tive positive throttle =>Page 108
- Sensor disc out of position - Emission values not OK
- -G40 defective - High fuel consumption
Short to earth - Short to earth
- -G40 defective
00528
F96 altitude sensor
Signal too high - Open circuit or short to - Possibly poor starting - Check altitude sensor
positive =>Page 63
- -F96 defective
Signal too low - Short to earth - Reduced boost pressure
- Fault in power supply to - (safety limitation for turbo‐
F96 charger speed)
- -F96 defective

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00532
Voltage supply
Signal too high - Excess voltage from assis‐ - Damage to the engine con‐ - Check battery voltage
ted start trol unit
- Alternator defective
Signal too low - Voltage supply less than 10 - Engine will not start - Check power supply to con‐
V for more than 1 second - Engine running problems, trol unit
- Poor wiring to engine con‐ engine may even stop =>Page 106
trol unit - Learning procedure for
throttle valve control unit not
possible

1.5 - Fault table 5

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Battery discharged - Check battery charge level

- Current drain with ignition
off

Notes on fault code 00532:

◆ If the fault is shown as a sporadic fault, ignore the fault message on the display. This fault is often stored
when the engine is left idling for a long period with a large number of electrical consumers switched on
causing the battery to become greatly discharged.
◆ The fault message "Signal too low" is stored if the supply voltage falls below 10.00 V for more than 1 second.
(The control unit will not function at less than 6.5 V.)

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00543
Maximum revs exceeded
- Engine over revving - Possible engine - Rectify mechanical
(e.g.
Protected by copyright. Copying for wrong
private gearpurposes,
or commercial engag‐in part
damage
or in whole, is not damage
ed)AG. AUDI AG does not guarantee or accept any liability
permitted unless authorised by AUDI
with respect to the correctness-ofEngine
informationspeed greater
in this document. Copyright by AUDI AG.
than 7100 rpm
00544
Maximum boost pressure exceeded
- Hoses interchanged, - Loss of power (over‐ - Check boost pressure
not connected, blocked run cut-off until boost control => Page 61
or leaking pressure falls to a non
- Solenoid valve for boost critical level)
pressure control defec‐
tive
- Pressure unit for turbo‐
charger defective
- Short to earth - Check solenoid valve
for boost pressure con‐
trol
=>Page 61
- Altitude sensor defec‐ - Reduced boost - Check altitude sensor
tive pressure =>Page 63

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00561
Mixture adaptation
Adaptation limit (add) ex‐ - Fuel system pressure - Vehicle bucking
- Fill up vehicle, check fuel
ceeded too low -system pressure => Page
50
Adaptation limit (mul) ex‐ - Incorrect signal from air - Increased fuel consump‐ - Check air mass meter =>
ceeded mass meter tion Page 59
- Leaks in exhaust system - Possibly rough idling - Rectify leaks
upstream of catalytic con‐ - Vehicle bucking
verter
- Unmetered air down‐
stream of air mass meter
- Coked injectors - Check injection quantity
=>Page 52

Notes:

◆ (add) = additive, i.e. fault only occurs during idling.

◆ (mul) = multiplicative, i.e. fault occurs throughout the entire engine speed range and load range.

6 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00561
Mixture adaptation
Adaptation limit (add) not - Fuel system pressure - Vehicle bucking - Fill up vehicle, check fuel
reached too low system pressure => Page
50
Adaptation limit (mul) not - Incorrect signal from air - Increased fuel consump‐ - Check air mass meter =>
reached mass meter tion Page 59
- Fuel in engine oil - Possibly rough idling - Drive vehicle on a motor‐
- Unmetered air down‐ - Vehicle bucking way for 15 minutes or
stream of air mass meter change oil
permitted unless authorised by AUDI AG. AUDI AG does Rectify leaks
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
not guarantee or accept any liability
- Injectors leaking with respect - Black smoke
to the correctness of information in this - Check injection
document. Copyright by AUDIquantity
AG.
=>Page 52

Notes:

◆ (add) = additive, i.e. fault only occurs during idling.

◆ (mul) = multiplicative, i.e. fault occurs throughout the entire engine speed range and load range.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00575
Intake manifold pressure
Control limit not reached - Signal from air mass meter - Increased power - Check air mass meter =>
too low Page 59
- Unmetered air between air - Check intake system
mass meter and turbocharger
- Turbocharger pressure unit - Poor performance - Check boost pressure control
sticking => Page 61
- Solenoid valve for boost pres‐
sure control defective
- Short circuit or open circuit
Control limit exceeded - Signal from air mass meter - Poor performance - Check air mass meter =>
too high Page 59
- Turbocharger pressure unit - Increased power - Check boost pressure control
sticking => Page 61
- Solenoid valve for boost pres‐
sure control defective

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00670
-G127 sensor for throttle valve po‐
sitioner
Signal too low - Short to earth - Idling speed too high - Check sensor for -
- Fault in power supply - No idling speed control G127 throttle valve po‐
to -G127 - Load change jolt on ac‐ sitioner without CCS =>
- -G127 defective celerator release Page 78
Signal too high - Open circuit or short to - AC compressor only - Check sensor for -
positive activated at high engine G127 throttle valve po‐
- Fault in earth supply to speeds sitioner with CCS =>
-G127 Page 85
- -G127 defective
Implausible signal - Throttle valve sticking
- Fault in wiring to -
G127

1.5 - Fault table 7

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Notes on fault code 00670:

◆ The sensor for the throttle valve positioner is located in the J338 throttle valve control unit.
◆ The sensor is a potentiometer, which reports the position of the throttle valve positioner to the control unit.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
00671
-E45 switch for CCS
Implausible signal - -E45 defective - Cruise control system is - Check the cruise control
- Open circuit or short circuit switched off system (CCS)
=> Electrical system; Repair
Group 01; Technical Bulletin
No. 2 Technical Bulletin No.
2

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
01119
Gear recognition
Protectedsignal
by copyright. Copying for private or commercial purposes, in part or in whole, is not
Open/shortpermitted
towithpositive - Open circuit or short to - Brief and slightly more pro‐
unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
respect to the correctness of information in this document. Copyright by AUDI AG.
- Check wiring to -F125 mul‐
positive nounced engine speed fluc‐ tifunction switch
- -F125 defective tuations when engaging or => Current Flow Diagrams,
disengaging a gear Electrical Fault Finding and
Fitting Locations binder
Short to earth - Short to earth - Interrogate the fault mem‐
- -F125 defective ory for gearbox
=> Automatic Gearbox 01M;
Repair Group 01; Self diag‐
nosis, Electrical check; Per‐
form self diagnosis Self di‐
agnosis, Electrical check;
Perform self diagnosis

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
01165
-J338 throttle valve control unit
Control limit not reached - Throttle valve sticking - Increased idling speed - Check throttle valve
- Actuator mechanics - Load change jolt on ac‐ control unit without CCS
sticking celerator release => Page 73
Control limit exceeded
Control difference - Open circuit to -V60 - Check throttle valve
throttle valve positioner control unit with CCS
=> Page 80

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
01182
Height adaptation
Signal outside tolerance - -G69 throttle valve potenti‐ - Starting problems - Check -G69 throttle valve
ometer defective - Poor throttle response potentiometer without CCS
=> Page 83
- Wrong throttle valve unit fit‐ - Starting problems - Check part number
ted
- Unmetered air - Rectify unmetered air
- Air cleaner blocked - Replace air cleaner

8 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

V.A.G 1551 printout Possible cause of Possible effects Fault remedy

fault
01247
-N80 solenoid valve 1 for activated car‐
bon canister
Short to earth - Short to earth - Possibility of buck‐ - Check solenoid valve 1
- -N80 defective ing in part load range for activated carbon
canister
=>Page 71
Short to positive - Short to positive - Car may smell of
- -N80 defective petrol
Output open - Open circuit
- -N80 defective

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
01249
Injector, cylinder 1 -N30
01250
Injector, cylinder 2 -N31
01251
Injector, cylinder 3 -N32
01252
Injector, cylinder 4 -N33
Short to earth - Short to earth - Irregular engine running - Check injectors
- Injector defective - Engine stops =>Page 53
Short to positive - Short to positive
- Injector defective
Output open - Open circuit
- Injector defective
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
01259
-J17 fuel pump relay
Open circuit/short circuit to - Open circuit - Engine will not start - Check fuel pump relay =>
earth - -J17 fuel pump relay - Engine stops Page 56
- -defective - Several faults may be re‐
corded
- Short to earth - Fuel pump runs continu‐
ously when ignition is on
Short to positive - Short to positive - Engine will not start
- Engine stops
- Several faults may be re‐
corded

Note:

If fault code "01259" has been stored, fault codes "01247 / 01249 / 01250 / 01251 / 01252 / 1262 / 16486" may
also be stored, as these components are supplied with power from the fuel pump relay.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
01262
-N75 solenoid valve for boost pres‐
sure control

1.5 - Fault table 9

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Short to earth - Short to earth - Loss of power (over‐ - Check solenoid valve
- -N75 defective run cut-off until boost for boost pressure con‐
pressure falls to a non trol
critical level) =>Page 61
- Boost pressure too
high
- Fault 0544 maximum
boost pressure excee‐
ded/ stored
Short to positive - Short to positive - Poor performance
- -N75 defective - Boost pressure too
low
Output open - Open circuit
- -N75 defective

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
01314
Engine control unit
Defective - CCS not working - Replace engine control unit => Page 48

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16486
-G70 air mass meter
Signal too low - Open circuit or short to earth - Scarcely perceptible - Check air mass meter =>
- -G70 defective change in performance Page 59
- Unmetered air - Check intake system
- Air cleaner blocked
16487
-G70 air mass meter
Signal too high - Open circuit or short to pos‐ - Scarcely perceptible - Check air mass meter =>
permitted unless authoriseditive change
accept anyin performance Page 59
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
by AUDI AG. AUDI AG does not guarantee or liability
- -G70
with respect to the correctness defective
of information in this document. Copyright by AUDI AG.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16496
-G42 sensor for intake air temper‐
ature.
Signal too low - Short to earth - Emergency operation - Check sensor for intake
- -G42 defective (substitute value con‐ air temperature
stant +19.5 °C) =>Page 103
16497
-G42 sensor for intake air temper‐
ature
Signal too high - Open circuit or short - Emergency operation - Check sensor for intake
to positive (substitute value con‐ air temperature
- -G42 defective stant +19.5 °C) =>Page 103

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16500
-G62 sensor for coolant temper‐
ature

10 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Implausible signal - Moisture or corrosion - Cold start problems at - Check sensor for intake
on connector very low temperatures air temperature
- Loose contact - Engine running prob‐ =>Page 105
- -G62 defective lems when warm
16501 - Increased fuel con‐
-G62 sensor for intake air tem‐ sumption
perature - Emission values not OK
Signal too low - Short to earth
- -G62 defective
16502
-G62 sensor for coolant temper‐
ature
Signal too high - Open circuit or short
to positive
- -G62 defective

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16505
-G69 throttle valve potentiome‐
ter
Implausible signal - Moisture or corrosion in - Acceleration bucking - Check -G69 throttle
the connector - Rough idling valve potentiometer
- -G69 defective without CCS => Page
76
16506
-G69 throttle valve potentiome‐
ter
Signal too low - Open circuit or short to - Acceleration bucking - Check -G69 throttle
earth - Load change jolt on ac‐ valve potentiometer with
- -G69 defective celerator release CCS => Page 83
16507
-G69 throttle valve potentiome‐
ter
Signal too high - Open circuit or short to - Acceleration bucking
positive - Load change jolt on ac‐
- -G69 defective celerator release

Note on fault code 16505:

The air throughput (air mass) at the relevant speed is checked with the throttle angle.

NotesProtected
on fault codes 16505, 16506 and 16507:
by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
◆ As soon as the
with respect error
to the is identified,
correctness of informationthe control
in this unit
document. usesbyaAUDI
Copyright substitute
AG. value formed from the speed.
◆ If an error occurs simultaneously on the G69 throttle valve potentiometer and the air mass meter, no emer‐
gency operation function is possible. Consequence: The engine stalls.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16514
Bank 1 - Probe 1
Electrical fault in circuit - Corrosion due to mois‐ - Lambda control not work‐ - Check lambda control
ture on connector ing (mixture formation is =>Page 67
- Short circuit between sig‐ controlled)
nal line for lambda probe
and reference earth wire
for lambda probe

1.5 - Fault table 11

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Amplitude in signal line - Rough idling - Check lambda probe sig‐

too low (lambda probe - Emission values not OK nal line and actuation =>
contaminated or probe - Increased fuel consump‐ Page 69
slots clogged or dirty) tion

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16515
Bank 1 - Probe 1
Voltage too low - Short to earth or short to - Lambda control not working - Check lambda control
screening in lambda probe sig‐ (mixture formation is controlled) =>Page 69
nal line - Rough idling
- Short to earth or short to - Emission values not OK
screening in lambda probe ref‐ - Increased fuel consumption
erence earth line
- Lambda probe defective
16516
Bank 1 - Probe 1
Voltage too high - Short to positive in signal line

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16518
Bank 1 - Probe 1
No activity - Short to earth in refer‐ - Rough idling - Check lambda control
ence earth line - Emission values not OK =>Page 67
- Lambda probe defective
(dirty)
- Lambda probe heating - Increased fuel consump‐ - Check fuel pump relay =>
not functioning tion Page 68
- Soot deposits on spark
plugs
16519
Bank 1 - Probe 1
Electrical fault in heating - Open circuit or short cir‐ - Lambda probe heating not - Check lambda probe
circuit cuit functioning heating => Page 68

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16705
-G28 engine speed sensor
Implausible signal - Sensor disc loose or bent - Poor starting - Remove oil sump and check
- Engine misfiring sensor disc
- -G28 engine speed sensor - Check engine speed sensor
defective =>Page 104
- Loose contact
- Open circuit in screening
16706
-G28 engine speed sensor
No signal - Open circuit or short circuit - Engine will not start - Check engine speed sensor
- -G28 engine speed sensor - Engine cuts out =>Page 104
loose or defective

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16711
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
-G61 knock sensor 1 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Signal too low with respect to the correctness of information in this document. Copyright by AUDI AG.

12 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

16716
-G66 knock sensor 2
Signal too low - Knock sensor loose or cor‐ - High fuel consumption - Tightening torque for knock
rosion on connector - Poor performance sensor: 20 Nm
- Open circuit or short to earth - Check knock sensor
- Knock sensor defective =>Page 106

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
16885
Vehicle speed signal
Implausible signal - Open circuit between -G22 - Engine control unit does not - Check speed signal =>
speedometer sensor and deactivate air conditioner Page 92
dash panel insert compressor
- Open circuit between dash - Poor load change perform‐
panel insert and engine con‐ ance
trol unit
- -G22 defective
- Dash panel insert defective
16989
Control unit defective
- Engine control unit defec‐ - Engine will not start - Replace engine control
tive unit => Page 48

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
17733
Knock control cyl. 1
17734
Knock control cyl. 2
17735
Knock control cyl. 3
17736
Knock control cyl. 4
Control limit reached - Poor quality fuel (less than - High fuel consumption - Fill up with petrol of at least
RON 91) - Poor performance RON 91
- Irregular engine running
- Knock sensor tightened with - Tighten knock sensor (20
incorrect torque Nm)
- Abnormal engine noise (an‐ - Check knock control
cillaries loose) => Page 106

V.A.G 1551 printoutProtected byPossible cause

copyright. Copying for of fault
private Possible
or commercial effects
purposes, in part or in whole, is not Fault remedy
17913 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
-F60 idling switch
Does not close / open cir‐ - Throttle cable setting - Idling speed too high - Adjust throttle cable
cuit - Floor mat pressing down => 4-cylinder engine, me‐
on accelerator chanical components; Re‐
pair Group 20; fuel supply;
repair throttle mechanism
fuel supply; repair throttle
mechanism

1.5 - Fault table 13

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Throttle valve sticking - Idling speed control not - Check idling switch
- Open circuit or short to functioning =>Page 75
positive - Load change jolt on ac‐
- -F60 idling switch defec‐ celerator release
tive - AC compressor only acti‐
vated at high engine
speeds
17914
-F60 idling switch
Does not open / short to - Moisture in throttle valve
earth connector
- Short to earth
- -F60 idling switch defec‐
tive

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
17953
Throttle valve control
Faulty - Open circuit - Idling speed too high - Check -J338 throttle valve
- Throttle valve stiff or dirty - Load change jolt on accel‐ control unit - without CCS
- -G69 and -G127 defective erator release => Page 80
17966
Throttle valve drive
Electrical fault in circuit - Short to earth - Idling speed too high - Check throttle valve posi‐
- short to positive tioner without CCS =>
- -V60 throttle valve posi‐ Page 86
tioner defective

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
17967
-J338 throttle valve control
unit Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Fault in basic setting - Idling switch open or permitted
- Adaptation of throttle - Adapt the throttle valve
unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
open circuit valve control unit not per‐ control unit
- Throttle valve sticks and formed => Page 80
will not close
- Pulse detected by engine
speed sensor
17972
-J338 throttle valve control
unit
Undervoltage in basic - Voltage less than 10 V - Check voltage, read
setting during basic setting measured value blockDis‐
play Group 03, display
zone 2=> Page 30

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
17978
Engine control unit
blocked
- Attempted tampering - Engine starts but cuts out - Adapt engine electronics
again immediately control unit to electronic im‐
mobilizer
=> Electrical System; Repair
Group 01; immobilizer self-di‐
agnosis

14 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Short circuit in the commu‐ - Check the electronic immo‐

nication line bilizer
=> Electrical System; Repair
Group 01; immobilizer self-di‐
agnosis
- Immobilizer control unit de‐
fective/missing

Note on fault code 17978:

If an attempt is made to start the car with a key which has not been adapted, a static fault will be recorded. If
the car is then started with a correctly adapted key, the fault will be re-classified as a sporadic fault.

V.A.G 1551 printout Possible cause of fault Possible effects Fault remedy
18010
Power supply term. 30
Voltage too low - Battery was discon‐ - All learned values - Erase fault memory
nected erased and continue to observe
vehicle
- Open circuit - Check power supply for
control unit
=>Page 106
18020
Engine control unit incorrectly en‐
coded
- Engine control unit in‐ - Loss of performance - Encode control unit
correctly encoded - Increased emission val‐ =>Page 19
ues
- Various faults in fault
memory

V.A.G 1551 printout Possible cause of Possible effects Fault remedy

fault
18034
CAN bus fault. Message from AGgearbox
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI does not guarantee or accept any liability
withcontrol
respect to unit
the correctness of information in this document. Copyright by AUDI AG.
- Fault in the data - Automatic gearbox - Checking the Motron‐
lines to the gearbox goes into emergency ic system/ABS/gear‐
control unit operation box data exchange
- Engine running prob‐ (CAN bus) => Page
lems (gearshift jolt, 96
load change jolt)
18259
CAN bus fault. Message from ABS
control unit
- Fault in the data line - No driving dynamics - Checking the Motron‐
to the ABS control unit control ic system/ABS/gear‐
(antilock system) box data exchange
(CAN bus) => Page
96

1.6 - Final control diagnosis

Notes:
◆ The final control diagnosis can only be performed with the engine stopped and the ignition switched on.
◆ The final control diagnosis will be terminated if the engine is started or if an engine speed pulse is detected.

