Service

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

Audi A4 2008 ➤
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.

Brake system
Edition 11.2007

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Service Department. Technical Information

 Service
List of Workshop Manual Repair GroupsList of Workshop Manual
Repair GroupsList of Workshop Manual Repair Groups

Repair Group
00 - Technical data
45 - Anti-lock brake system
46 - Brakes - mechanism
47 - Brakes - hydraulics

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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.

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 A005A400120

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Contents

00 - Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1 Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Brake test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 General notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Vehicles with front-wheel drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.3 Vehicles with four-wheel drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.4 EPB (Electronic parking brake and handbrake) on brake dynamometer . . . . . . . . . . . . . . 4
3 Brake fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 General notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

45 - Anti-lock brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

1 General information on the anti-lock brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Connecting VAS 5051B/ 5052 and selecting functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 ABS/ESP Bosch 8.1 - overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4 Audi hold assist (AHA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

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4.1 Removing and installing switch for Audi hold assist (AHA) . . . . . . . . . . . . . . . . . . . . . . . . 13
5 Removing and installing parts of ABS/ESP system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 Removing and installing brake light sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2 Removing and installing ESP sensor unit -G419- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.3 Removing and installing steering angle sender -G85- . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.4 Removing and installing switch for electronic parking brake . . . . . . . . . . . . . . . . . . . . . . . . 20
6 Hydraulic unit -N55- with ABS control unit -J104- - overview . . . . . . . . . . . . . . . . . . . . . . . . 21
6.1 Removing and installing hydraulic unit -N55- with ABS control unit -J104- . . . . . . . . . . . . 21
6.2 Removing and installing ESP bracket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7 Speed sensors of ABS/ESP system - overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
7.1 Removing and installing front speed sensors -G45- / -G47- . . . . . . . . . . . . . . . . . . . . . . . . 27
7.2 Removing and installing rear speed sensors -G44- / -G46- . . . . . . . . . . . . . . . . . . . . . . . . 28

46 - Brakes - mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1 Front brakes FN3-57 - exploded view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1.1 Removing and installing front brake caliper with brake carrier - FN-3 brakes . . . . . . . . . . 31
1.2 Renewing front brake caliper - FN-3 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
1.3 Removing and installing front brake pads - FN-3 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . 37
1.4 Removing and installing front brake disc - FN-3 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
1.5 Renewing front brake disc - FN-3 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1.6 Removing and installing front splash plate - FN-3 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2 Front brakes FBC-57 - exploded view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2.1 Removing and installing front brake caliper with brake carrier - FBC-57 brakes . . . . . . . . 47
2.2 Renewing front brake caliper - FBC-57 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
2.3 Removing and installing front brake pads - FBC-57 brakes . . . . . . . . . . . . . . . . . . . . . . . . 52
2.4 Removing and installing front brake disc - FBC-57 brakes . . . . . . . . . . . . . . . . . . . . . . . . 60
2.5 Renewing front brake disc - FBC-57 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.6 Removing and installing front splash plate - FBC-57 brakes . . . . . . . . . . . . . . . . . . . . . . . .
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
65
3 Rear brakes with electronic parking
withbrake
respect to- the
exploded
correctnessview . . . in. this
of information . . document.
. . . . . .Copyright
. . . . .by. AUDI
. . . AG.
... 66
3.1 Removing and installing rear brake caliper with brake carrier . . . . . . . . . . . . . . . . . . . . . . 67
3.2 Renewing rear brake caliper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.3 Removing and installing rear brake pads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.4 Detaching and attaching rear brake disc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.5 Renewing rear brake disc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
3.6 Removing and installing rear splash plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4 Brake pedal and mounting bracket - exploded view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Contents i
 Audi A4 2008 ➤
Brake system - Edition 11.2007

4.1 Separating and connecting brake pedal and brake servo . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.2 Removing and installing brake pedal (vehicles with manual gearbox) . . . . . . . . . . . . . . . . 92
4.3 Removing and installing brake pedal (vehicles with automatic gearbox) . . . . . . . . . . . . . . 95
4.4 Removing and installing mounting for brake servo push rod . . . . . . . . . . . . . . . . . . . . . . . . 100
4.5 Removing and installing mounting bracket (vehicles with manual gearbox) . . . . . . . . . . . . 104
4.6 Removing and installing mounting bracket (vehicles with automatic gearbox) . . . . . . . . . . 116
5 Electronic parking brake (EPB) - overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
5.1 Removing and installing control unit for electromechanical parking brake -J540- . . . . . . . . 126
5.2 Removing and installing actuator motor for electronic parking brake and handbrake . . . . 127