1.5 - Fault table 15

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

◆ During the final control diagnosis, individual control elements continue to be actuated until the test pro‐
gramme is advanced to the next control element by pressing the ⇒ key.
◆ The control elements can be checked either by listening or by touching.
◆ Before repeating the final control diagnosis, without starting the engine briefly, switch off the ignition for
approx. 20 seconds.
◆ The electric fuel pump runs continuously throughout the final control diagnosis.
◆ The final control diagnosis is terminated after 10 minutes.

The final control diagnosis activates the following components in the stated sequence:

1. Injector, cylinder 1 -N30

2. Injector, cylinder 2 -N31

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
3. Injector, cylinder 3 -N32
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

4. Injector, cylinder 4 -N33

5. -N80 solenoid valve 1 for activated carbon canister

6. -N75 solenoid valve for boost pressure control

- Connect the V.A.G 1551 fault reader (V.A.G 1552) and select the engine electronics control unit with the
"Address word" 01. During this, the ignition must be switched on.
(Connecting the fault reader and selecting the control unit for the engine electronics => Page 2 .)

-> Display readout:

Rapid data transfer HELP
Select function XX

- Press keys 0 and 3 for the function "Final control diagnosis".

-> Display readout:

Rapid data transfer Q
03 - Final control diagnosis

- Confirm input with the Q key.

-> Display readout:

Final control diagnosis
Injector, cylinder 1 -N30

- Turn the throttle mechanism on the throttle valve control unit to open the idling switch.

The injector should click five times.

- To switch to the next injector, press the⇒ key. (It is also possible to advance the programme without checking
the injector in question.)
- Use this procedure to check all the injectors in sequence.

If one of the injectors is not actuated (does not click):

- Check the injectors => Page 53

- Press the ⇒key.

-> Display readout:

Final control diagnosis
-N80 solenoid valve 1 for activ. carb.
canistor

This solenoid valve will continue to be actuated (clicks) until the ⇒ key is pressed to switch to the next control
element.

16 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the valve is not actuated (does not click):

- Check the -N80 solenoid valve for the activated carbon canister =>Page 71 .
- Press the ⇒key.

-> Display readout:

Final control diagnosis
-N75 solenoid valve for boost pressure
control

This solenoid valve will continue to be actuated (clicks) until the ⇒ key is pressed to switch to the next control
element.

Note:

The clicking of the valve is difficult to hear and it is therefore best checked by touch.

If the valve is not actuated (does not click):

- Check the solenoid valve for boost pressure control

=>Page 61
- Press the ⇒key.

Note:

The final control diagnosis cannot be re-started until the ignition has been switched off briefly.

1.7 - Basic setting

With the engine stopped, the following operation can be performed with the basic setting:

◆ Adaptationpermitted
of the unless
throttle valveby control unitAG
to does
thenot
engine control
or acceptunit => Display Group 98
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
authorised AUDI AG. AUDI guarantee any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
With the engine running, the following operations can be performed with the basic setting:

◆ Learning process for lambda control

=> all display groups
◆ Fault finding by selective actuation and deactuation of the lambda control => Display Group 99
◆ Check the ignition timing
=> Display Group 95

Test conditions for operations with engine running

• Coolant temperature at least 80 °C

• Electrical consumers switched off (radiator fan must not run during the test)

• Air conditioner switched off

• Gear selector lever in P or N position
• No fault stored in fault memory

- Connect the V.A.G. 1551 fault reader and select the engine electronics control unit.
=> Page 2 .
- Interrogating and erasing fault memory.
=> Page 3 No faults must be stored (if necessary, rectify fault, erase fault memory, switch off and re-start
engine, perform test drive and interrogate the fault memory again as a check.
- Leave engine idling.

-> Display readout:

Rapid data transfer HELP
Select function XX

1.6 - Final control diagnosis 17

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Press keys 0 and 4.

(04 is used to select the function "Basic Setting")

-> Display readout:

Rapid data transfer Q
04-Basic setting

- Confirm entry by pressing the Q key.

-> Display readout:

Basic setting Q
Enter display group number XXX

- Enter the required display group number according to the list of display groups in "Reading measured value
block" => Page 21 .

Note:

Display Group number 00 is used here as an example to demonstrate the procedure.

- Press key 0 three times.

(000 is used to select the function "Display Group 00").

-> Display readout:

Basic setting Q
Enter display group number 00

- Confirm entry by pressing the Q key.

-> Display readout:

Basic setting 0 Q
1 2 3 4 5 6 7
8 9 10

Display group 00 (decimal value)

▪ Engine running at idling speed
Display zones Specified value Corresponds to
1 2 3 4 5 6 7 8 9 10 Learned value for mixture formation 118...138 -8...+8 %
(if outside tolerance, perform test drive)
Learned value for mixture formation 115...141 -0.64...+0.64 ms
(if outside tolerance, perform test drive)
Control value for mixture formation 78...178 -10...+10 %
(if outside tolerance, perform test drive)
Learned value for idle stabilisation 120...136 -4.0...+4.0 kg/h
Control value for idle stabilisation 122...134 -3.0...+3.0 kg/h
Throttle angle 0...12 0...5 °
Battery voltage 142...206 10...14.5 V
Engine speed (idling speed) 80...92 800...920 rpm1)
Engine load (no consumers) 10...30 0.5...1.5 ms
Coolant temperature (pre-condition for basic setting) 170...204 80...105 °C

1) Current values:

=> Exhaust Emissions Check permitted

binder unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

with respect to the correctness of information in this document. Copyright by AUDI AG.

18 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Run engine at idling speed for a few minutes, coolant temperature at least 80 °C.

Display zone 1: specified value at least 170)

Notes:

◆ Each time the PRINT key is pressed, the current display is printed out.
◆ Press the C key before selecting further display groups.

- If the specified values are achieved in all display zones, press the ⇒ key.

-> Display readout:

Rapid data transfer HELP
Select function XX Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
- Press keys 0 and 6.

(06 is used to select the function "End of output".)

-> Display readout:

Rapid data transfer Q
06 - End of output

- Confirm entry by pressing the Q key.

-> Display readout:

Rapid data transfer HELP
Select function XX

1.8 - Encoding the control unit

If the appropriate code for the vehicle is not displayed or if the control unit has been replaced, the control unit
must be encoded as follows.

- Connect the V.A.G 1551 fault reader (V.A.G 1552) and select the engine electronics control unit with the
"Address word" 01. During this, the ignition must be switched on.
(Connecting the fault reader and selecting the control unit for the engine electronics => Page 2 ).

-> Display readout:

Rapid data transfer HELP
Select function XX

- Press keys 0 and 7 for the function "Encoding control unit" and confirm entry with the Q key.

-> Display readout:

Encode control unit Q
Input code number xxxxx (0- 32000)

- Enter the appropriate code number for this vehicle and confirm with the Q key.

Encoding variants =>Page 20

Compose the code number as follows (example):

Member State of the European Union 04

Front wheel drive without traction slip control 0
5-speed manual gearbox 0
Audi A3 0

1.7 - Basic setting 19

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Code number 04 0 0 0

-> The control unit identification appears on the V.A.G 1551 fault reader, e.g.:
8D0907557.. 1.8l R4/5VT MOTR HS
D.. ⇒
Code 04000 WSC 12345

- Switch the ignition off and then on again.

Note:

The next time the ignition is switched on, the code entered will be activated.

- Press the ⇒key.

-> Display readout:

Rapid data transfer HELP
Select function XX

- Press keys 0 and 6 for the function "End of output" and confirm entry with the Q key.

Encoding variants for the engine control unit

Country/emissions Drive / auxiliary functions Gearbox Vehicle type

00 = --- 0 = Front wheel drive without 0 = 5-speed manual gearbox 0 = Audi A3
traction slip control
01 = --- 1= --- 1= --- 1= ---
02 = Non Member State of the Eu‐ 2 = Four wheel drive without 2= --- 2= ---
ropean Union (MVEG I) traction slip control
03 = --- 3= --- 3 = Automatic gearbox 01V 3= ---
04 = Member State of the Euro‐ 4 = --- 4= --- 4= ---
pean Union (MVEG II)
05 = --- 5= --- 5= --- 5= ---
06 = --- 6= --- 6= --- 6= ---
07 = --- 7= --- 7= --- 7= ---
08 = China and Commonwealth 8 = --- 8= --- 8= ---
of Independent States (CIS)
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
1.9 - Reading measured value block

Test conditions

• Coolant temperature at least 80 °C

• Electrical consumers switched off (radiator fan must not run during the check)
• Air conditioner switched off
• Gear selector lever in P or N position

- Connect the V.A.G 1551 fault reader (V.A.G 1552) and select the engine electronics control unit with the
"Address word" 01. During this, the engine must be running at idling speed.
(Connecting the fault reader and selecting the control unit for the engine electronics => Page 2 ).

-> Display readout:

Rapid data transfer HELP
Select function XX

20 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Press keys 0 and 8 for the function "Reading measured value block" and confirm entry with the Q key.

- Enter the desired display group number and confirm entry with the Q key.

-> Display readout (for example):

Read measured value block 0
1 2 3 4 5 6 7
8 9 10

Note:

To change to another display group, proceed as follows:

Display group V.A.G 1551 V.A.G 1552

Up Press key 3 Press ↑ key
Down Press key 1 Press the ↓ key
Skip Press the C key Press the C key
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
List of display groups permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Display Group no. Display Readout Meaning

00 Read measured value 1 = Coolant temperature
block 00
Basic function 1 2 3 4 5 6 7 8 9 10 2 = Engine load
3 = Engine speed
4 = Battery voltage
5 = Throttle angle
6 = Control value for idling air mass
7 = Learned value for idling air mass
8 = Control value for mixture formation (lambda control value)
9 = Learned value for mixture formation (lambda learned value)
10 = Learned value for mixture formation (lambda learned value)

Display Group no. Display Readout Meaning

01 Read measured value block 1 = Engine speed
1
Basic function 1 2 3 4 2 = Engine load (injection period per crankshaft revolution)
3 = Throttle angle
4 = Ignition timing
02 Read measured value block 1 = Engine speed
2
Basic function 1 2 3 4 2 = Engine load (injection period per crankshaft revolution)
3 = Injection period (per engine cycle)
4 = Intake air mass
03 Read measured value block 1 = Engine speed
3
Basic function 1 2 3 4 2 = Battery voltage
3 = Coolant temperature
4 = Intake air temperature

1.9 - Reading measured value block 21

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Display Group Display Read‐ Meaning

no. out
04 Read meas‐ 1 = Throttle angle
ured value
block 4
Idle 1234 2 = Learned value for idle stabilisation for manual gearbox and automatic
stabilisation gearbox with no gear engaged
3 = Learned value for idle stabilisation for automatic gearbox with gear en‐
gaged
4 = Operating status
Idling speed
Part load
Overrun
Enrichment
05 Read meas‐ 1 = Engine speed (actual)
ured value
block 5
Idling- 1234 2 = Engine speed (specified)
stabilisation 3 = Control value for idle stabilisation (idling speed control)
4 = Intake air mass

Display Group no. Display Readout Meaning

06 Read measured value block 6 1 = Engine speed
Idling- 1234 2 = Control value for idle stabilisation (idling speed control)
stabilisation 3 = Control value for mixture formation (lambda control val‐
ue)
4 = Ignition timing
07 Read measured value block 7 1 = Control value for mixture formation (lambda control val‐
ue)
Lambda control 1 2 3 4 2 = Lambda probe voltage
. 3 = Signal ratio for -N80 solenoid valve 1 for activated car‐
bon canister
4 = Correction factor for mixture formation with active fuel
tank breather system
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
08 Read permitted
measured unless value block
authorised 8 AG.
by AUDI 1 =AUDI
Injection
AG does notperiod (per
guarantee engine
or accept cycle)
any liability

Lambda control 1 2 3 4 2 = Control value for mixture formation at idling speed (ad‐
with respect to the correctness of information in this document. Copyright by AUDI AG.

ditive)
learned values 3 = Learned value for mixture formation at part load (multi‐
plicative)
4 = Fuel tank breather system:
TB active Fuel tank breather system active
TB not active Fuel tank breather system not active
λ-Adaptation Fuel tank breather system not active,
learning process for mixture formation in
progress

Display Group Display Read‐ Meaning

no. out
09 Read meas‐ 1 = Engine speed
ured value
block 9
Lambda 1234 2 = Control value for mixture formation (lambda control)
learned values 3 = Lambda probe voltage
4 = Control value for mixture formation at idling speed (additive)

22 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Display Group Display Read‐ Meaning

no. out
10 Read meas‐ 1 = Signal ratio for -N80 solenoid valve 1 for activated carbon canister
ured value
block 10
Tank 1234 2 = Correction factor for mixture formation with active fuel tank breather sys‐
tem
breather 3 = Fill level of -N80 activated carbon canister
4 = Air from fuel tank breather system as a proportion of total air mass
11 Read meas‐ 1 = Engine speed
ured value
block 11
Fuel 1234 2 = Engine load (injection period per crankshaft revolution)
consumption 3 = Speed
4 = Fuel consumption

Display Group no. Display Readout Meaning

12 Read measured value block 1 = Engine speed
12
Fuel 1234 2 = Battery voltage
consumption 3 = Fuel consumption
4 = Ignition timing
13 Read measured value block 1 = Cylinder 1 ignition timing retardation by knock control
13
Knock 1234 2 = Cylinder 2 ignition timing retardation by knock control
control 3 = Cylinder 3 ignition timing retardation by knock control
4 = Cylinder 4 ignition timing retardation by knock control
14 Read measured value block 1 = Engine speed
14
Knock 1234 2 = Engine load (injection period per crankshaft revolution)
control Protected by copyright. Copying for private or 3 = Cylinder
commercial 1inignition
purposes, timing
part or in whole, retardation 1 by knock control
is not
4 = Cylinder 2 Ignition timing
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
retardation by knock control

Display Group no. Display Readout Meaning

15 Read measured value block 1 = Engine speed
15
Knock 1234 2 = Engine load (injection period per crankshaft revolution)
control 3 = Cylinder 3 ignition timing retardation by knock control
4 = Cylinder 4 ignition timing retardation by knock control
16 Read measured value block 1 = Knock sensor signal, cylinder 1
16
Knock 1234 2 = Knock sensor signal, cylinder 2
control 3 = Knock sensor signal, cylinder 3
4 = Knock sensor signal, cylinder 4
17 Read measured value block 1 = Engine speed
17
Catalyst 1234 2 = Engine load
heating 3 = Energy balance for catalyst heating
4 = Ignition timing

1.9 - Reading measured value block 23

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Display Group Display Readout Meaning

no.
18 Read measured 1 = Engine speed
value block 18
Altitude 1234 2 = Engine load without altitude correction
correction 3 = Engine load with altitude correction
4 = Correction factor for mixture formation based on air density (altitude)
19 Read measured 1 = Engine speed
value block 19
Torque 1234 2 = Engine load (injection period per crankshaft revolution)
reduction 3 = Gearbox intervention
up to model year 4 = Ignition timing
1998
19 Read measured 1 = Engine speed
value block 19
Torque 1234 2 = Engine load (injection period per crankshaft revolution)
reduction 3 = Signals
from model year Pressure switch for power steering
1998 Gearbox intervention
Clutch pedal switch
4 = Ignition timing

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Display Group no. Display Readout Meaning
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
20 Read measured value block 20 1 = Engine speed
Operating 1234 2 = Selector lever position
conditions Neutral Selector lever in position P or N
Gear engaged Selector lever at 1, 2, 3 , D, or manual
gearbox
3 = Air conditioner
High High heating or cooling power
Low low heating or cooling power
4 = Air conditioner compressor
Compr.OFF Air conditioner compressor off
Compr.ON Air conditioner compressor on
21 Read measured value block 21 1 = Engine speed
Operating 1234 2 = Engine load (injection period per crankshaft revolu‐
tion)
conditions 3 = Coolant temperature
Lambda 4 = Lambda control
control λ-control OFF Lambda control off
λ-controlON Lambda control on

Display Group no. Display Readout Meaning

22 Read measured value block 22 (Ignore)
1234
23 Read measured value block 23 1 = Learning demand display
Throttle 1234 1 X X X X X Potentiometer characteristics learned
valve X 0 X X X X Adaptation to engine control unit com‐
pleted
control unit X X 0 X X X Upper stop position learned by -G69
throttle valve potentiometer

24 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

X X X 0 X X Lower stop position learned by -G69

throttle valve potentiometer
X X X X 0 X Upper stop position learned by -G127
throttle valve positioner
X X X X X 0 Upper stop position learned by -G127
throttle valve positioner
2 = Lower stop of throttle valve positioner
3 = Emergency running stop for throttle valve positioner
4 = Upper stop of throttle valve positioner

Display Group Display Read‐ Meaning

no. out
24 Read meas‐ 1 = Engine speed
ured value
block 24
Knock 1234 2 = Engine load (injection period per crankshaft revolution)
control 3 = Ignition timing
4 = Total ignition timing retardation for cylinders 1 to 4
25 Read meas‐ 1 = Specified engine load (driver's requirement via accelerator pedal)
ured value
block 25
boost pres‐ 1 2 3 4 2 = Specified engine load after correction based on knock control, altitude and
sure coolant temperature
control 3 = Actual engine load
4 = Signal ratio for -N75 boost pressure control solenoid valve

Display Group Display Read‐ Meaning

no. out
26
Protected Read meas‐
by copyright. 1 =orControl
Copying for private commercialvalue for
purposes, idleor stabilisation
in part in whole, is not (idling speed control)
ured
permitted unless valueby AUDI AG. AUDI AG does not guarantee or accept any liability
authorised
block 26
with respect to the correctness of information in this document. Copyright by AUDI AG.

1234 2 = Learned value for idle stabilisation with manual gearbox and with auto‐
matic gearbox with no gear engaged
3 = Coolant temperature
4 = Engine speed
27 Read meas‐ 1 = Engine load reduction by knock control
ured value
block 27
1234 2 = Engine load (actual) after reduction
3 = Engine speed
4 = Signal ratio for solenoid valve for boost pressure control -N75
66 Read meas‐ 1 = Switch settings for operating switch (CCS)
ured value
block 66
Cruise control 1 2 3 4 2 = Driving speed (actual)
system
(CCS) 3 = Switch settings Brake, clutch, CCS released
4 = Driving speed (specified)

Display Group no. Display Readout Meaning

98 Read measured value block 98 1 = Voltage from throttle valve potentiometer -G69
Throttle 1234 2 = Voltage from throttle valve positioner -G127
valve 3 = Operating status
control unit Idling speed

1.9 - Reading measured value block 25

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Part load
Overrun
Enrichment
4 = Adaptation status (ADP = adaptation)
ADP. running Adaptation in progress
ADP. OK Adaptation successfully completed
ADP. ERROR An error has occurred in the adapta‐
tion process

Display Group no. Display Readout Meaning

99 Read measured value block 99 1 = Engine speed
Lambda 1234 2 = Coolant temperature
control 3 = Control value for mixture formation (lambda control)
4 = Lambda control
λ-control OFF Lambda control off
λ-controlON Lambda control on

1.10 - Reading measured value block: Display Groups 00 to 10

Display group 00 (decimal values)

▪ Engine running at idling speed
Display zones Specified value Corresponds to
1 2 3 4 5 6 7 8 9 10 Learned value for mixture formation 118...138 -8...+8 %
(if outside tolerance, perform test drive)
Learned value for mixture formation 115...141 -0.64...+0.64 %
(if outside tolerance, perform test drive)
Control value for mixture formation 78...178 -10...+10 %
(if outside tolerance, perform test drive)
Learned value for idle stabilisation 120...136 -4.0...+4.0 kg/h
Control value for idle stabilisation 122...134 -3.0...+3.0 kg/h
Throttle angle 0...12 0...5 °
Battery voltage 142...206 10...14.5 V
Engine speed (idling speed) 80...92 800...920 rpm1)
Engine load (no consumers) 10...30 0.5...1.5 ms
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Coolant temperature (pre-condition for basic setting)
with respect to the correctness of information in this 170...204
document. Copyright by AUDI80...105
AG. °C

1) Current values:

=> Exhaust Emissions Check binder

Test table, Display Group 00

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

1 greater than 204 - -G62 sensor for coolant temperature - Check -G62 => Page 105
- Wiring to engine control unit
less than 170 - -G62 sensor for coolant temperature - Check -G62 => Page 105
- Wiring to engine control unit

26 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

- Coolant thermostat constantly open - Check coolant thermostat

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

2 greater than 30 - Air conditioning system switched - Switch off the air conditioner
on
- Electrical consumers on - Switch off the consumers
- Lambda control at rich or lean - Check the lambda control
stop => Page 67
- Air conditioner compressor run‐ - Check air conditioner compres‐
ning although air conditioner is off sor control => Page 87
less than 10 - Unmetered air downstream of air - Rectify fault
mass meter
- Unmetered air downstream of
throttle valve
- Vacuum hose disconnected
- Fuel pressure regulator

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

3 less than 80 - Drive position engaged (auto‐ - Put selector lever in P or N position
matic gearbox)
- Engine loaded by ancillaries - Remove load (e.g. air conditioner,
power steering)
- -J338 throttle valve control unit - Check J338 throttle valve control
sticking or defective unit =>Page 79
greater than 92 - -F60 idling switch open or defec‐ - Interrogate the fault memory and
tive check/adjust idling switch
- Large quantity of unmetered air - Rectify unmetered air
(cannot be compensated by idling
speed stabiliser )
- -J338 throttle valve control unit - Check -J338 throttle valve control
sticking or defective unit =>Page 79

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

4 less than 142 - Alternator defective, battery - Test voltage, charge battery
heavily discharged
- Heavy high load on electrical - Slightly increase engine speed for
system shortly after starting en‐ several minutes and switch off an‐
gine due to high charging current cillaries
and load from ancillaries
- Contact resistance in positive - Check power supply to engine
supply or earth connection for en‐ control unit
gine control unit =>Page 106
- Current drain with ignition off - Rectify current drain
greater than 206 - Voltage regulator on alternator - Test voltage; if necessary replace
defective regulator
Protected by copyright. Copying for private or commercial purposes,-inExcess voltage
part or in whole, is not from assisted - Interrogate the fault memory
permitted unless authorised by AUDI AG. AUDI AG does not guarantee start or high
or accept speed
any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
charging =>Page 3

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

5 less than 0 - Not possible

1.10 - Reading measured value block: Display Groups 00 to 10 27

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

greater than 12 - Basic setting of throttle valve con‐ - Perform basic setting of throttle
trol unit not performed valve control unit
=> Page 3
- Throttle control cable not OK - Adjust throttle cable
- Throttle valve potentiometer in => 4-cylinder engine, mechanical
throttle valve control unit defective components; Repair Group 20; re‐
move and install parts of the fuel
supply; repair throttle mechanism
remove and install parts of the fuel
supply; repair throttle mechanism
- Throttle valve mechanism sticking - Rectify fault, replace if necessary
6 less than 122 - Unmetered air downstream of - Eliminate unmetered air
throttle valve
greater than 134 - Increased engine load from ancil‐ - Remove load by switching off an‐
laries cillaries

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

7 less than 120 - Unmetered air downstream of - Eliminate unmetered air
throttle valve
greater than 136 - Increased engine load from ancil‐ - Reduce load by switching off an‐
laries cillaries
8 less than 78 - Mixture too rich; lambda control - Press down on accelerator pedal
makes it leaner at 20 second intervals until the
learning process has been per‐
formed
- Large quantity of fuel from ACF
system (not with basic setting)
- Leak in vacuum hose for fuel - Replace vacuum hose
pressure regulator
- Lambda learned values at stop - Check lambda-learned values,
Display Group 08 =>Page 32

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

8 greater than 178 - Mixture too lean; lambda control - Check injection quantity
makes it by
Protected richer => Page
copyright. Copying for private or commercial 52 in part or in whole, is not
purposes,
- Unmetered
permitted unlessair
authorised by AUDI AG. AUDI AG - Eliminate unmetered
does not guarantee airliability
or accept any
with respect to the correctness of information in this document. Copyright by AUDI AG.
- Injectors defective
- Lambda learned values at stop - Check lambda-learned values,
Display Group 08 =>Page 32
Readout fluctuates - Fuel reserve too low - At least 10 l of fuel in the tank
or remains - Lambda mixture control is on
constant at 128 open loop control
9 less than 115 - Display Group 08, display panels
or 2 and 3 =>Page 32
greater than 141
10 less than 118 - Display Group 08, display panels
or 2 and 3 =>Page 32
greater than 138

Display Group 01 - Basic function at idling speed (engine warm, coolant temperature not below +85 °C):

Read measured value block 1 ⇒ ◂ Display readout

800...920 rpm 0.5...1.5 ms 0...5 <° 3...12 °
BTDC

28 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Ignition timing
▪ 3...12.0°BTDC OK
▪ greater than 12.0°BTDC: Engine loaded
=> Switch off consumers
Throttle angle
▪ 0...5 <°: OK.
▪ greater than 5 <°: No throttle valve control unit adaptation => Page
73 Throttle cable incorrectly set => Adjust
▪ Throttle valve control unit defective => Replace
Note: The value displayed when the accelerator pedal is fully depressed
is around 80...90 <°.
As soon as a fault from the throttle valve potentiometer is recognised, a
constant substitute value of 35 <°is displayed.
Engine load
▪ 0.5...1.5 ms: OK
▪ less than 0.5 ms: Unmetered air downstream of air mass meter => Check intake
system
▪ Fuel pressure too high => check - Page 50
▪ greater than 1.50 ms Engine loaded => Switch off consumers
Engine load shown in increments of 40
▪ 800...920 rpm: OK
▪ Outside tolerance: Check idling speed => Page 49

Display Group 02 - Basic function at idling speed (engine warm, coolant temperature not below +85°C):

Read measured value block 2 ⇒ ◂ Display readout

800...920 0.5...1.5 1...3 1.8...4.0
rpm ms ms g/s
Intake air mass
▪ 1.8...4.0 g/s: OK
▪ less than 1.8 g/s Unmetered air downstream of air mass meter =>
Check
▪ greater than 4.0 g/s Engine loaded => Switch off consumers
Corrected injection period per engine cycle
▪ 1.00...3.00 ms: OK
▪ less than 1.00 ms: High proportion from tank breather system => Page
71
▪ greater than 3.00 ms: Engine loaded => Switch off consumers
Engine load, theoretical injection period per crankshaft revolution
▪ 0.5...1.50 ms: OK
▪ less than 0.5 ms: Unmetered air downstream of air mass meter => Check intake
systemProtected by copyright. Copying for private or commercial purposes, in part or in whole, is not
▪ or fuel pressure
permitted too high
unless authorised => Check
by AUDI AG. AUDI -AG Page
does not50
guarantee or accept any liability

▪ greater than 1.50 ms Engine loaded => Switch off consumers

with respect to the correctness of information in this document. Copyright by AUDI AG.

Idling speed is shown in increments of 40

▪ 800...920 rpm: OK
▪ Outside tolerance: Check idling speed => Page 49

Notes on Display Group 02:

◆ Display zone 2 shows the injection period corresponding to the intake air mass and the engine load when
idling. This value is a calculated, theoretical value which, because of the processor technology, only relates
to a single crankshaft revolution. The engine load when idling is the load created by the internal friction which
the engine has to overcome and the power required to drive the ancillaries. The intake air mass is shown
in display zone 4.
◆ Display zone 3, on the other hand, shows the injection period for a complete engine cycle, i.e. two crankshaft
revolutions.
◆ However, the value shown in display zone 3 is not approximately twice the value in display zone 2, but a
corrected actual injection period. Corrected by influencing variables such as:

1.10 - Reading measured value block: Display Groups 00 to 10 29

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Lambda control

- Fuel intake from the activated carbon canister

- Air density, air temperature

- Vehicle voltage (faster /slower opening of injectors)

◆ For example, if the engine takes in unmetered air, only the calculated value in display zone 2 (injection
period per crankshaft revolution) should change. The lambda mixture control will ensure that the actual
injection period per complete engine cycle remains at the specified value.

Display Group 03; basic function (warm engine, coolant temperature not less than +85 °C)

Read measured value block 3 ⇒ ◂ Display readout

800...920 10...14.5 80...105 ...
rpm V °C °C
Intake air temperature
▪ In the event of an open circuit, a constant temperature of -19.5°C will be
displayed as a substitute value.
▪ Check the -G42 sensor for intake air temperature =>Page 105
Coolant temperature
▪ 80...105 °C: OK
▪ less than 80 °C run engine until warm
▪ Check -G62bysensor
Protected for coolant
copyright. Copying temperature
for private =>Page
or commercial purposes, in part105
or in whole, is not
Battery voltage permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
▪ 10.000...14.500 V: OK
▪ Outside tolerance: Check voltage supply from engine control unit => Page 106
Idling speed is shown in increments of 40
▪ 800...920 rpm: OK
▪ Outside tolerance: Check idling speed => Page 49

Note on display zone 4:

It is not possible to give specified values as the display readout is heavily affected by the ambient temperature.

Display Group 04: Idling speed setting (warm engine, coolant temperature not less than +85 °C)

Read measured value block 4 ⇒ ◂ Display readout

0...5 -1.1...+1.1 -1.1...+1.1 Idling speed
<° g/s g/s
Operating status (idling, part load, enrichment, overrun)
▪ Idling: OK
▪ Other display: Check idling speed => Page 75
Idling speed air mass, learned with automatic gearbox with gear engaged D/
1/2/3
On cars with manual gearboxes, the display will always show the value "0".
Idling speed air mass learned (no gear engaged with automatic gearbox)
▪ - 1.1...+ 1.1 g/s: OK
▪ Less than - 1.1 g/s: Unmetered air downstream of throttle valve => Check
▪ higher than + 1.1 g/s: Engine loaded => Switch off consumers
▪ Intake system blocked => Check
Throttle angle
▪ 0...5<°: OK.
▪ greater than 5 <°: Throttle cable incorrectly adjusted => Adjust
▪ no adaptation, check throttle valve control unit => Page 73

30 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Notes on display zones 2 and 3:

◆ The display shows how far the learned values of the idle stabilisation have "drifted away" from the pre-
programmed mean value. With a new engine, the display will show a positive value because of the greater
friction; if the engine has been run in it will show a negative value. A value of - 1.7 g/s combined with an
excessively low value in Display Group 05, display zone 3, indicates the presence of unmetered air.
◆ The value displayed is not measured by the air mass meter but calculated from information from the throttle
valve potentiometer.

Display Group 05, idling speeding stabilisation when idling: (warm engine, coolant temp. not less than +85 °C)

Read measured value block 5 ⇒ ◂ Display readout

800...920 rpm -10...+10 1.8...4.0
rpm % g/s
Air mass
▪ 1.8...4.0 g/s: OK
▪ less than 1.8 g/s Unmetered air downstream of air mass meter =>
Check
▪ greater than 4.0 g/s Engine loaded => Switch off consumers
Idling speed control
▪ -10...+10 %: OK
Engine speed (specified)
Engine speed (actual) is shown in increments of 10
▪ 800...920 rpm: OK
▪ Outside tolerance: Check idling
Protected speed Copying
by copyright. => Page 49 or commercial purposes, in part or in whole, is not
for private
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Notes on display zone 3:

◆ During idling, the air mass requirement varies with changing load conditions, even though the engine speed
is constant.
◆ The change in air mass during idling is shown as a percentage. As soon as the change has been compen‐
sated by the idle stabilisation learning process, the mean value is restored. The amount of deviation from
the mean value depends on the extent of the load change (e.g. as a result of switching electrical consumers
on or off).
◆ The learning process proceeds in small stages each time the idling switch closes. In the event of a large
deviation, several stages are required. To do this, the accelerator pedal should be briefly pressed. at intervals
of approx. 20 seconds (throttle burst). Each time this is done, a further stage of the learning process is
performed.
◆ The "drifted" deviation then appears in Display Group 04, display zone 2. The values from the idling speed
control remain outside the tolerance if the learned values in Display Group 04, display zone 2 have reached
the stop (stop values: -:1.1 g/s and +1.1 g/s).

Notes on display zone 4:

◆ With fault (00670), throttle valve positioner: constant engine speed and air throughput of 2.8 g/s.
◆ With faults (00670/16505/16506/16507), throttle valve positioner and throttle valve potentiometer, the digital
idle stabilisation (DIS) is switched off and a constant speed of approx. 1000 rpm and an air mass of 2.8 g/
s is output.

Display Group 06, idling speeding stabilisation when idling: (warm engine, coolant temp. not less than +85°C)

Read measured value block 6 ⇒ ◂ Display readout

800...920 -10...+10 -10...+10 3...12°BTDC
rpm % %
Ignition timing
Lambda control
Idling speed control

1.10 - Reading measured value block: Display Groups 00 to 10 31

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Idling speed is shown in increments of 10

▪ 800...920 rpm: OK
▪ Outside tolerance: Check idling speed => Page 49

Notes on display zone 3:

◆ The display must fluctuate around zero. If a constant 0 is displayed, the lambda control has switched from
closed-loop control to open-loop control because there is a fault in the lambda control: Interrogate the fault
memory => Page 3 .
◆ Operating status of lambda control Display Group 21, display panel 4 =>Page 39 .

Display Group 07, lambda control and ACF system: (warm engine, coolant temperature not less than +85 °C)

Read measured value block 7 ⇒ ◂ Display readout

-10...+10 0...1 0...99 0.3...1.2
% V %
Lambda correction factor with active fuel tank breather system
▪ less than 1.00 Tank breather supplying rich mixture, lambda control
reduces the quantity injected
▪ Display 1.00: No fuel tank breather function or fuel tank breather
supplying ideal mixture (λ = 1)
▪ Greater than 1.00 Tank breather supplying lean mixture, lambda
control increases the quantity injected
Signal ratio for -N80 solenoid valve 1 for activated carbon canister
▪ Signal ratio 0 % means -N80 is closed
▪ Signal ratio 99 % means -N80 is fully open
Lambda probe voltage
▪ Voltage constantly fluctuates back and forth between - 0.1 V and 1.0 V: OK
▪ -0.1...+ 0.3 V: Large amount of residual oxygen, mixture too lean
▪ 0.7...1.0 V: Small amount of residual oxygen, mixture too rich
▪ constant 0.45...0.50 V: Lambda probe not functioning
▪ => Check lambda control - Page 65
Lambda control
▪ -10...+10 %: OK
▪ Outside tolerance: Check lambda control => Page 65

1.11 - Reading measured value block: Display Groups 08 to 99

Display Group 08: Lambda learned values (warm engine, coolant temperature not less than +85 °C)

Read measured value block 08 ⇒ ◂ Display readout

1...3 -10...+10 -8...+8 TB active
ms % % or
TB not active
"TB active" means that the solenoid valve 1 for the activated
charcoal container is pulsing (6 to 16 minutes)
"TB not active" means that solenoid valve 1 for activated char‐
coal filter is constantly closed (1 minute).
Lambda learned value at part load (multiplicative)
multiplicative means that the fault occurs throughout the entire speed range
and load range.
Lambda
Protected by copyright. Copying learned
for private value purposes,
or commercial at partinload
part or(additive)
in whole, is not
additive
permitted unless authorised by AUDImeans
AG. AUDIthat thenotfault
AG does onlyor occurs
guarantee accept anyduring
liability idling
with respect to the correctness of information in this document. Copyright by AUDI AG.

32 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Injection period
▪ 1...3 ms: OK
▪ less than 1 ms: High proportion from tank breather system => Page 71
▪ greater than 3 ms: Engine loaded => Switch off consumers

Test table, Display Group 08

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

2 low lambda learned values - Low lambda idling learned val‐ - Disappears after drive on mo‐
and ues with normal lambda -part- torway or oil change
3 load-learned values: oil may be Display Group 07, display zone 2
diluted with petrol (high petrol => Page 32
content in oil)
- Injector leaking - Check the injector=> Page
53
- Fuel pressure too high - Check fuel pressure
=>Page 50
- -N80 solenoid valve 1 for acti‐ - Check -N80 prüfen => Page
vated charcoal canister is con‐ 71
stantly open
- -G70 air mass meter defective - Check -G70 => Page 59
- Lambda probe heating defec‐ - Check lambda probe heating
tive or lambda probe dirty =>Page 68

Note on display zones 2 and 3:

Low values mean that the engine is running too rich, and the lambda control is compensating by leaning out
the mixture.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Test table, Display Group 08 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Display zone Readout on V.A.G 1551 Cause of fault Fault remedy

2 high lambda - High lambda - idling- learned val‐ - Eliminate faults
and learned values ues with lower lambda -part-load- Display Group 07, display zone 2
3 learned values: possibility of unme‐ => Page 32
tered air around intake manifold
- Injector blocked - Check injection quantity
=>Page 52
- Display zones 2 and 3 high: -G70 - Check -G70 => Page 59
air mass meter defective
- Fuel pressure too low - Check fuel pressure
=>Page 50
- Unmetered air between -G70 air - Rectify fault
mass meter and throttle valve
- Unmetered air at manifold gasket
- Lambda probe heating defective or - Check lambda probe heating
lambda probe dirty =>Page 68

Notes on display zones 2 and 3:

◆ High learned values mean that the engine is running too lean, and therefore the lambda control is compen‐
sating by enriching the mixture.
◆ If there is no voltage in the control unit, all the learned values will be reset.

Display Group 09: Lambda learned values (warm engine, coolant temperature not less than +85 °C)

Read measured value block 9 ⇒ ◂ Display readout

1.11 - Reading measured value block: Display Groups 08 to 99 33

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

rpm -10...+10 0...1.0 -10...+10

% V %
Lambda learned value when idling
▪ -10...+10 %: OK
▪ Outside tolerance: Check lambda control => Page 65
Lamba probe voltage
▪ Voltage constantly fluctuates between - 0.1...+0.3 V and 0.7...1.0 V: OK
▪ -0.1...+0.3 V: Large amount of residual oxygen, mixture too lean
▪ 0.7...1.0 V: Small amount of residual oxygen, mixture too rich
▪ constant 0.45...0.50 V: Lambda probe not functioning
▪ => Check lambda control - Page 65
Lambda control
▪ -10...+10 %: OK
▪ Outside tolerance: Check lambda control => Page 65
Engine speed is shown in increments of 10

Display Group 10, Fuel tank breather (warm engine, coolant temperature not less than +85°C)

Read measured value block 10 ⇒ ◂ Display readout

0...99 0.3...1.25 -3...+32 0.00...0.30
% %
Activated charcoal filter purging quantity (ACF)
▪ At value "0.00", nothing is supplied from the ACF system
▪ At value "0.30", 30% of the intake air mass supplied is supplied
by the ACF system
Fill level of activated charcoal filter canister
▪ At -3 % there is no petrol vapour in the activated charcoal canister.
▪ At +32 % the activated charcoal canister is full of petrol vapours.
Lambda correction factor with active fuel tank breather system
▪ less than 1.00 Tank breather supplying rich mixture, lambda control reduces the quan‐
tity injected
▪ 1.00: No fuel tank breather function or fuel tank breather supplying ideal mixture (λ=
1)
▪ Greater than 1.00 Tank breather supplying lean mixture, lambda control increases the
quantity injected
Signal ratio for -N80 solenoid valve 1 for activated carbon canister (ACF)
▪ Signal ratio 0 % means that the -N80 is closed
▪ Signal ratio 99 % means -N80 is fully open

Display Group 11 - Fuel consumption:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Read measured value block 11 ⇒ ◂ Display readout
with respect to the correctness of information in this document. Copyright by AUDI AG.