47 - Brakes - hydraulics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

1 Leak test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
1.1 Leak test performed by operating brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
1.2 High-pressure and low-pressure tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
2 Servicing brake caliper - FN3 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
2.1 Removing and installing piston for front brake caliper - FN-3 brakes . . . . . . . . . . . . . . . . . . 135
2.2 Renewing bearing bushes and guide pins - FN-3 brakes . . . . . . . . . . . . . . . . . . . . . . . . . . 136
3 Servicing brake caliper - FBC brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
3.1 Removing and installing piston for front brake caliper- FBC brakes . . . . . . . . . . . . . . . . . . 139

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3.2 Renewing protective caps and guide pins - FBC brakes . . . . . . . . . . . . . . . . . . . . . . . . . . 140
4 Servicing rear caliper for electronic parking brake (EPB) . . . . . . . . . . . . . . . . . . . . . . . . . . 145
4.1 Removing and installing piston for rear brake caliper . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
4.2 Renewing protective caps and guide pinsby of
Protected rear Copying
copyright. brakesfor private
. . . .or.commercial
. . . . . . purposes,
. . . . . in. .part
. .or. in. whole,
. . . .is 149
not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
5 Bleeding brake system . . . . . . . . .with . . respect
. . . . to. .the. correctness
. . . . . . .of. information
. . . . . . in. this
. . document.
. . . . . . Copyright
. . . . . by . .AUDI
. . .AG.
. 151
5.1 Procedure for bleeding brake system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
5.2 Changing brake fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
6 Brake servo/ brake master cylinder - exploded view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
6.1 Removing and installing cover for brake fluid reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
6.2 Removing and installing brake fluid reservoir . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
6.3 Removing and installing brake master cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
6.4 Removing and installing brake servo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
7 Exhauster pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
7.1 Exhauster pump - exploded view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
7.2 Removing and installing exhauster pump (2.7 ltr. TDI and 3.0 ltr. TDI diesel engine) . . . . 168
7.3 Removing and installing exhauster pump (2.0 ltr. TDI diesel engine) . . . . . . . . . . . . . . . . 170
7.4 Removing and installing exhauster pump (4-cyl. turbo FSI engine) . . . . . . . . . . . . . . . . . . 172
7.5 Removing and installing exhauster pump (V6 FSI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
8 Vacuum pump -V192- - overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
8.1 Removing and installing vacuum pump -V192- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
8.2 Removing and installing bracket for vacuum pump -V192- . . . . . . . . . . . . . . . . . . . . . . . . 176
8.3 Checking vacuum pump -V192- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177
8.4 Removing and installing brake servo pressure sensor G294 . . . . . . . . . . . . . . . . . . . . . . 180
8.5 Removing and installing non-return valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
8.6 Checking non-return valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
9 Brake hoses and brake lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
9.1 Routing of brake hoses/lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182

ii Contents
 Audi A4 2008 ➤
Brake system - Edition 11.2007

00 – Technical data
1 Brakes
The PR numbers are listed in the following tables. They indicate
the required combination of brake calipers, discs and brake pads.
Brake system
Diagonally split dual-circuit braking system with ABS, EBPD, EDL, ASR, ESP, ECD and vacuum pump

Front brakes
Manufacturer coding (PR No.) 1LT 1LA 1LJ
Brake caliper FN3- 57 16” FBC-57 16” FBC-57 17”
Ventilated brake disc ∅ mm 314 320 345
Brake disc, thickness mm 25 30 30
Brake disc, wear limit mm 23 28 28

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Brake caliper, piston ∅ mm 57 57 57
Brake pad thickness (including back‐ mm 20.3 18.8 18.8
plate and damper plate)
Brake pad wear limit (including back‐ mm 7 7 7
plate and damper plate)

Rear brakes
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Manufacturer coding (PR
permitted unless authorised by AUDI AG. AUDI 1KW AG does not guarantee or accept any liability 1KE
No.) with respect to the correctness of information in this document. Copyright by AUDI AG.

Brake caliper CII-43 EPB (16”) CII-43 EPB (17”)

Brake disc ∅ mm 300 330
Brake disc (not ventilated), mm 12 ------
thickness
Brake disc (ventilated), ------ 22
thickness
Brake disc, wear limit mm 10 20
Brake caliper, piston ∅ mm 43 43
Brake pad thickness (in‐ mm 17.5 17.5
cluding backplate and
damper plate)
Brake pad wear limit (in‐ mm 7 7
cluding backplate and
damper plate)

1. Brakes 1
 Audi A4 2008 ➤
Brake system - Edition 11.2007

The type of brake system installed in the vehicle is indicated by

the corresponding PR number -A and B- on the vehicle data stick‐
er.
♦ Allocation ⇒ ETKA

Note

♦ When performing repair work on brakes, hairline cracks are

often found on the friction surface of the brake discs. Hairline
cracks up to a length of 10 mm do not present a technical
problem and do not justify a renewal of brake discs.
♦ Brake discs and pads with cracks going all the way across the
friction surface must be renewed.

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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.