800...920 0.5...1.5 0 0.5...1.5

rpm ms km/h ltr/h
Fuel consumption:
The specified value shown on the display only relates to idling without
any additional load from ancillaries (automatic gearbox, air condi‐
tioner, alternator, power steering pump).
Driving speed
Engine load
Idling speed is shown in increments of 40

Notes on display zone 2:

◆ The maximum engine load decreases by about 10 % for every 1000 m above sea level.
◆ The maximum engine load also falls by up to 10 % at very high ambient temperatures.

34 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

◆ The values when driving at full load should not be less than the following:

- approx. 7.5 ms at 4000 rpm

- approx. 6.5 ms at 6000 rpm

Display Group 12 - Fuel consumption:

Read measured value block 12 ⇒ ◂ Display readout

800...920 10...14.5 0.5...1.5 3...12°
rpm V ltr/h BTDC
Ignition timing
▪ 3...12.0°BTDC OK
▪ greater than 12.0°BTDC: Engine loa‐
ded => Switch off consumers
Fuel consumption:
The specified value shown on the display relates only to idling without any
additional load from ancillaries (automatic gearbox, air conditioner, alternator,
power steering pump).
Battery voltage
▪ 10.000...14.500 V: OK
▪ Outside tolerance: Check supply voltage from engine control unit => Page 106
Engine speed

Display Group 13 - Knock control:

Read measured value block 13 ⇒ ◂ Display readout

0...15° 0...15° 0...15° 0...15°
crankshaft crankshaft crankshaft crankshaft
Cylinder 4 ignition timing retardation by knock control
Cylinder 3 ignition timing retardation by knock control
Cylinder 2 ignition timing retardation by knock control
Cylinder 1 ignition timing retardation by knock control

Notes on Display Group 13:

◆ The knock control is active from an engine load of greater than 40 %.

◆ At engine loads of more than 40 %, the display will show the current ignition timing retardation values. At
engine loads of less than 40 % the display will constantly show the last values used.
◆ If there is audible knocking and no perceptible ignition timing retardation, increase the engine speed to above
3500 rpm for 5 seconds in order to activate the knock sensor fault recognition (diagnosis) function.
◆ If there is a significant difference between the ignition timing retardation value for one of the cylinders and
the values for the other cylinders, the following faults are possible:

- Loose ancillaries

- Corrosion on
Protected by plug theCopying
copyright. connector
for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
- Engine damage (e.g. oil combustion because of defective piston)

Notes on Display Group 13:

◆ If the ignition timing retardation values for all the cylinders are high, the following faults are possible:

- Corrosion on plug the connector

1.11 - Reading measured value block: Display Groups 08 to 99 35

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Tightening torque (20 Nm) not OK

- Open circuit

- Knock sensor defective

- Loose ancillaries

- Poor quality fuel (less than RON 95)

Display Group 14 - Knock control:

Read measured value block 14 ⇒ ◂ Display readout

rpm ms 0...15° 0...15°
crankshaft crankshaft
Cylinder 2 ignition timing retardation by knock control
Cylinder 1 ignition timing retardation by knock control
Engine load (injection period per revolution)
Idling speed is shown in increments of 40

Note on Display Group 14:

With this display group it is possible to check the ignition timing retardation for cylinders 1 and 2 at specific
engine speeds and under specific load conditions.

Display Group 15 - Knock control:

Read measured value block 15 ⇒ ◂ Display readout

rpm ms 0...15° 0...15°
crankshaft crankshaft
Cylinder 4 ignition timing retardation by knock control
Cylinder 3 ignition timing retardation cylinder by knock control
Engine load (injection period per revolution)
Idling speed is shown in increments of 40

Notes on Display Group 15:

◆ With this display group it is possible to check the ignition timing retardation for cylinders 3 and 4 at specific
engine speeds and under specific load conditions.
◆ Causes of ignition timing retardation: Display Group 13 =>Page 35 .

Display Group 16 - Knock control: (Idling):

Read measured value block 16 ⇒ ◂ Display readout

400...1400 400...1400 400...1400 400...1400
mV mV mV mV
Knock sensor signal, cylinder 4
Knock sensor signal, cylinder 3
Knock sensor signal, cylinder 2
Knock sensor signal, cylinder 1
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

36 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Notes:
◆ If the difference between the highest and lowest knock control signals is more than 50 %, this may be due
to corrosion on the plug connector.
◆ If no faults are found as a result of the electrical check on the knock sensor, the wiring and the plug connector,
check the engine for loose ancillaries or mechanical damage. Display Group 13 =>Page 35 .
◆ At higher engine speeds and engine loads, the voltage signal displayed for the knock sensors may reach
values of up to 5.1 volts.

Display Group 17 - Catalyst heating:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Read measured value block 17 ⇒ ◂ Display readout
... ... ... ...°
rpm ms % BTDC
Ignition timing
Energy balance for catalyst heating
Engine load (injection period per revolution)
Idling speed is shown in increments of 40

Notes on Display Group 17:

◆ To bring the catalyst up to operating temperature as quickly as possible after a cold start, increase the idling
speed and retard the ignition timing. In the part load range, only the ignition timing retardation remains
activated.
◆ The rapid catalyst heating function is activated at starting temperatures of from -9 to +39 °C.
◆ The function is terminated under the following conditions:

- Engine speed greater than 4000 rpm

- Engine load greater than 7.0 ms
- Fault in fault memory for air mass meter and sensor for coolant temperature
- Speed greater than 55 km/h
- Altitude correction factor less than -20 % (Display Group 18)
◆ When the function is terminated, the display readout for the energy balance remains frozen and is reset the
next time the engine is started.

Display Group 18 - Altitude adaptation:

Read measured value block 18 ⇒ ◂ Display readout

.... ... ... -50...+10
rpm ms ms %
Altitude correction factor
▪ Outside the display limits, check the altitude sensor => Page
63
Engine load from throttle angle after altitude correction
▪ No specified value
Engine load from air mass meter
Idling speed is shown in increments of 40

Notes on Display Group 18:

◆ The engine control unit compares the load signal from the air mass meter with a load value calculated from
the throttle angle and the engine speed. The difference between the two values is the altitude correction
factor.

1.11 - Reading measured value block: Display Groups 08 to 99 37

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

◆ At an altitude of approx. 400 m above sea level and under normal weather conditions, altitude adaptation
is not necessary.

- The correction factor at sea level is approx. 0 %.

- At an altitude of 2000 m the correction factor is approx. -20 %.
◆ The altitude adaptation affects the following functions:

- Determination of starting fuel delivery

- Intake manifold-pulsation compensation
Display Group 19 up to model year 1998 - Torque reduction (automatic gearbox)

Read measured value block 19 ⇒ ◂ Display readout

760...880 1.0...2.5 1011 6...12°
rpm ms BTDC
Ignition timing
Operating status
▪ X 1 X = no gearbox intervention signal
▪ X 0 X = gearbox intervention signal
▪ X = (display has no meaning)
Engine load
Idling Protected
speed by is copyright.
shownCopying
in increments of 40 purposes, in part or in whole, is not
for private or commercial
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Notes on Display Group 19:
◆ This Display Group may be used to evaluate whether the engine control unit is receiving the gearbox inter‐
vention signal from the gearbox control unit.
◆ Because of the brief signal, the V.A.G 1551 does not always recognise the ignition timing retardation.

Display Group 19 from model year 1998, Gearshift signals

Read measured value block 19 ⇒ ◂ Display readout

760...880 1.0...2.5 1 0 1 1 6...12°
rpm ms BTDC
Ignition timing
Operating status
1 X 1 X = No signal from pressure switch for power steering
0 X 1 X = Signal from pressure switch for power steering (steering on full lock)
X 1 1 X = no gearbox intervention signal
X 0 1 X = no gearbox intervention signal
X X 1 1 = No signal from clutch pedal switch (clutch not depressed)
X X 1 0 = Signal from clutch pedal switch (clutch not depressed)
Engine load
Idling speed is shown in increments of 40

Notes on Display Group 19:

◆ The function of the power steering pressure switch is to stabilise the idling speed when the steering wheel
is on full lock (left or right).
◆ Check F88 power steering pressure switch =>Page 95 .
◆ Check gearbox intervention signal =>Page 93 .
◆ The clutch pedal switch is used to
- suppress the load change jolt
- prevent engine-speed overshoots on changing up
- Cruise control system (if there is one)

38 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

◆ Check clutch pedal switch =>Page 94 .

Display Group 20 - Operating status:

Read measured value block 20 ⇒ ◂ Display readout

... Neutral A/C - high Compr.ON
rpm Driving position ON A/C - low Compr.OFF
Air conditioner compressor
▪ Compr. ON or compr. OFF: OK
▪ For vehicles with no air conditioner, "Compr. .OFF" is al‐
ways displayed.
Air conditioner
▪ A/C high = high heating or cooling power
▪ A/C low = low heating or cooling power
▪ For vehicles with no air conditioner, "A/C - LOW" is always displayed
Selector lever position
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
▪ Neutral or. drivingpermitted
position ENGAGED
unless OKAG. AUDI AG does not guarantee or accept any liability
authorised by AUDI
▪ For cars with manual with gearboxes, the display
respect to the correctness will inalways
of information show
this document. "Driving
Copyright position
by AUDI AG.
engaged".
Engine speed is shown in increments of 10

Display Group 21 - Operating status for lambda control:

Read measured value block 21 ⇒ ◂ Display readout

... ... ... λ-control OFF
rpm ms °C λ-control ON
Lambda control
▪ λ-control OFF = lambda control off
▪ λ-control ON = lambda control on
Coolant temperature
Engine load
Idling speed is shown in increments of 40

Notes on Display Group 21:

◆ The lambda control is activated by the engine control unit in response to the engine temperature, the engine
temperature on starting and the intake air temperature.
◆ When the lambda control is switched off, the engine runs according to the map stored in the control unit.

Display Group 23 -(Adaptation of the throttle valve positioner):

Read measured value block 23 ⇒ ◂ Display readout

1 0 0 0 0 0 72...95 % 60...91 % 18...54 %
Max- stop for V60 throttle valve positioner
▪ 18...54 %: OK
▪ Outside tolerance: Perform adaptation of the throttle valve control
unit => Page 73
Emergency - running stop for V60 throttle valve positioner
▪ 60...91 %: OK
▪ Outside tolerance: Perform adaptation of the throttle valve control unit
▪ => Page 73

1.11 - Reading measured value block: Display Groups 08 to 99 39

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Min- stop for V60 throttle valve positioner

▪ 72...95 %: OK
▪ Outside tolerance: Perform adaptation of the throttle valve control unit => Page
73
Learning demand display
▪ 100000: OK
▪ Other display: Perform adaptation of the throttle valve control unit => Page 73

Display Group 24 - Knock control:

Read measured value block 24 ⇒ ◂ Display readout

rpm ms ° BTDC 5 crankshaft
Total ignition timing retardation for cylinders 1 to 4
Ignition timing
Engine load
Idling speed
Protectedis
byshown
copyright. in increments
Copying for private orof 40
commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Notes on Display Group 24: to the correctness of information in this document. Copyright by AUDI AG.
with respect

◆ As soon as symptoms of knocking are detected, the knock control must retard the ignition timing in order to
prevent engine damage.
◆ However, the ignition timing retardation does increase the exhaust gas temperature. There is a risk of the
catalytic converter overheating.
◆ Retarding the ignition timing in all the cylinders by, for example, 3 °CS has exactly the same effect as
retarding it by 12 °CS in only one of the cylinders.
◆ To avoid overheating, at full load, from a total retardation of approx. 10 °CS, enrichment takes place to
reduce the exhaust gas temperature.

Display Group 25; Boost pressure control at full load (test drive in 3rd gear at approx. 4000 rpm, coolant tem‐
perature not less than +85 °C)

Warning: The V.A.G 1551 fault reader must be operated by a second person.

Read measured value block 25 ⇒ ◂ Display readout

3.0...8.0 0.0...8.0 0.5...8.0 0...99
ms ms ms %
Signal ratio (actuation) of the N75 solenoid valve
for boost pressure control
▪ No specified value
▪ Constant 5 %: Boost pressure has open loop
control => Interrogate the fault memory
Actual engine load (regulated by boost pressure to specified -en‐
gine load)
▪ As specified engine load after correction, display zone 2 (Toler‐
ance±0.30 ms) OK
▪ Outside tolerance: Fault in boost pressure control => Page
61
Specified engine load after correction (reduced driver requirement due to knock control,
altitude adaptation and intake air temperature)
▪ 0.00...8.00 ms: OK
Specified engine load before correction (driver's requirement indicated via accelerator pedal)
▪ 3.00...8.00 ms: OK

Display Group 26 - Idling air requirement:

Read measured value block 26 ⇒ ◂ Display readout

40 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

-10...+10 -1.1...+1.1 80...105 800...920

% g/s °C rpm
Engine speed
Coolant temperature
Idling air mass (without gear engaged with automatic gearbox)
Idling speed control

Display Group 27, Load reduction by knock control at full load: (test drive in 3rd gear at approx. 4000 rpm,
coolant temperature not less than +85°C)

Warning: The V.A.G 1551 fault reader must be operated by a second person.

Read measured value block 27 ⇒ ◂ Display readout

0...5 0.5...8 .... 0...99
ms ms rpm %
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Signal or
permitted unless authorised by AUDI AG. AUDI AG does not guarantee ratio (actuation)
accept any liability of the -N75 solenoid valve for boost pressure
control
with respect to the correctness of information in this document. Copyright by AUDI AG.
▪ No specified value
▪ Constant 5 %: Boost pressure open loop control => Interrogate the
fault memory
Engine speed
Engine load after reduction
Load reduction by knock control

Display Group 66 Only for vehicles with cruise control systems (CCS): Engine idling

Read measured value block 66 ⇒ ◂ Display readout

km/h XXXX km/h XXXX
Switch settings for operating switch
0000= CCS switched on
0110= CCS switched off (switch engag‐
ed)
0010= CCS off (before the engagement
point)
0100= Fix key depressed
1000= Key Mounting pulled
Specified driving speed (the last speed to be stored is displayed) until the CCS
on the control switch switches off, switch engages in "OFF" or the engine is
stopped)
Switch settings for brake, clutch and CCS released
1000= CCS released
1111= Brake depressed (brake light switch)
1111= Brake depressed (brake light switch)
1011= Clutch depressed
Actual driving speed

Notes on Display Group 66:

If the specified values are not reached, check the cruise control system (CCS).

=> Electrical system; Repair Group 01; Technical Bulletin No. 2 Technical Bulletin No. 2

1.11 - Reading measured value block: Display Groups 08 to 99 41

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Display Group 98 - Adaptation of throttle valve control unit: Ignition switched on

Basic setting 98 ⇒ ◂ Display readout

0...5 0...5 Idling speed ADP running
V V
Adaptation status
▪ ADP running = Adaptation in progress
▪ ADP OK = Adaptation successfully completed
▪ ADP ERROR = Error has occurred in adaptation process: Check throt‐
tle valve control unit =>Page 73
Operating status
▪ Idling, part load, full load, overrun, enrichment
Potentiometer voltage for idle positioner
Throttle valve potentiometer voltage

Display Group 99 - Lambda control:

Read measured value block 99 ⇒ ◂ Display readout

... ... -10...+10 λ-control OFF
rpm °C % λ-control ON
Lambda control OFF/ON
▪ Basic setting 04: λ-Control OFF
▪ Read measured value block 08: λ-Control ON
Lambda control
Coolant temperature
Engine speed

Notes on Display Group 99:

◆ For defined fault finding, the lambda control is switched off when Display Group 99 is selected under "Basic
setting 04" and switched when it is selected in "Reading measured value block 08".
◆ When function 04 "Basic setting" is left, the lambda control is automatically re-activated.
◆ By pressing the keys 4 and 8 on the V.A.G 1551, it is possible to switch back and forth between function 04
"Basic setting" and function 08 "Reading measured value block".

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

42 01 - Self-diagnosis
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

24 - Mixture preparation, Injection

1 - Repairing the Motronic fuel injection system

1.1 - Repairing the Motronic fuel injection system

1.2 - Safety precautions

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Warning: permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

The fuel system is under pressure! Before loosening hose connections or opening the test connection, place
with respect to the correctness of information in this document. Copyright by AUDI AG.

a cloth around the connection point. Then dissipate the pressure by carefully pulling off the hose or removing
the plug.

To prevent injuries to persons and/or damage to the fuel injection and ignition system, the following must be
noted:

◆ Do not touch or disconnect ignition wiring when the engine is running or turning at starter speed.
◆ Only detach or attach the wiring in the injection and ignition system, including measuring instrument leads,
when the ignition is switched off.

◆ To operate the engine at starting speed without actually starting it (for example, in order to test compression),
unplug the connector from the power output stage for the ignition coils and also the plug connectors from
the injectors. After completing the work, interrogate the fault memory.
◆ Always switch off the ignition before washing the engine.
◆ Always switch off the ignition before connecting or disconnecting the battery, otherwise the engine control
unit may be damaged.

1.3 - Rules for cleanliness

When working on the fuel supply/injection system, pay careful attention to the following "5 rules":

◆ Thoroughly clean all unions and the adjacent areas before disconnecting.
◆ Place removed parts on a clean surface and cover. Do not use fluffy cloths!
◆ Carefully cover or seal open components if repairs cannot be carried out immediately.
◆ Only install clean components:
Only remove replacement parts from packaging immediately prior to installation.
Do not use parts that have been stored loose (e.g. in tool boxes etc.).
◆ When the system is open:
Do not work with compressed air if this can be avoided.
Do not move vehicle unless absolutely necessary.

1.4 - Technical data

Engine code AGU

1.1 - Repairing the Motronic fuel injection system 43

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Idling speed Manual gearbox 860 rpm (air conditioner on and off)
Speed not adjustable- it is controlled by the idle sta‐ Automatic gearbox (driving position neutral, air condi‐
bilisation tioner off) 860 rpm
Automatic gearbox (driving position neutral, air condi‐
tioner on) 880 rpm
Automatic gearbox (driving position engaged, air condi‐
tioner off) 820 rpm
Automatic gearbox (driving position engaged, air condi‐
tioner on) 820 rpm
Engine speed limitation 6800 rpm
by disconnecting the injectors
Fuel pressure at idling speed Vacuum hose connected approx. 2.5 bar
Vacuum hose detached approx. 3 bar
Holding pressure after 10 minutes at least 1.5 bar
Injectors Spray pattern Two hole nozzle
Injection quantity (30 s) 85...105 ml
Resistance (room tempera‐ 13...18 ω
ture)1)

1) If the engine is warm, the resistance increase by approx. 4...6 ω.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

44 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

1.5 - Overview of fitting locations

1 Solenoid valve 1 for activated carbon canister (N80)

2 4-pin connector
◆ For lambda probe and lambda probe heating
◆ Located on underside of car on right hand side
3 Engine control unit (J220)
4 Ignition coils
◆ Cylinder 1 (N)
◆ Cylinder 2 (N128)
◆ Cylinder 3 (N158)
◆ Cylinder 4 (N163)
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
5 Solenoid
permitted valve
unless authorised for boost
by AUDI AG. AUDIpressure
AG does not control
guarantee or(N75)
accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

1.5 - Overview of fitting locations 45

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

6 Air mass meter (G70)

7 Output stage for ignition coils (N122)
◆ at the air cleaner

Note:

In certain vehicles, the output stage may be installed in the plenum chamber on the wiper motor.

8 Sensor for coolant temperature (G62)

9 Engine speed sensor (G28)
10 Injectors
◆ Cylinder 1 (N30)
◆ Cylinder 2 (N31)
◆ Cylinder 3 (N32)
◆ Cylinder 4 (N33)
11 Knock sensor 2 (G66)

46 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

12 3-pin connector
from left
◆ For knock sensor 1
◆ For engine speed sensor
◆ For knock sensor 2
13 Knock sensor 1 (G61)
14 Intake air temperature sensor (G42)
15 Throttle valve control unit (J338)
16 Hall sensor (G40)

1.6 - Wiring and component check with test box V.A.G 1598/22

Notes:
◆ Use the V.A.G 1526 hand multimeter or the V.A.G 1715 multimeter and the diode test lamp V.A.G 1527 for
the checks.
◆ To connect the test devices to the 1598/22 test box, always use auxiliary cables from adapter set V.A.G
1594.
◆ The contact numbers of the plugs and the socket numbers in the test box are identical.
◆ After re-connecting the engine control unit, adapt the throttle valve control unit.

1.5 - Overview of fitting locations 47

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

=> Page 73

Warning:
To prevent damage to the electronic components, switch to the respective measuring range before connecting
the measuring cable and observe the test conditions.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

- With the ignition switched off, pull the plug connector off control unit.
- -> Connect the V.A.G 1598/22 test box to the connector on the wiring harness.
- Carry out the test as described in the relevant repair instructions.

1.7 - Replacing the engine control unit

Note:

When the engine control unit is disconnected, the learned values are erased but the contents of the fault memory
remain intact.

Removing the engine control unit

- Switch the ignition off.

- Unscrew the windscreen wiper arms and remove the plenum chamber cover.

48 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Note:

To remove the cover, first disconnect the hoses and plugs for the spray nozzles.

- -> Press the retainer tab on the bracket to the side using a screwdriver, then pull out the engine control unit
towards the front.
- Release the connector latches and pull of the control unit connectors.

Installing the engine control unit

Installation is performed in the reverse sequence.

Note:

In the first learning phase, during the basic setting operation for the engine, irregular idling and slight jolting
during normal driving are possible.

After installing the engine control unit, carry out the following operations:

- Perform the encoding of the new engine control unit => Page 19
- Perform adaptation of the throttle valve control unit => Page 73
- Adaptation of the engine control unit to the immobilizer control unit.

=> Electrical system; Repair Group 01; Immobilizer self-diagnosis; adaptation after replacement of the engine
control unit Immobilizer self-diagnosis adaptation after replacement of the engine control unit

1.8 - Checking idling speed

Test conditions
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
• No leaks in exhaust system. permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

• Coolant temperature at least 80 °C

with respect to the correctness of information in this document. Copyright by AUDI AG.

• Throttle valve in idle position

=> 4-Cylinder Engine, mechanical components; Repair group 20; fuel supply system; repair throttle mechanism.
fuel supply system repair throttle mechanism.

• Electrical consumers switched off (radiator fan must not run during the check)
• Air conditioner switched off
• Pressure gauge not connected.
• Selector lever in position P or N.

Checking idling speed

Notes:

◆ The idling speed cannot be adjusted.

◆ The idling speed should be tested during the basic setting of the engine.

- Interrogate the fault memory => Page 3 . No faults must be stored, if necessary, rectify fault, erase fault
memory, switch off and re-start engine, perform test drive and interrogate the fault memory again as a check.
- Leave engine idling.
- Switch off the air conditioner.
- Switch off the rear window heating.
- Place the selector lever in P or N position (vehicles with automatic gearboxes).

1.7 - Replacing the engine control unit 49

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Warning:
The electric radiator fan should not be running.

- Select the function "Reading measured value block" (function 08) and Display Group 5
=>Page 31 .

-> Display readout:

Read measured value block 5
1 2 3 4

- Read off idling speed (actual) from display zone 1.

- Read off idling speed (specified) from display zone 2.

- Press the ⇒key.

- Press keys 0 and 6 for the function "End of output" and confirm entry with the Q key.
- If the value does not match the specification, interrogate the fault memory again =>Seite 3 .

If the idling speed is too high or too low and there are no faults recorded in the fault memory, carry out the
following tests:
• Check the idling switch => Page 75 .
• Check the throttle valve control unit =>Page 73 .
• Unmetered air in intake system
• Solenoid valve for activated carbon canister constantly open.

1.9 - Checking fuel pressure regulator and holding pressure

Test conditions
• Check that fuel pump relay is OK => Page 56 .
• Fuel pump OK.
• Fuel filter OK.
• Battery voltage OK.

Note:
The fuel pressure regulator regulates the fuel pressure according to the intake manifold pressure at the throttle
valve unit.

Warning:
The fuel system is under pressure! Before opening the system place a cloth around the connection point. Then
release pressure by carefully loosening the connection.

- Briefly open the fuel tank filler cap (to release pressure).
- Cover the pressurised screw connection with a cloth.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

50 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Pull the fuel supply hose (white marking) off the fuel supply pipe.
- Connect the V.A.G 1318 pressure gauge to the fuel supply pipe using adapters 1318/8, 1318/9 and 1318/17.
- -> Open the cut-off valves in the pressure gauge. The lever points in the direction of flow.
- Start the engine and run at idling speed.
- Measure the fuel pressure.

Specified value: approx. 2.5 bar.

- -> Pull the vacuum hose off the fuel pressure regulator. The fuel pressure should increase to approx. 3.0
bar.
- Switch the ignition off.
- Check tightness and holding pressure by watching the gauge indicator fall.
- After 10 minutes the remaining pressure should be at least 1.5 bar.

If the holding pressure drops below 1.5 bar:

- Start the engine and run at idling speed.

- -> Allow the pressure to build up, then switch off the ignition. At the same time close the cut-off valve on the
pressure gauge (valve handle at right angles to direction of flow).
- Observe the pressure drop on the gauge.

If the pressure now does not drop:

- Check the fuel pump non return valve.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

1.9 - Checking fuel pressure regulator and holding pressure 51

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

However, if the pressure drops again:

- -> Open the cut-off valve on the V.A.GProtected
1318 bypressure gauge
copyright. Copying (valve
for private handle points
or commercial purposes,in direction
in part ofisflow).
or in whole, not
- Start the engine and run at idling speed.
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- Allow the pressure to build up, then switch off the ignition. At the same time, pinch the return hose (with blue
with respect to the correctness of information in this document. Copyright by AUDI AG.

marking) firmly together.

If the pressure now does not drop:

- Replace the fuel pressure regulator.

If the pressure drops again:

- Check the pipe connections, O-rings on the fuel manifold and injectors for leaks.
- Check the pressure gauge for leaks.

Note:
Before removing the pressure gauge, release the fuel pressure by opening the cut-off valve. Hold a container
over the connection while doing so.

1.10 - Checking injection quantity, leak tightness and spray pattern of injectors

Test conditions
• Check that the fuel pressure is OK => Page 50 .

- Disconnect the vacuum hose from the fuel pressure regulator.

- Disconnect the connectors from all the injectors.
- Unclip the wiring harness from the cable guide and remove.
- Unbolt the fuel manifold from the intake manifold and pull it upwards and off the intake manifold together
with the injectors.

- Place the injector which is to be tested in a measuring glass from the V.A.G 1602 injection quantity tester.

52 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- -> Connect one of the injector contacts to the engine earth using a test cable and crocodile clip from the
V.A.G 1594 test.
- Connect the second injector contact to positive using remote control V.A.G 1348/3 A, adapter cable V.A.G
1348/3- 2 and an auxiliary cable.
- Start the final control diagnosis => Page 15 . The fuel pump must be running.
- Check injectors for leaks (visual check). When the fuel pump is running, only 1 or 2 drops a minute should
escape from each injector.
- If the fuel loss is greater than this, switch off the fuel pump (terminate final control diagnosis) and replace
the faulty injector.

- If necessary, re-start the final control diagnosis.

Note:

The final control diagnosis cannot be re started until the ignition has been switched off briefly.

- Activate the V.A.G 1348/3 A remote control for 30 seconds.

- Perform measurements on all injectors.
- Once all four injectors have been actuated, place the measuring glasses on a level surface.

Specified value: 85...105 ml

- If the measured value for one or more of the injectors is outside the tolerance range, switch off the fuel pump
(terminate final control diagnosis) and replace the defective injector.
- If the measured values for all the injectors are outside the tolerance range, check the fuel pressure => Page
50 .

Note:
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

When checking the injection quantity, also check the spray pattern. The spray pattern should be the same for
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
all the injectors.

The installation of the fuel manifold together with injectors is performed in the reverse sequence. The following
points should be noted when installing:

• Replace the O-rings at all opened connections. (When replacing the front O-ring, never pull the plastic cap
off the injector head. - Pull the O-ring off over the plastic cap.)
• Moisten the O-rings with clean engine oil.
• Make sure that the injectors are installed in the correct positions.
• Check to make sure that the retainer clamps are properly seated.

1.11 - Checking the injectors

Electrical checks on injectors

- Remove the plug connector from the injector which is to be tested.

1.10 - Checking injection quantity, leak tightness and spray pattern of injectors 53
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- -> Measure the resistance between the injector contacts using the V.A.G 1526 hand held multimeter.

Specified value: 13...18 ω.

If the engine is warm, the resistance will be approx. 4...6 ω.

- If the measured value is not as specified, replace the injector.

Checking the power supply to the injectors

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Test conditions

• Fuse for injectors OK.

- Remove the plug connector from the injector which is to be tested.

- -> Connect the V.A.G 1527 diode test lamp between contact 1 and the engine earth.
- Operate the starter for a few seconds (the engine can be allowed to start).

The diode test lamp should light up.

- If the diode test lamp lights up, test the actuation of the injectors.

If the diode test lamp does not light up:

- Check the wiring from contact 1 via the injector fuse to the fuel pump relay for continuity and, if necessary.
rectify open circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

54 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Checking injector actuation

- Remove the plug connector from the injector which is toAGbe tested.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI does not guarantee or accept any liability
- -> Connect the V.A.G 1527 with diode
respect totest lamp between
the correctness contact
of information 2 and Copyright
in this document. the battery's positive terminal.
by AUDI AG.
- Operate the starter briefly (the engine may start briefly).

The diode test lamp should flash.

Note:
Diode test lamps with a low current consumption do not go out completely between the flashing pulses, but
continue to glow slightly and become much brighter during the flashing pulses.

1.11 - Checking the injectors 55

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the diode test lamp does not flash:

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- -> Check the wiring between contact 2 on the connector for the injector in question and the engine control
unit for continuity or a short to positive.

Contact 2 on plug the Test box V.A.G 1598/22

connector for injector Contact
1 73
2 80
3 58
4 65

- If necessary, rectify open circuit or short circuit.

- If the wiring is OK, replace the engine control unit => Page 48 .

1.12 Protected
- Checking fuel
by copyright. pump
Copying relay
for private and purposes,
or commercial actuation
in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Note:

-> The fuel pump relay is located in the central electrics in the left hand footwell, relay position 4.

56 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Checking the -J17 fuel pump relay

- Remove the storage bin in the front left hand footwell.

- -> Pull fuse 28 out of the fuse holder and connect the V.A.G 1527 diode test lamp between the earth and
one of the two contacts for fuse 28.
- Operate the starter briefly.

The fuel pump relay should pick up (can be felt and heard) and the diode test lamp should light up.

If the diode test lamp does not light, although the fuel pump relay picks up:

- Repeat the test on the other contact on fuse 28.

If the diode test lamp still does not light up:

- -> Check the wiring between contact 23 at relay position 4 and fuse 28 for continuity and, if necessary, rectify
open circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

- If no open circuit is detected, replace the fuel pump relay.

If the fuel pump relay does not pick up:

- Check the actuation of the fuel pump relay => Page 57 .

Checking the power supply and actuation of the fuel pump relay

- Remove the -J17 fuel pump relay from the central electrics, relay position 4.

Checking
Protected the powerCopying
by copyright. supply
for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- Switch on the
with respect to theignition.
correctness of information in this document. Copyright by AUDI AG.

1.12 - Checking fuel pump relay and actuation 57

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- -> In sequence, connect the V.A.G 1526 hand held multimeter to contact 19 (positive) and earth and contact
17 (positive) and the earth in the relay panel.

Specified value: approx. battery voltage in each case

- If the values are not as specified, rectify the open circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

Checking actuation
- -> Connect the V.A.G 1527 diode test lamp to contact 16 (earth) and positive.
- The diode test lamp should light up and remain lit when the starter is operated.

Note:
Diode test lamps with a low current consumption do not go out completely but continue to glow faintly until the
starter is operated.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

58 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the diode test lamp does not light up, check the wiring as follows:
- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

- Connect the hand-held multimeter between contact 16 on the relay panel and socket 4 on the test box, then
check the wiring for an open circuit.
- If necessary, rectify open circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
- If there is no open circuit and the diode test lamp does not light, replace the engine control unit => Page
48 .
- If the actuation and power supply for the fuel pump relay and the wiring are OK, replace the fuel pump relay.
- Replace fuse 28.

1.13 - Checking the air mass meter

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permittedChecking operation
unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
- Select the function "Reading measured value block" (function 08) and Display Group 2
=>Page 29 .

-> Display readout

Read measured value block 2
1 2 3 4

Display zone 4 will show the intake air mass (grams per second).
Specified value: 1.8...4.0 g/s

- If the specified values are not achieved or if there is a fault relating to the air mass meter in the fault memory,
check the power supply to the air mass meter => Page 59 .

Checking the power supply to the air mass meter

- Check the fuse for the air mass meter.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

- -> If the fuse is OK, connect the V.A.G 1527 diode test lamp between contact 3 on the connector and the
engine earth.
- Operate the starter briefly (the engine may start briefly).

The diode test lamp should light up.

- -> If the diode test lamp does not light up, check the wiring from contact 3 on the connector via the fuse to
the fuel pump relay for an open circuit or short to earth and rectify if necessary.

1.12 - Checking fuel pump relay and actuation 59

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

- If the fuse and the wiring are OK but the diode test lamp still does not light up, check the fuel pump relay =>
Page 56 .
- If the power supply is OK, check the signal line => Page 60 .

Checking signal line for the air mass meter

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- -> Check the wiring from the connector on the air mass meter...

- -> to the engine control unit for an open circuit or short to positive or earth and rectify if necessary:

Connector for -G70 air Test box V.A.G 1598/22

mass meter Contact
1 02 (earth)
2 12 Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
4 13 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

- If the power supply and the wiring are OK, replace the -G70 air mass meter.

60 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

2 - Checking the boost pressure system

2.1 - Checking the boost pressure system

2.2 - Checking the boost pressure control

- Select the function "Reading measured value block" (function 08) and Display Group 25
=>Page 40 .

-> Display readout:

Read measured value block 25
7.40 ms 7.10 ms 7.05 ms
67 %

Warning:
The V.A.G 1551 must be operated by a second person.

- Perform a test drive at full throttle at approx. 4000 rpm.

- measured value block 25
Read
7.40 ms 7.10 ms 7.05 ms 67 %

-> Observe the display in display zone 4 (duty cycle of solenoid valve for boost pressure control).

Specified value: 5...95 %

If the specified value is not achieved, change the engine speed until the duty cycle is within the specified range.

- measured value block 25

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Read permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
7.40 ms 7.10 ms 7.05 ms 67 %
with respect to the correctness of information in this document. Copyright by AUDI AG.

-> Observe the display in display zone 2 (corrected specified -engine load)

Specified value: 0.00...8.00 ms

- measured value block 25

Read
7.40 ms 7.10 ms 7.05 ms 67 %

-> Observe the display in display zone 3 (actual-engine load)

Specified value: Identical with corrected specified engine load in display zone 2 (tolerance ± 0.3 ms)

If the actual engine load is outside the tolerance, this may be due to one of the following faults:

◆ Electrical fault in solenoid valve for the boost pressure control.

◆ Charge pressure control hoses disconnected, leaking or blocked.
◆ -N75 solenoid valve for boost pressure control blocked.
◆ Leak between turbocharger and intake manifold.
◆ Actuation mechanism (linkage, shaft) for the by-pass valve stiff or jamming.
◆ Turbocharger defective (turbine jammed by foreign body).

2.3 - Checking solenoid valve for boost pressure control

Checking operation

- Pull the hoses off the -N75 solenoid valve for boost pressure control
=> Fitting locations -Overview - Page 45 .
- Connect auxiliary hose.

2.1 - Checking the boost pressure system 61

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Start the final control diagnosis and actuate the -N75 solenoid valve for boost pressure control =>Page
15 .

-> Display readout:

Final control diagnosis
-N75 solenoid valve for boost pressure
control

The valve should click...

...and should open and close (check by blowing into the auxiliary hose).

If the valve does not click:

- Check the solenoid valve for boost pressure control electrically => Page 62 .

When there is no electrical signal, the long connection is closed.

If the solenoid valve clicks, but does not open and close properly:
- Replace the solenoid valve for boost pressure control (N75).

Electrical check on solenoid valve for boost pressure control (N75).

- Unplug the connector from the valve

=> Fitting locations - Overview - Page 45 .
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- -> Connect the V.A.G
with respect 1526 hand
to the correctness heldinmultimeter
of information for resistance
this document. Copyright by AUDI AG.measurement to the valve.

Specified value: 25...35 ω.

If the specified value is not achieved:

- Replace the solenoid valve for boost pressure control (N75).

If the specified value is achieved:

- Check the power supply from the solenoid valve for boost pressure control => Page 62 .

Check the power supply to the solenoid valve for boost pressure control (N75).

62 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- -> Connect the V.A.G 1526 hand held multimeter for voltage measurement to contact 1 of the connector
and the earth.
- Operate the starter briefly (the engine may start briefly).

Specified value: approx. battery voltage.

If the specified value is not achieved:

- Check the wiring from contact 1 on the connector via the fuse to the fuel pump relay for an open circuit or
short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
If the specified value is achieved:
- Check the actuation for the solenoid valve for boost pressure control => Page 63 .

Checking the actuation of the solenoid valve for the boost pressure control (N75)
- Unplug the connector from the solenoid valve (N75) and connect the V.A.G 1527 diode test lamp between
connector contacts 1 and 2.
- Start the final control diagnosis and actuate the N75 solenoid valve for boost pressure control =>Page
15 .

The diode test lamp should start flashing.

- If diode test lamp does not flash or if the lamp is lit continuously. Check the wiring.
- Connect the V.A.G 1598/22 test box to theProtected
wiringbyharness for the
copyright. Copying for engine control unit
private or commercial purposes, in part or in whole, is not
=>Page 47 . permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

-> The following wiring should be checked for a short to positive or negative and an open circuit:

2-pin connector on the Test box V.A.G 1598/22

wiring harness contact. contact.
2 64

- If necessary, rectify open circuit or short circuit.

2.4 - Checking altitude sensor

The altitude sensor signal influences:

◆ The boost pressure control

The boost pressure control prevents the turbocharger from over revving when the altitude increases and
consequently the air density decreases.
A decrease in air density (lower air pressure) causes the turbocharger to increase its charging rate (higher
speed) to produce the required boost pressure.

2.3 - Checking solenoid valve for boost pressure control 63

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

This results in a higher charge air temperature and an increased risk of engine knock. To avoid this, the
boost pressure is limited.

◆ Composition of mixture when starting the engine

The richness of the starting mixture is determined by mapped characteristics stored in the engine control
unit and is leaned out according to a correction factor determined by the altitude sensor as the altitude
increases (lower air density as the air pressure decreases).

- Switch on the ignition.

- Select the function "Reading measured value block" (function 08) and Display Group 18
=>Page 40 .

-> Display readout:

Read measured value block 18
1 2 3 4

Note:
The altitude correction factor is determined by the air pressure (barometer reading) and by the altitude of the
workshop.
Observe display zone 4.

Display in Air pressure

display zone 4 in mbar
0% 1013 mbar
(sea level)
-6 % 950 mbar
(altitude 500 m)
-10 % 900 mbar
(altitude
Protected by copyright. 1000
Copying for privatem)
or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
-20 % 800 mbar
with respect to the correctness of information in this document. Copyright by AUDI AG.
(altitude 2000 m)
-30 % 700 mbar
(altitude 3000 m)

If an implausible value appears in display zone 4:

- -> Pull off connector on the sensor.

- Switch on the ignition.
- -> Connect the V.A.G 1526 hand held multimeter for voltage measurement between the following connectors
contacts:

3-pin connector on the wiring harness, Specified value

contact
1+3 approx. 5 V

64 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

2+3 approx. 5 V

If the specified values are not achieved:

- Switch the ignition off.

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

-> The following wiring should be checked for a short to positive or negative and an open circuit:

3-pin connector on the Test box V.A.G 1598/22

wiring harness contact. contact.
1 61
2 62
3 67

- If necessary, rectify open circuit or short circuit.

If no wiring fault is detected:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
- Replace the altitude sensor permitted
(F96). unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- If an implausible value is still displayed after the replacement of the altitude sensor, replace the engine
with respect to the correctness of information in this document. Copyright by AUDI AG.

control unit => Page 48 .

3 - Checking the lambda control

3.1 - Checking the lambda control

The lambda probe compares the oxygen content in the air with the residual oxygen content in the exhaust gas
and sends a voltage signal to the control unit.

The voltage signal for "Mixture too rich" (low residual oxygen) is approx. 0.7...1.1 V (relative to the reference
earth).

The voltage signal for "Mixture too lean" (high residual oxygen) is approx. -0.1...+0.3 V (relative to the reference
earth).

During the transition from "rich" to "lean" and vice versa (λ = 1.0), there is a voltage jump from 0....1.1 V to
-0.1...+0.3 V or vice versa.

Due to the sharp voltage jump, the lambda control cannot maintain a constant ideal mixture composition cor‐
responding toλ= 1.0. The system fluctuates continuously between "slightly too lean" and "slightly too rich".

2.4 - Checking altitude sensor 65

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the voltage does not change or only changes slowly, the following faults are possible:

◆ Slots or holes in probe head are blocked.

◆ Lambda probe was subjected to excessive thermal stress.
◆ Contact resistance in signal wiring or reference earth wire.
◆ Lambda probe too cold; lambda probe heating not working.
◆ Lambda control switched off (control unit has detected a fault in the injection system). =>Interrogate the fault
memory and reading measured value block, Display Group 21.
◆ Lambda probe damaged by contact spray or similar product. (The contact spray is drawn through the fine
cavities in the electrical wiring as a result of thermal fluctuations and capillary effect.)
◆ Lambda probe damaged by silicone vapours. (The engine draws in traces of any silicone based sealants
that may have been used. These silicone components do not burn and damage the lambda probe.)

3.2 - Poor performance after cold start

Test conditions

• No faults relating to lambda control stored, if necessary rectify any faults and erase the fault memory.

If faults occur after a cold start, check whether the problem arises before or after the lambda control cuts in.

Warning:
The V.A.G 1551 must be operated by a second person.

Checking the vehicle under cold start conditions:

- Take the vehicle for a test drive.

- Select the function "Reading measured value block" (function 08) and Display Group 21
=>Page 39 .

-> Display readout:

Read measured value block 21
860 rpm 1.15 ms 13.7 5C
l-Control OFF

- Check display in display zone 4.

Specified value: λ-Control OFF (lambda control not active)

If the engine running problems occur before the lambda control cuts in, the following faults are possible:

◆ Carbon deposits on the inlet valves.

◆ Unmetered air in intake system.
◆ Fuel supply system defective.

At a lambda probe temperature of approx 300°C, the lambda control kicks in. The time it takes for this temper‐
ature to be reached is influenced by the following factors:

◆ Ambient temperature (summer or winter)

◆ Operating status after starting.
◆ Operation of lambda probe heating.

-> Display readout:

Read measured value block 21
860 rpm 1.15 ms 34.2 5C
l-Control ON
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- Check display in display zone 4. with respect to the correctness of information in this document. Copyright by AUDI AG.

Specified value: λ-Control ON (lambda control active)

66 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the engine running problems only occur after the lambda control sets in:

- Check operation => Page 67

3.3 - Checking operation

- Select the function "Reading measured value block" (function 08) and Display Group 03
=>Page 30 .

-> Display readout:

Read measured value block 3
1 2 3 4

Do not proceed with the test until the coolant temperature shown in display zone 3 has reached at least 80 °C.

- Press the C key.

- Press keys 0 and 7 for "Display group number 07" and confirm entry by pressing the Q key.

-> Display readout:

Read measured value block 7
1 2 3 4

Display zone 2 will show the voltage of the lambda probe signal.

- If the probe voltage fluctuates very slowly, check the lambda probe heating => Page 68 .
- If the display shows a constant lambda probe voltage reading of 0.45...0.50 V, this means there is an open
circuit in the signal wiring, check the wiring => Page 69 .
- If the display shows a constant voltage reading of 0.0...+0.3 V (mixture too lean), this means that the lambda
control has reached the control stop in the "enrich" direction, but the lambda probe is still registering "Mixture
too lean".
- If the display shows a constant voltage reading of 0.7...1.0 V (mixture too rich), this means that the lambda
control has reached the control stop in the "lean" direction, but the lambda probe is still registering "Mixture
too rich".
- Press the C key.

If the lambda probe is functioning properly, check the lambda learned values.

- Press keys 0 and 8 for "Display group number 08"and confirm entry by pressing the Q key.

-> Display readout

Read measured value block 8
2ms -0.7 % -0.5 % TB
active
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
The mixture adaptation system has a learning ability, i.e. the lambda control can recognise differences between
engines (injector nozzle delivery, cylinder compression, fuel pressure, etc.) and compensates by adjusting the
pre programmed basic injection periods mapped in the control unit. The injection periods are extended or
reduced until a mixture of λ = 1 is achieved. The difference between the actual injection period and the basic
injection time programmed in the map is given %.

◆ Positive learned value (+...%): Pre programmed basic injection period too short, actual injection period ...%
longer, so that λ = 1 is achieved.
◆ Negative learning value (-...%): Pre programmed basic injection period too long, actual injection period ...%
shorter, so that λ = 1 is achieved.

Specified values: => Page 32 .

3.2 - Poor performance after cold start 67

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

3.4 - Checking lambda probe heating

- The lambda probe heating circuit is monitored by the self diagnosis system.
- Interrogate the fault memory => Page 3 .

Electrical check on lambda probe heating

- Unplug the 4 pin connector on the underside of the vehicle to the right of the lambda probe (G39).
- -> Measure the resistance between contacts 1 and 2 on the lambda probe connector using the V.A.G 1526
hand held multimeter.

Specified value at room temperature 1...5ω.

Note:

With even a small temperature increase, the resistance will increase sharply.

If an open circuit is detected:

- Replace the lambda probe.

If no open circuit is detected:

- Check the power supply for the lambda probe heating => Page 68 .

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Checking the power supply for the lambda probe heating

- Check the fuse for the lambda probe heating.

If the fuse is OK:

- -> Connect the V.A.G 1527 diode test lamp between contact 1 on the wiring harness connector and the
engine earth.
- Operate the starter briefly (the engine may start briefly).

68 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

The diode test lamp should light up.

If the diode test lamp does not light up.

- -> Check the wiring from contact 1 in the wiring harness connector to fuse for an open circuit or short to
earth and rectify if necessary.

If the power supply is OK:

- Connect the V.A.G 1598/22 test box to the wiring harness to the engine control unit =>Page 47 .

- -> Test the following wiring for continuity or a short circuit.

Connector on the wiring Test box V.A.G 1598/22

harness plug Contact
2 27

- If the fuse and the wiring are OK but the diode test lamp still does not light up, check the fuel pump relay =>
Page 56 .

3.5 - Checking lambda probe signal line and actuation

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

3.4 - Checking lambda probe heating 69

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Note:

The lambda probe signal is monitored by the self diagnosis system.

- Interrogate the fault memory => Page 3 .

- If a fault in the lambda probe has been registered and the lambda probe heating is OK, unplug the lambda
probe connector.
- -> Test voltage by connecting the V.A.G 1526 hand held multimeter (measuring range 2 V) between contacts
3 and 4 of plug on the wiring harness.
- Switch on the ignition.

Specified value: 450 ± 50 mV.

If the specified value is not achieved:

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .

- -> Check the following wiring for an open circuit and short circuit to positive or earth and rectify if necessary.

Lambda probe, bank 1 -G39

Connector on the wiring Test box V.A.G 1598/22 or

harness plug control unit connector -J220
3 25
4 26

- If the wiring is OK, replace the engine control unit => Page 48 .

3.6 - Removing and installing the lambda probe

Removing
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
- Unplug the lambda probe connector.
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- Unscrew the lambda probe using V.A.G 3337/9.
with respect to the correctness of information in this document. Copyright by AUDI AG.

When installing, note the following points:

70 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Notes:
◆ Tightening torque 50 Nm.
◆ The screw thread on the lambda probe is coated with a special paste (hot screw paste). This paste must
not be allowed to penetrate the openings on the probe.

4 - Checking the fuel tank breather system

4.1 - Checking the fuel tank breather system

4.2 - Checking the solenoid valve

Protected 1 forCopying
by copyright. the for
activated carbon
private or commercial canister
purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Leak test

When there is no electrical signal, the solenoid valve remains closed.

- Disconnect the hoses from the solenoid valve for the activated carbon canister (N80).
- Attach the connector to the solenoid valve.
- Start the final control diagnosis and select the solenoid valve for the activated carbon canister (N80)
=>Page 15 .
- During the final control diagnosis, blow into solenoid valve to check whether it opens and closes properly.
If necessary, fit a new solenoid valve.

Electrical check on the -N80 solenoid valve

- Unplug the connector on the ACF valve.

- Measure the resistance between the contacts on the valve using the V.A.G 1526 hand held multimeter.

Specified value: 22...30 ω.

If the specified value is not achieved:

- Replace the -N80 solenoid valve for the activated carbon canister.

Checking the power supply to the ACF valve

Note:
The ACF valve receives its power supply via the fuel pump relay.

Test conditions

• Fuse for ACF valve OK

3.6 - Removing and installing the lambda probe 71

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Unplug the connector on the ACF valve.

- -> Connect the V.A.G 1527 diode test lamp between contact 1 on the connector and the engine earth.
- Actuate the starter.

The diode test lamp should light up.

If the diode test lamp does not light up:

- Check the wiring from contact 1 via the fuse to the fuel pump relay for continuity, repair if necessary.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

- If the wiring is OK, check the fuel pump relay => Page 56 .

Check the actuation of the ACF valve

- -> Connect the V.A.G 1527 diode test lamp between contact 2 and contact 1 (positive) in the connector.
- Start the final control diagnosis and select the solenoid valve for the activated carbon canister (N80)
=>Page 15 .

The diode test lamp should start flashing.

If the diode test lamp does not flash or is continuously lit:

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

72 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the diode test lamp is continuously lit:

- -> Test for the line from contact 2 on the ACF valve connector and socket 15 on the test box for a short to
earth.

If the diode test lamp does not flash:

- Test the line from contact 2 on the ACF valve connector to contact 15 on the test box for continuity and for
a short to positive.
- If necessary, rectify a short circuit to earth or open circuit.
- If no short circuit or open circuit is found, replace the engine control unit
=> Page 48 .

5 - Checking the throttle valve control unit - vehicles without CCS

5.1 - Checking the throttle valve control unit - vehicles without CCS

The idle stabilisation is integrated in the throttle valve control unit.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
The box facing the cable pulley contains the following
permitted components
unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
(this box must not be opened): with respect to the correctness of information in this document. Copyright by AUDI AG.

- -G69 throttle valve potentiometer.

- -G127 sensor for throttle valve positioner.
- -F60 idling switch.
- -V60 throttle valve positioner (electric motor) .

None of the potentiometers and switches may be adjusted mechanically. The settings are performed as part
of the basic setting (function 04) using the V.A.G 1551 or 1552 fault reader.

5.2 - Adaptation of the throttle valve control unit without CCS

The idle stabilisation requires the engine control unit to know the stop positions of the throttle valve positioner
(V60) and the potentiometer characteristics of the throttle valve positioner sensor (G127) and throttle valv5e
potentiometer (G69).

The learning process (adaptation) is necessary if:

◆ The power supply to the engine control unit has been interrupted (e.g. the battery disconnected) .
◆ The throttle valve control unit was replaced.
◆ The engine control unit was replaced.

The learning process (adaptation process) is performed:

◆ Automatically if the ignition is switched on once for at least 6 seconds without actuating the starter or the
accelerator pedal.
◆ By initiating the basic setting (function 04) Display Group 98 with the engine stopped.

Test conditions

• No fault stored in fault memory

=> Page 3 , Interrogate the fault memory

- Connect the V.A.G 1551 fault reader (V.A.G 1552) and select the engine electronics control unit with the
"Address word" 01. During this, the ignition must be switched on.
(Connecting the fault reader and selecting the control unit for the engine electronics => Page 2 .)

-> Display readout:

4.2 - Checking the solenoid valve 1 for the activated carbon canister 73
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Rapid data transfer HELP

Select function XX

- Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with the Q key.

-> Display readout:

Basic setting HELP
Enter display group number XXX

- Press keys 0, 9 and 8 for "Display group number 98" and confirm entry with the Q key.

-> Display readout

System in basic setting 98
x.xxx V x.xxx V Idle ADP.
running

When the Q key is pressed, the throttle valve positioner moves to min., - max. - and five intermediate positions.
The control unit records the voltage reading for each position in its non volatile memory. This process takes no
more than 10 seconds. The throttle valve then remains in the start position for a brief period before closing.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
-> with
Display
respect readout:
to the correctness of information in this document. Copyright by AUDI AG.
System in basic setting 98
x.xxx V x.xxx V Idle ADP. OK

______________________________________________

-> If one of the following messages appears on the display, the adaptation was terminated.
Basic setting 98
X,XXX V X.XXX V Idle ADP. not OK

-
Basic setting 98
X,XXX V X.XXX V Idle ADP. running

Terminate adaptation by pressing the ⇒ key.

Basic setting 98
X,XXX V X.XXX V Idle ERROR

Function is unknown or cannot

be performed at present!

- Interrogate the fault memory

No - fault detected

-> If no faults are recognised, check whether the idling switch opens and closes when the accelerator pedal
is operated. Check idling switch => Page 75 .

-
Idling switch does not open
Short to earth

-> If one of these faults is displayed, check whether the idling switch opens and closes when the accelerator
pedal is pressed, check the idling switch => Page 75 .

Idling switch does not close

Open circuit

-
Voltage supply
Signal too low

-> If this fault is displayed, check the power supply to the engine control unit (voltage at terminal 30 on engine
control unit has dropped below 10 V).
-
-G127 sensor for throttle valve positioner
⇒
Signal too low or too high

74 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

-> If one of the following faults is displayed, check the -G127 sensor for the throttle valve positioner => Page
76 .

-G69 throttle valve potentiometer

Signal too low or too high

-G127 sensor for throttle valve

positioner
Implausible signal

Note:

If the basic setting of the control unit is interrupted, the cause could be one of the following:

◆ The throttle valve does not reach the mechanical idle stop due to contamination.
◆ Throttle cable incorrectly adjusted.
◆ The battery voltage is too low.
◆ The throttle valve control unit or wiring is defective.

After an interruption, the fault "Basic setting not completed, fault in basic setting" is stored in the fault memory.
The next time the ignition is switched on, the basic setting is automatically performed again.

- Terminate the engine basic setting by pressing the ⇒ key.

- Press keys 0 and 6 for the function "End data transfer" and confirm the entry with the Q key.

5.3 - Checking the idling switch without CCS

- Switch on the ignition.
- Select the function "Reading measured value block" (function 08) and Display Group 98
=>Page 42 .

-> Display readout:

Read measured value block 98
X,XXX V X,XXX V
Idling ................

Display zone 3 should read "Idling".

- Slowly open throttle valve.

-> Display readout:

Read measured value block 98
X,XXX V X,XXX V Part
load ................. Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Display zone 3 should read "Part load".

- Slowly close throttle valve again.

-> Display readout:

Read measured value block 98
X,XXX V X,XXX V
Idling ..................

Display zone 3 should read "Idling".

If the specified value "Idling" is not achieved:

- Switch the ignition off.

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

5.2 - Adaptation of the throttle valve control unit without CCS 75

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Measure the resistance between contacts 67 and 69 using the V.A.G 1526 hand held multimeter.

Specified value: continuity (throttle valve closed)

- Open the throttle valve slightly.

Specified value: No continuity (idling speed switch should open).

If the specified value is not achieved:

- Check the wiring for short circuit to positive or earth and open circuit.

8-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
3 69
7 67

- If necessary, rectify open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
If no wiring faults are detected:
- Inspect throttle valve for dirt or stiffness and, if necessary, clean.
- Perform adaptation of the throttle valve control unit => Page 73 .
- If it is not possible to start the adaptation or successfully conclude it:
- Detach the throttle cable.
- Repeat the adaptation of the throttle valve control unit once more => Page 73 .
- If it is once again not possible to start or conclude successfully the adaptation of the throttle valve control
unit, replace the throttle valve control unit. Perform the adaptation again.
=> Page 73 .

5.4 - Checking the throttle valve potentiometer without CCS

The throttle valve potentiometer (G69) informs the engine control unit of the position of the throttle valve.
Test conditions
• Check the throttle cable setting
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
=> 4-cylinder engine,
with respect mechanical
to the correctnesscomponents;
of information in thisRepair
document.Group
Copyright20 by AUDI AG.

- Switch on the ignition.

- Select the function "Reading measured value block" (function 08) and Display Group 01
=>Page 28

-> Display readout:

Read measured value block 1
0 rpm 0.00 ms 4 -5 xxxBDTC

- Check display in display zone 3.

Read measured value block 1

0 rpm 0.00 ms 4 -5 xxxBDTC

-> Specified value: 0...5 <°

- Slowly depress accelerator pedal.

Read measured value block 1

0 rpm 0.00 ms 86 -5 xxxBDTC

76 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

-> Specified value: The readout in display zone 3 should increase steadily until it reaches 85...90 <° (with
accelerator pedal fully depressed).

If either the initial or the final specification is not achieved:

- Check the power supply.

If the display does not change or only changes irregularly:

- Check the wiring

=> Page 77 .

Check the power supply to the throttle valve control unit

- Unplug the connector from the throttle valve control unit.

- -> Connect the V.A.G 1526 hand held multimeter for voltage measurement to contact 4 of the connector
and the earth.
- Switch on the ignition.

Specified value: approx 5 V

Check wiring

- Switch the ignition off.

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

The following wiring should be checked for a short to positive or negative and an open circuit:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

8-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
4 62
5 75

5.4 - Checking the throttle valve potentiometer without CCS 77

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

7 67

- If necessary, rectify open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

If no wiring fault is detected:

- Test sensor for throttle valve positioner

=> Page 78 .

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
5.5 - Checking the sensor for throttle valve positioner without
permitted unless CCS
authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

The sensor for the throttle valve positioner (G127) informs the engine control unit of the position of the throttle
valve positioner (V60).

- Start the engine.

- Select the function "Reading measured value block" (function 08) and Display Group 98
=>Page 42 .

-> Display readout:

Read measured value block 98
4.420 V 3.880 V Idle
ADP. OK

- Check display in display zone 2.

Specified value: 0.500...4.900 V.

If the specified value is not achieved:

- Switch the ignition off.

- -> Unplug the connector from the throttle valve control unit.
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

The following wiring should be checked for a short to positive or negative and an open circuit:

8-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
4 62
7 67
8 74

- If necessary, rectify open circuit or short circuit.

78 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
If no wiring fault is detected:
- Check throttle valve positioner => Page 79 .

5.6 - Checking throttle valve positioner without CCS

The throttle valve positioner (V60) is an electric motor. When the engine is idling, it actuates the throttle valve
via a gear mechanism in order to control the idling speed.
- Switch on the ignition.
- Select "Basic setting" (function 04) and Display Group 98 => Page 42 .

-> Display readout

Basic setting 98
4.420 V 3.880 V Idle
ADP. running

When the Q key is pressed, the throttle valve positioner moves to the min. - and max. - stop (visible and audible
at the throttle valve control unit).
If the throttle valve positioner does not move:

- Switch the ignition off.

- -> Unplug the connector from the throttle valve control unit.
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

The following wiring should be checked for a short to positive or negative and an open circuit:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

8-pin connector on the Test box V.A.G 1598/22

wiring harness contact socket
1 66

5.5 - Checking the sensor for throttle valve positioner without CCS 79
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

2 59

- If necessary, rectify open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

If no wiring fault is detected:

- Replace the throttle valve control unit (J338).

6 - Checking the throttle valve control unit - vehicles with CCS

6.1 - Checking the throttle valve control unit - vehicles with CCS

The idle stabilisation is integrated in the throttle valve control unit.

The box facing the cable pulley contains the following components
(this box must not be opened):

- -G69 throttle valve potentiometer.

- -G127 sensor for throttle valve positioner.
- -F60 idling switch.
- -V60 throttle valve positioner (electric motor)

None of the potentiometers and switches may be adjusted mechanically. The settings are performed as part
of the basic setting (function 04) using the V.A.G 1551 or 1552 fault reader.

6.2 - Adaptation of the throttle valve control unit with CCS

The idle stabilisation requires the engine control unit to know the stop positions of the throttle valve positioner
(V60) and the potentiometer characteristics of the throttle valve positioner sensor (G127) and throttle valve
potentiometer (G69).

The learning process (adaptation) is necessary if:

◆ The power supply to the engine control unit has been interrupted (e.g. the battery disconnected) .
◆ The throttle valve control unit was replaced.
◆ The engine control unit was replaced.

The learning process (adaptation process) is performed:

◆ Automatically if the ignition is switched on once for at least 6 seconds without actuating the starter or the
accelerator pedal.
◆ By initiating the basic setting (function 04) Display Group 98 with the engine stopped.

Test conditions

• No fault stored in fault memory

=> Page 3 . Interrogate the fault memory.

- Connect the V.A.G 1551 fault reader (V.A.G 1552) and select the engine electronics control unit with the
"Address word"Protected
01. During this, the ignition must be switched on.
by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
(Connecting the fault reader
with respect to theand selecting
correctness the control
of information unit for
in this document. the engine
Copyright by AUDI AG.electronics => Page 2 .)

-> Display readout

Rapid data transfer HELP
Select function XX

80 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Press keys 0 and 4 for the function "Introduction of basic setting" and confirm entry with the Q key.

-> Display readout:

Basic setting HELP
Enter display group number XXX

- Press keys 0, 9 and 8 for "Display group number 98" and confirm entry with the Q key.

-> Display readout

System in basic setting 98
x.xxx V x.xxx V Idle ADP.
running

When the Q key is pressed, the throttle valve positioner moves to min., - max. - and five intermediate positions.
The control unit records the voltage reading for each position in its non volatile memory. This process takes no
more than 10 seconds. The throttle valve then remains in the start position for a brief period before closing.

-> Display readout:

System in basic setting 98
x.xxx V x.xxx V Idle ADP. OK

______________________________________________

-> If one of the following messages appears on the display, the adaptation was terminated.
Basic setting 98
X,XXX V X.XXX V Idle ADP. not OK

-
Basic setting 98
X,XXX V X.XXX V Idle ADP. running

Terminate adaptation by pressing the ⇒ key.

Basic setting 98
X,XXX V X.XXX V Idle ERROR

Function is unknown or cannot

be performed at present

- Interrogate the fault memory

No - fault detected

-> If no faults are recognised, check whether the idling speed switch opens and closes when the accelerator
pedal is operated, check the idling switch with CCS.
=> Page 82 .

-
Idling switch does not open
Short to earth

-> If one of these faults is displayed, check whether the idling speed switch opens and closes when the
accelerator pedal is operated. Test idling switch with CCS.
=> Page 82 .

Idling switch does not close

Open circuit

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
-
Voltage permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
supply
with respect to the correctness of information in this document. Copyright by AUDI AG.
Signal too low

-> If this fault is displayed, check the power supply to the engine control unit (voltage at terminal 30 on engine
control unit has dropped below 10 V).
-
-G127 sensor for throttle valve positioner
⇒
Signal too low or too high

6.2 - Adaptation of the throttle valve control unit with CCS 81

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

-> If the following faults are displayed, check the -G127 sensor for the throttle valve positioner => Page
83 .

-G69 throttle valve potentiometer

Signal too low or too high

-G127 sensor for throttle valve

positioner
Implausible signal

Note:

If the basic setting of the control unit is interrupted, the cause could be one of the following:

◆ The throttle valve does not reach the mechanical idle stop due to contamination.
◆ Throttle cable incorrectly adjusted.
◆ The battery voltage is too low.
◆ The throttle valve control unit or wiring is defective.

After an interruption, the fault "Basic setting not completed, fault in basic setting" is stored in the fault memory.
The next time the ignition is switched on, the basic setting is automatically performed again.

- Terminate the engine basic setting by pressing the ⇒ key.

- Press keys 0 and 6 for the function "End data transfer" and confirm the entry with the Q key.

6.3 - Checking the idling switch with CCS

- Switch on the ignition.
- Select the function "Reading measured value block" (function 08) and Display Group 98
=>Page 42 .

-> Display readout:

Read measured value block 98
X,XXX V X,XXX V
Idling ................

Display zone 3 should read "Idling".

- Slowly open throttle valve.

-> Display readout:

Read measured value block 98
X,XXX V X,XXX V Part
load .................

Display zone 3 should read "Part load".

- Slowly close the throttle valve again.

-> Display readout:

Read measured value block 98
X,XXX V X,XXX V
Idling ................

Display zone 3 should read "Idling".

If the specified value "Idling" is not achieved: Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
- Switch the ignition off. with respect to the correctness of information in this document. Copyright by AUDI AG.
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

82 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Measure the resistance between contacts 67 and 69 using the V.A.G 1526 hand held multimeter.

Specified value: continuity (throttle valve closed)

- Open the throttle valve slightly.

Specified value: No continuity (idling speed switch should open)

If the specified value is not achieved:

- Check the wiring for short circuit to positive or earth and open circuit.

8-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
6 69
2 67

- If necessary, rectify open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
If no wiring faults are detected:
- Inspect throttle valve for dirt or stiffness and clean if necessary.
- Perform adaptation of the throttle valve control unit => Page 80 .
- If it is not possible to start the adaptation or successfully conclude it:
- Detach the throttle cable.
- Repeat the adaptation of the throttle valve control unit once more => Page 80 .
- If it is once again not possible to start or conclude successfully the adaptation of the throttle valve control
unit, replace the throttle valve control unit. Perform the adaptation again.
=> Page 80

6.4 - Checking the throttle valve potentiometer withCopying

Protected by copyright. CCSfor private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

The throttle valve potentiometer (G69) informs the engine control unit of the position of the throttle valve.
Test conditions
• Check the throttle cable setting

=> 4-cylinder engine, mechanical components; Repair Group 20

- Switch on the ignition.
- Select the function "Reading measured value block" (function 08) and Display Group 01
=>Page 28 .

-> Display readout:

Read measured value block 1
0 rpm 0.00 ms 4 -5 xxxBDTC

- Check display in display zone 3.

Read measured value block 1

0 rpm 0.00 ms 4 -5 xxxBDTC

-> Specified value: 0...5 <°

- Slowly depress accelerator pedal.

Read measured value block 1

0 rpm 0.00 ms 86 -5 xxxBDTC

6.3 - Checking the idling switch with CCS 83

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

-> Specified value: The readout in display zone 3 should increase steadily until it reaches 85...90 <° (with
accelerator pedal fully depressed).

If either the initial or the final specification is not achieved:

- Check the power supply.

If the display does not change or only changes irregularly:

- Check the wiring.

=> Page 84

Check the power supply to the throttle valve control unit

- Unplug the connector from the throttle valve control unit.

- -> Connect the V.A.G 1526 hand held multimeter for voltage measurement to contact 5 of the and to the
earth.
- Switch on the ignition. Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Specified value: approx. 5 V.

Check wiring.

- Switch the ignition off.

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

The following wiring should be checked for a short to positive or negative and an open circuit:

8-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
4 75
5 62

84 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

2 67

- If necessary, rectify open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

If no wiring fault is detected:

- Test sensor for throttle valve positioner

=> Page 85 .

6.5 - Checking the sensor for the throttle valve positioner with CCS

The sensor for the throttle valve positioner (G127) informs the engine control unit of the position of the throttle
valve positioner (V60).

- Start the engine.

- Select the function "Reading measured value block" (function 08) and Display Group 98
=>Page 42

-> Display readout:

Read measured value block 98
4.420 V 3.880 V
Idle ADP. OK

- Check display in display zone 2.

Specified value: 0.500...4.900 V.

If the specified value is not achieved:

- Switch the ignition off.

- -> Unplug the connector from the throttle valve control unit.
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

The following wiring should be checked for a short to positive or negative and an open circuit:
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
8-pin connector on the Test box V.A.G 1598/22
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
wiring harness contact contact
with respect to the correctness of information in this document. Copyright by AUDI AG.

5 62
2 67
1 74

- If necessary, rectify open circuit or short circuit.

6.4 - Checking the throttle valve potentiometer with CCS 85

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
If no wiring fault is detected:
- Check throttle valve positioner => Page 86 .

6.6 - Checking the throttle valve positioner with CCS

The throttle valve positioner (V60) is an electric motor. When the engine is idling, it actuates the throttle valve
via a gear mechanism in order to control the idling speed.
- Switch on the ignition.
- Select "Basic setting" (function 04) and Display Group 98 => Page 42 .

-> Display readout:

Basic setting 98
4.420 V 3.880 V Idle
ADP. running

When the Q key is pressed, the throttle valve positioner moves to the min. - and max. -stop (visible and audible
at the throttle valve control unit).
If the throttle valve positioner does not move:

- Switch the ignition off.

- -> Unplug the connector from the throttle valve control unit.
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

The following wiring should be checked for a short to positive or negative and an open circuit:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

8-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
7 59

86 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

8 66

- If necessary, rectify open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

If no wiring fault is detected:

- Replace the throttle valve control unit (J338).

7 - Cheocking auxiliary signals

7.1 - Cheocking auxiliary signals

7.2 - Checking air conditioner compressor shut-off

The air conditioner compressor signal informs the engine control unit that the compressor will be switched on
in 140 ms.

The engine control unit can send a signal via the same wire to shut off the air conditioner compressor.

The engine control unit will shut off the air conditioner compressor in the following cases:

◆ On accelerating sharply from low speeds for approx 4 s (recognition from change in angle on throttle valve
potentiometer and speed signal). Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
◆ At full load in 1st gear for a maximum of 12 seconds.
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
◆ If the throttle valve control unit is defective and the engine
with respect speed
to the is less
correctness than 1500
of information rpm. Copyright by AUDI AG.
in this document.
◆ After each engine start for approx 6 seconds.
◆ During the learning process for idle stabilisation for approx 15 seconds.

Test conditions

• Air conditioner functioning properly.

• No faults recorded in fault memory of engine control unit.
• Passenger compartment temperature warmer than +15 °C.

- Connect the V.A.G. 1551 fault reader => Page 2 .

- Start the engine.
- Select the function "Reading measured value block" (function 08) and Display Group 20 % Page.

-> Display readout:

Read measured value block 20
860 rpm Neutral A/C-Low
Compr. OFF

- Observe readout in display zone 4.

Specified value: Compr. OFF

- Switch on the air conditioner by pressing the "Auto" key. The compressor must run.

Specification for display zone 3: A/C - high

Specification for display zone 4: Compr. ON

- Abruptly floor the accelerator and release again (brief burst of throttle).

6.6 - Checking the throttle valve positioner with CCS 87

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

When the accelerator is floored quickly, the readout in display zone 4 should jump from "ON" to "OFF" for a
few seconds (compressor shut off during acceleration).

If the display is not as described:

- Switch the ignition off.
- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .
- Test for an open circuit and short to earth or positive in the wiring from contact 8 on engine control unit to
the air conditioner.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
- If there are no faults in the wiring, check the operation of air conditioner.

=> Air conditioner; Repair Group 01; Self diagnosis for air conditioner Self diagnosis for air conditioner

7.3 - Checking the engine speed adaptation by switching on the air conditioner

Notes:
◆ When the air conditioner is switched on, a positive signal is sent to contact 10 on the engine control unit.
◆ The signal causes the engine control unit to maintain a constant idling speed despite the varying power
requirements of the air conditioner.

Test conditions
• Air conditioner functioning properly.
• No faults recorded in air conditioner fault memory.
• Passenger compartment temperature warmer than +15 °C.

- Connect the V.A.G. 1551 fault reader => Page 2 .

- Start the engine (operating temperature).
- Switch off the rear window heating.
- Select the function "Reading measured value block" (function 08) and Display Group 20 % Page.

-> Display readout:

Read measured value block 20
860 rpm Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Neutral A/C-Low
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Compr. OFF
with respect to the correctness of information in this document. Copyright by AUDI AG.

88 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Display zone 1: Idling speed

Display zone 3: Signal from air conditioner
Display zone 4: Signal from air conditioner compressor
- Switch on the air conditioner by pressing the "Auto" key. The compressor must run.

Specification for display zone 4: "Compr. ON"

Apart from a brief drop in revs, the idling speed should remain constant.
If the idling speed does not remain constant, check whether the engine control unit is receiving the signal from
the air conditioner.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Specification for display zone 3: A/C - high

Specification for display zone 4: "Compr. ON"

If the specified value is not achieved:

- Switch the ignition off.
- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- Test for an open circuit and short to earth or positive in wiring from the contact 10 on engine control unit to
the air conditioner.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
- If there are no faults in the wiring, check the operation of air conditioner.

=> Air conditioner; Repair Group 01; Self diagnosis for air conditioner Self diagnosis for air conditioner

7.4 - Checking selector lever position on automatic gearbox

Note:
In selector lever positions P and N, the J226 relay for the starter inhibitor and reversing light switches contact
22 on the engine control unit to earth.
- Connect the V.A.G. 1551 fault reader => Page 2 .
- Switch on the ignition.

7.3 - Checking the engine speed adaptation by switching on the air conditioner 89
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Select the function "Reading measured value block" (function 08) and Display Group 20 % Page.

-> Display readout:

Read measured value block 20
860 rpm Neutral A/C-Low
Compr. OFF

Observe readout in display zone 2.

Specified value: "Neutral" (selector lever in P or N)

- Operate the footbrake and engage a gear.

-> Display readout:

Read measured value block 20
860 rpm Neutral A/C-Low
Compr. OFF

Observe readout in display zone 2.

Specified value: Driving position "ON"

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

If the display is not as described:

- Switch the ignition off.

- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .
- Connect the diode test lamp between contact 3 (terminal 30) and contact 22.
- The diode test lamp should go out when a gear is engaged.
- Move selector lever to position P or N.

The diode test lamp should light up.

If the diode test lamp does not light up:

- Test for an open circuit and short to positive or earth in the wiring between gearbox control unit and contact
22 on engine control unit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

- If there are no faults in the wiring, test the multi function switch.

90 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

=> Automatic gearbox 01M; Repair Group 01; Gearbox electrical check Gearbox electrical check

7.5 - Checking engine speed signal

The engine speed signal is required for the rev counter, air conditioner and automatic gearbox.
However, since the signal cannot be read in the form in which it is generated by the engine speed sensor (G28),
it has to be processed beforehand by the engine control unit.
Determine the engine speed, as follows:
- Connect the V.A.G 1551 fault reader
=> Page 2 and perform "Automatic Test Sequence 00".

No faults relating to a "missing engine speed signal" should be stored in any of the control units.
If one of the control units indicates a fault:
- Determine open circuit or or short circuit between engine control unit and the control unit concerned.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

7.6 - Checking throttle valve positioner

Notes:
◆ This signal is used by the control unit for the automatic gearbox in conjunction with the engine speed for
various things including for calculating the engine
Protected by copyright. torque
Copying for private oroutput.
commercial purposes, in part or in whole, is not
◆ The signal is output by contact 7 on the engine control unit.
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

- Connect the V.A.G. 1551 fault reader => Page 2 .

- Start the self diagnosis of the gearbox control unit.

=> Automatic Gearbox 01M; Repair Group 01; Perform self diagnosis. Perform self diagnosis.
- If the gearbox control unit displays fault 00638 "Engine/gearbox electrical connection 2", interrogate the
engine control unit's fault memory => Page 3 .

If the engine control unit has recorded a fault relating to the throttle valve potentiometer:
- Rectify this fault first. (In this case the fault recorded in the gearbox control unit is then only a secondary
fault.)

7.4 - Checking selector lever position on automatic gearbox 91

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If no fault relating to the throttle valve potentiometer is displayed:

- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .
- Check the wiring from contact 7 of the engine control unit (test box V.A.G 1598/22) to the gearbox control
unit for an open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

7.7 - Checking the speed signal

Notes:
◆ The speed signal is produced by the -G68 road speed sensor and processed in the dash panel insert.
◆ The processed signal goes to contact 20 on the engine control unit and is used for idling speed stabilisation
and for the damping of load change jolts when changing gear.

- Connect the V.A.G. 1551 fault reader

Protected => Page
by copyright. Copying 2for .private or commercial purposes, in part or in whole, is not

- Switch on the ignition. permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
- Select the function "Reading measured value block" (function 08) and Display Group 11.

-> Display readout:

Read measured value block 11
860 rpm 1.15 ms 0 km/h
0.84 l/h

Warning:
The V.A.G 1551 must be operated by a second person.

- Take the vehicle for a test drive.

- Observe readout in display zone 3.

-> Specified value: The current road speed should be displayed (compare with speedometer).
Read measured value block 11
2430 rpm 5.60 ms 45 km/h
3.38 l/h

If the road speed is not displayed:

92 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- Check the wiring between contact 20 on the test box and the dash panel insert for continuity or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

If no fault is detected in the wire:

- Establish which electrical "consumers" (e.g. radio, automatic gearbox, air conditioner etc.) are using the
speed signal, disconnect them one by one from the dash panel insert, then keep repeating the test until the
cause of the problem has been identified.

7.8 - Checking the gearbox intervention signal when changing gear

Notes: Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
◆ This signal is produced by the automatic
with respect gearbox control
to the correctness unit when
of information the gearCopyright
in this document. is changed.
enables by AUDI AG.The signal
the ignition timing to be briefly retarded by varying amounts (torque reduction) depending on the road speed
and engine speed in order to reduce shifting jolt.
◆ Because the signal is very brief the V.A.G. 1551 does not always recognise the command to retard the
ignition timing.

- Connect the V.A.G. 1551 fault reader => Page 2 .

- Select the function "Reading measured value block" (function 08) and Display Group 19
=> Page 38 .
- Take the vehicle for a test drive.

Warning:
The V.A.G 1551 must be operated by a second person.

-> Display readout:

Read measured value block 19
1 2 3 4

- Display zone 3 shows the gearshift signal supplied by the gearbox when changing gear.

up to model year 1998:

Specified value: X 1 X = no gearbox intervention.

Specified value: X 0 X = gearbox intervention.

from model year 1998:

Specified value: X 1 X X = no gearbox intervention.

Specified value: X 0 X X = gearbox intervention.
Value: X = (no meaning).

- Display zone 4 shows the effective ignition timing (actual value).

7.7 - Checking the speed signal 93

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- The wiring to the gearbox control unit is monitored by the gearbox self diagnosis (fault code 00545).
- If no torque reduction is displayed on the measured value block during a gearshift, or if fault code 00545
appears (in the gearbox control unit):
- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .
- Check the wiring from contact 23 on the engine control unit to the gearbox control unit for an open circuit or
short circuit

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

7.9 - Checking clutch pedal switch

This signal prevents engine speed fluctuations and load change jolts when the clutch is disengaged and is also
required for the cruise control system.
- Read measured value block (function 08) and selected display group 19 => Page 38 .

-> Display readout:

Read measured value block 19
1 2 3 4

- Check display in display zone 3.

Specified value: X X X 1 = Clutch pedal not depressed

- Depress clutch pedal.

Specified value: X X X 0 = Clutch pedal depressed

Value:
ProtectedX
by = (no meaning)
copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
If the
with display is correctness
respect to the not as described,
of information incheck the power
this document. Copyrightsupply => Page 94 .
by AUDI AG.

Checking the power supply

- Unplug the connector from clutch pedal switch.
- Switch on the ignition.
- Connect the V.A.G 1527 diode test lamp between contact 1 (positive) on the connector and the engine earth.

Specified value: The diode test lamp should light up.

94 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the diode test lamp does not light up:

- If the diode test lamp does not light up, check the wiring from contact 1 on the connector via the fuse to the
fuel pump relay for an open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

If the specified value is achieved, check the actuation.

=>Page 95 .

Check the actuation of the clutch pedal switch

- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .
- Check the wiring from contact 9 on the engine control unit to the connector on the clutch pedal switch contact
2 for an open circuit or short circuit.

=> Current Flow Diagrams, ElectricalProtected

Fault by Finding and Fitting Locations binder
copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

7.10 - Checking the power steering pressure switch

The function of the power steering pressure switch is to stabilise the idling speed when the steering wheel is
on full lock (left or right).

- Start the engine.

- Read measured value block (function 08) and selected display group 19 => Page 38 .

-> Display readout:

Read measured value block 19
1 2 3 4

- Check display in display zone 3.

Specified value: 1 X X X = No Signal from the pressure switch for power steering

- Turn the steering fully to the left or right.

7.9 - Checking clutch pedal switch 95

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Specified value: 0 X X X = Signal from the pressure switch for power steering

Value: X = (no meaning)

If the display is not as described, check the wiring => Page 96 .

Check wiring

- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .
- Check the following wiring for an open circuit and short circuit to positive or earth.

Connector on the wiring Test box V.A.G 1598/22

harness plug socket
1 49
2 14

- If necessary, rectify open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

7.11 - Checking the Motronic system/ABS/gearbox data exchange (CAN bus)

- Read fault memory from ABS control unit and gearbox control unit.

If a fault relating to the CAN bus appears on the display:

- Switch the ignition off.

96 24 - Mixture preparation, Injection

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- -> Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=> Page 47 .
- Check the wiring from contacts 29 and 41 on the engine control unit to the gearbox control unit and ABS
control unit for an open circuit or short circuit.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

- If the wiring is OK, tentatively replace ABS control unit, gearbox control unit or engine control unit.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

7.11 - Checking the Motronic system/ABS/gearbox data exchange (CAN bus) 97

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

28 - Ignition system

1 - Checking ignition system

1.1 - Checking ignition system

1.2 - Safety precautions

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
To prevent injuries to persons and/or damage to the fuel injection and ignition system, the following must be
noted:

◆ Do not touch or disconnect ignition wiring when the engine is running or turning at starter speed.
◆ Only detach or attach the wiring in the injection and ignition system, including measuring instrument leads,
when the ignition is switched off.
◆ To operate the engine at starting speed without actually starting it (for example, to check the compression),
unplug the connector from the power output stage for the ignition coils and the connector from the injectors.
After completing the work, interrogate the fault memory.

Warning:
Before disconnecting battery, obtain the radio code for radios fitted with anti theft coding.
Always switch off the ignition before connecting or disconnecting the battery, otherwise the engine control unit
may be damaged.

1.3 - Technical data

Engine codes AGU

Ignition timing is determined by the control unit
Ignition timing cannot be adjusted
Ignition system Single coil ignition system with four ignition coils
Spark plugs Tightening torque: 30 Nm.
Spark plug connectors Resistance approx. 2 kω
Ignition sequence 1-3-4-2
Engine speed limitation by Motronic system 6800 ± 40 rpmin
Cut off speed

1.4 - Checking ignition coils

Identify an inoperative or misfiring cylinder as follows:

- Unplug the connectors from the injectors in sequence with the engine running, and observe how the engine
runs.

or

- Compare the spark plugs of all cylinders with each other and check for soot on the electrodes.

98 28 - Ignition system
 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the defective cylinder has been identified:

- Connect a hand held multimeter for resistance measurement to the spark plug connector.

Specified value: approx. 2 kω

If the specified value is not achieved:

- Replace the spark plug connector.

If the specified value is achieved:

- Replace the spark plug of the defective cylinder with one from another cylinder.

If the fault moves with the spark plug:

- Replace the spark plug.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
If the fault remains in the same cylinder:
with respect to the correctness of information in this document. Copyright by AUDI AG.

- Replace the ignition coil from the defective cylinder with one from another cylinder.

If the fault moves with the ignition coil:

- Replace the ignition coil.

If the fault remains in the same cylinder:

Check the earth connection for the ignition coil
- Unplug the connector from the ignition coil.

- -> Check the earth connection from contact 4a on the 3 pin connector to the engine earth for an open circuit
or short to positive.
- If necessary, rectify open circuit or short circuit.

If the earth connection is OK:

1.4 - Checking ignition coils 99

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Check the power supply to the ignition coil

- -> Connect the multimeter for voltage measurement to contact 15 on the connector and the earth.
- Switch on the ignition.

Specified value: approx battery voltage

If the specified value is not achieved:

- Check the wiring.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

If the specified value is achieved:

Checking actuation

- Remove the 4-pin connector from the power output stage => Overview of fitting locations - Page 45 .

- Switch on the ignition.

- -> Connect the V.A.G 1527 diode test lamp to the following contacts on the connector:

4-pin connector on the wiring Specified value

harness contact
1 + earth Diode test lamp should
2 + earth light up
3 + earth
4 + earth

If the specified values are not achieved:

- Switch the ignition off.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

100 28 - Ignition system

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- -> Unplug the 3 pin connector on the relevant ignition coil.

- Check the wiring between the power output stage and contact 1 on the relevant ignition coil connector for
an open circuit.

Contact on 4 pin connector Contact 1 on 3 pin connec‐

for output stage tor for ignition coil
Connector Cylinder
1 1
2 3
3 4
4 2

- If necessary, rectify open circuit or short circuit.

1.5 - Checking output stages for ignition coils

Checking actuation of power output stages

- Pull the connectors off all four injectors.

Note:

It is important to ensure that no fuel is injected during the test, as this would damage the catalytic converter.
Therefore, the connectors on the injectors must be unplugged.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

- Remove the 5-pin connector from the power output stage => Overview of fitting locations - Page 45 .
- -> Connect the V.A.G 1527 diode test lamp to the following contacts on the power output stage connector:

- Actuate the starter for a few seconds.

1.4 - Checking ignition coils 101

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

5-pin connector on the wiring Specified value

harness contact
1 + earth Diode test lamp should
2 + earth flash (brief impulse)
4 + earth
5 + earth

If the specified values are not achieved:

- Switch the ignition off.

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- -> Check the wiring from the 5 pin connector on the power output stage ...
- .... to the engine control unit for an open circuit and short to positive or earth. Check the earth.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

Contact on 5 pin connec‐ Contact on test box V.A.G

tor on the power output 1598/22
stage
1 77
2 70
3 2
4 78
5 71

- If necessary, rectify open circuit or short circuit.

If no fault is detected in the wiring:

- Connect the 5 pin connector to the power output stage.

- Pull the 4 pin connector off the power output stage.

- Connect the V.A.G 1527 diode test lamp to battery positive (+) and to one of the contacts on the 4 pin
connector on the power output stage.

102 28 - Ignition system

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Operate the starter for a few seconds.

The diode test lamp should start flashing.

- Carry out the test with all 4 contacts on the power output stage.

The diode test lamp should flash each time.

If the diode test lamp does not flash when testing one or more of the contacts:

- Replace the power output stage.

1.6 - Checking the intake air temperature sensor

- Connect the V.A.G. 1551 fault reader => Page 2 .
- Switch on the ignition (engine cold).
- Select the function "Reading measured value block" (function 08) and Display Group 03.

-> Display readout:

Read measured value block 3
1 2 3 4

- Check display in display zone 4.

Specified value: approx the same as the ambient temperature

If there is an open circuit in the wiring to the sensor, a substitute value of 19.5 °C will be displayed.

If display zone 4 shows an implausible value:

- Switch the ignition off.

- -> Pull off the connector on the sensor => Fitting locations Overview, Page 45 .
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- -> Check the wiring from the connector for the intake air temperature sensor...
- ... and engine control unit for an open circuit and short circuit.

4-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
1 54
3 67

- If necessary, rectify open circuit or short circuit.

If no fault is detected in the wiring:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
- Fit a new intake air temperature permitted
sensorunless
(G42).
authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

1.5 - Checking output stages for ignition coils 103

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

1.7 - Checking the engine speed sensor

Notes:

◆ The engine speed sensor is a combined speed sensor and reference mark sensor.
◆ The engine cannot be started without a signal from the -G28 engine speed sensor.
◆ If the signal from the -G28 engine speed sensor fails while the engine is running, the engine will cut out
immediately.

Checking the engine speed sensor

Fitting location for the sensor and connector

=> Page 45 .

- Before carrying out the test, make sure that the sensor is correctly installed and firmly seated.
- Unplug the connector for the engine speed sensor (identification: grey connector).

- -> Connect the V.A.G 1526 hand held multimeter for resistance measurement to contacts 2 and 3 on the
connector.

Specified value: approx. 450...1000 ω.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
If the specified value is not permitted
achieved:unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
- Replace the engine speed sensor.

If the specified value is achieved:

- Connect the V.A.G. 1526 hand-held multimeter for resistance measurement between contacts 2 and 1
(earth) and to contacts 3 and 1 (earth).

Specified value: infinity in each case ω (no continuity).

104 28 - Ignition system

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

If the specified value is not achieved:

- Replace the engine speed sensor.

If the specified value is achieved:

- -> Check the wiring between the sensor connector and the engine control unit as follows:
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .

- -> Check the wiring from the 3 pin connector (sensor connector) ...
- ... to the engine control unit for an open circuit and short to positive or earth. Check the earth.

3-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
1 67
2 63
3 56

- If necessary, rectify open circuit or short circuit.

1.8 - Checking the sensor for coolant temperature

- Connect the V.A.G. 1551 fault reader => Page 2 .
- Select the function "Reading measured value block" (function 08) and Display Group 03.

-> Display readout:

Read measured value block 3
1 2 3 4

- Observe readout in display zone 3.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Specified
permitted value:
unless authorised TheAG.
by AUDI temperature
AUDI AG does not reading
guaranteeshould
or accept increase
any liability at a uniform rate.
with respect to the correctness of information in this document. Copyright by AUDI AG.
If display zone 3 shows an implausible value:

1.7 - Checking the engine speed sensor 105

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Switch the ignition off.

- -> Pull off the connector on the sensor => Overview of fitting locations, Page 45 .
- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- -> Check the wiring from the 4 pin connector ...
- ...t o the engine control unit for an open circuit and short to positive or earth. Check the earth.

4-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
1 67
3 53

- If necessary, rectify open circuit or short circuit.

If no fault is detected in the wiring:

- Replace the sensor for coolant temperature (G62).

1.9 - Checking the power supply for the control unit

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Test conditions

• Battery voltage OK.

- Connect the V.A.G. 1551 fault reader => Page 2 .

- Select the function "Reading measured value block" (function 08) and Display Group 03.

-> Display readout:

Read measured value block 3
1 2 3 4

- Check display in display zone 2.

Specified value: approx battery voltage

If the specified value is not achieved:

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- Connect the V.A.G 1526 hand held multimeter for voltage measurement to the following contacts on the test
box:

Contact Specified value

Ignition off 3 + 2 approx battery voltage
Ignition on 1 + 2 approx battery voltage

If the specified values are not achieved:

- Check the wiring.

=> Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder

1.10 - Checking the knock sensors

- Start the engine and run at idling speed.
- Connect the V.A.G. 1551 fault reader => Page 2 .

106 28 - Ignition system

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Select the function "Reading measured value block" (function 08) and Display Group 16.

-> Display readout:

Read measured value block 16
0.800 V 0.840 V 0.800 V
0.760 V

- Observe all display zones.

Specified value: 0.400...1.400 V.

- Compare the display zones with each other.

Specified value: Difference less than 0.500 V.

If the specified values are not achieved:

- Loosen knock sensors and tighten again

to 20 Nm. Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

- Repeat the test.

If the specified values are not achieved:

- Unplug the connector for the relevant knock sensor in the engine compartment.
- -> Test for a short circuit between all three contacts in the knock sensor connector. The must be no con‐
nection between any of the wires.
- If there is a connection between the contacts, replace the knock sensor.

Checking the wiring from the knock sensors to the engine control unit

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- -> Check the wiring from the relevant sensor connector ...

- ... to the engine control unit for an open circuit and short to positive or earth. Check the earth.

1.10 - Checking the knock sensors 107

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Knock sensor 1 -G61 (cylinders 1 and 2)

3-pin connector on the wir‐ Test box V.A.G 1598/22 or

ing harness contact engine control unit
1 (signal) 68
2 (earth) 67
3 (screening) 67

Knock sensor 2 -G66 (cylinders 3 and 4)

3-pin connector on the wir‐ Test box V.A.G 1598/22 or

ing harness contact engine control unit
1 (signal) 60
2 (earth) 67
3 (screening) 67

- If necessary, rectify open circuit or short circuit.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
1.11 - Checking the Hall sensor
with respect to the correctness of information in this document. Copyright by AUDI AG.

The Hall sensor indicates the ignition position for cylinder 1.

If the Hall sensor fails to function, the knock control is switched off and the ignition timing is retarded slightly
because the signals can no longer be assigned to the cylinders.

Even without a signal from the Hall sensor, the engine will continue to run and can also be re started.

◆ When a fault is detected, the engine control unit produces one spark for each cylinder on every crankshaft
revolution.
◆ The fact that the control unit is out of phase by one engine revolution does not have any noticeable effect
on the injection system. If this happens, the fuel is injected "upstream" (before the closed inlet valve) instead
of while the inlet valve is open. This has only a negligible influence on the quality of the air/fuel mixture.

Note on signal testing with an oscilloscope:

The centre point of the window of the Hall sensor must lie on the third trailing edge of the engine speed signal
after the reference mark gap.

- Push back the rubber sleeve on the Hall sensor connector.

- -> Connect the V.A.G 1527 diode test lamp to contacts 1 and 2 on the Hall sensor connector from behind
(the connector remains attached to the Hall sensor).

108 28 - Ignition system

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

Note:
The connector contacts are numbered on the back of the connector.
- Operate the starter for a few seconds.

The diode test lamp must flash briefly on each second engine revolution.
If the diode test lamp does not flash:
Check the power supply for the Hall sensor
- Unplug the connector from the Hall sensor.
- Switch on the ignition.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

- -> Connect the V.A.G 1526 hand held multimeter for voltage measurement contact 1 on the connector and
the engine earth.

Specified value: 4,5 ... 5.5 V.

Checking the signal wire for Hall sensor

- -> Connect the V.A.G 1526 hand held multimeter between contact 2 on the connector and the engine earth.

Specified value: approx battery voltage.

Checking the earth wire for the Hall sensor

- Connect the V.A.G 1526 hand held multimeter for resistance measurement between contact 3 on the con‐
nector and the engine earth.

Specified value: Continuity

If the specified values are all achieved and the diode test lamp does not flash (measured between contacts 1
and 2 with starter connector attached),
replace the Hall sensor.
If the specified values are not achieved:
Check the wiring between the Hall sensor and engine control unit

1.11 - Checking the Hall sensor 109

 Audi A3 1997 ➤
Motronic fuel injection and ignitionsystem (4-cyl. turbo) - Edition 11.1996

- Connect the V.A.G 1598/22 test box to the wiring harness for the engine control unit
=>Page 47 .
- -> Check the wiring from the Hall sensor ...
- ... to the engine control unit for an open circuit and short to positive or earth.

3-pin connector on the Test box V.A.G 1598/22

wiring harness contact contact
1 (positive) 62
2 (signal) 76
3 (earth) 67

- If necessary, rectify open circuit or short circuit.

- If a trial erasure of the fault memory is followed by the renewed indication of a fault relating to the camshaft
sensor (Hall sensor) although all previous tests were OK, the following faults are possible:
- Rotor ring for Hall sensor misaligned.
- Unbolt the Hall sensor, then check to ensure that the rotor ring is correctly aligned on the camshaft.(if it is
incorrectly installed, the catch will be pressed flat when the securing screw is tightened).
- If the position of rotor ring is OK, check the position of the camshaft in relation to the crankshaft.

=> 4- Cylinder Engine, Mechanics; Repair Group 15; Cylinder head, valve gear; Remove and install camshafts
and camshaft adjustment Cylinder head, valve gear Remove and install camshafts and camshaft adjustment

Note on signal testing with an oscilloscope:

The centre point of the window of the Hall sensor must lie on the third trailing edge of the engine speed signal
after the reference mark gap.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

110 28 - Ignition system