2 Rep. Gr.00 - Technical data

 Audi A4 2008 ➤
Brake system - Edition 11.2007

2 Brake test

2.1 General notes

The wheels are driven by the brake test rollers.
During the test the gearbox must be in neutral on manual gear‐
boxes or in position N on automatic gearboxes.
Follow the instructions provided by the manufacturer of the brake
test equipment when performing the test.
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
Note with respect to the correctness of information in this document. Copyright by AUDI AG.

Electronic brake control systems are inoperative when the ignition

is switched off.

Please note the following if test and measuring equipment has to

be used during a test drive:

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WARNING

There is a risk of accident if the driver's attention is distracted

or if the test and measuring equipment is not adequately se‐
cured during the test drive.
There is a risk of injury if the passenger's airbag is triggered
during an accident.
• The operation of test and measuring equipment during a
test drive distracts the driver's attention.
• There is an increased risk of injury if test and measuring
equipment is not secured.
♦ Move the passenger's seat back as far as possible.
♦ Use only vehicle diagnosis, testing and information sys‐
tem -VAS 5051- or vehicle diagnosis and service informa‐
tion system -VAS 5052- or diagnosis system -VAS 5053- .
♦ The test and measuring equipment -1- must rest horizon‐
tally on the passenger's thighs as illustrated and must be
operated by the passenger.

2.2 Vehicles with front-wheel drive

Perform brake test on a single-axle brake dynamometer.
Test speed must not exceed 6 km/h. Otherwise the EDL control
can activate the brakes if the rollers start at different points in time.
All brake test equipment approved by Audi meets these require‐
ments.

2.3 Vehicles with four-wheel drive

Testing on a single-axle brake dynamometer for four-wheel drive
vehicles:
The rollers drive the wheels of one axle in opposite directions to
avoid transmitting torque to the other axle.
Test speed must not exceed 6 km/h. Otherwise the EDL control
can activate the brakes if the rollers start at different points in time.

2. Brake test 3
 Audi A4 2008 ➤
Brake system - Edition 11.2007

WARNING

The Torsen differential will be seriously damaged if test speed

exceeds 6 km/h.

All brake test equipment approved by Audi meets these require‐

ments.

2.4 EPB (Electronic parking brake and

handbrake) on brake dynamometer
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Test sequence: 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.
– Drive rear wheels of vehicle onto test rollers; do not switch off
ignition.
– The “test mode” (TÜV mode) is activated as soon as the rollers
reach a speed between 3 km/h and 9 km/h.
The instrument cluster display will show “Parking brake under di‐
agnosis” when the test mode is activated.

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The EPB will now function as follows:
The full brake force is not applied at once, but step by step each
time the parking brake switch is pulled.
After operating the switch a few times the brake force attained is
sufficient for the measuring procedure.
The brake is released by pressing the switch once.
Requirements for “test mode”:
– Ignition on
– Front wheels, speed = 0 km/ h
– Rear wheels, min. speed = 3 km/ h, max. speed = 9 km/h
The instrument cluster display will show “Parking brake under di‐
agnosis” when the test mode is activated.

WARNING

When testing models with four-wheel drive you must use brake
test rollers with synchronised wheel speeds.

4 Rep. Gr.00 - Technical data

 Audi A4 2008 ➤
Brake system - Edition 11.2007

3 Brake fluid

3.1 General notes

Brake fluid is hygroscopic, i.e. it has the tendency to absorb water
and moisture from the atmosphere.
The boiling point decreases as the water content increases, which
means a considerable rise in brake fluid temperature can lead to
formation of vapour bubbles and brake failure.
The colour of the brake fluid becomes darker over the course of
time. A dark brake fluid colour is not an indication of its condition.
The change in colour is caused by chemical reactions.

WARNING

Rubber parts of brake system (sleeves, seals)

Protected are not
by copyright. com‐
Copying for private or commercial purposes, in part or in whole, is not
patible with mineral oil, fuel and cleaning agents.
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.

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Even minute quantities coming into contact with a seal or sleeve
will affect the component and could impair brake operation. The
consequences of a contaminated brake system only become ap‐
parent months later, and then give rise to greater expenses,
particularly in vehicles equipped with ABS.

A = Sleeve (original size)

B = Sleeve (swollen due to contact with mineral oil)
Summary of the above mentioned points:
Always keep brake fluid containers properly sealed. This is the
only way of preventing contamination by oil, dirt, cleaning agents
or moisture.
Brake fluid containers should be kept completely separate from
oils (including hydraulic fluid) and cleaning agents to prevent any
mixture of fluids or even filling of the brake system with an incor‐
rect fluid.
We recommend using brake fluid approved by Audi ⇒ ETKA .

3. Brake fluid 5
 Audi A4 2008 ➤
Brake system - Edition 11.2007

45 – Anti-lock brake system

1 General information on the anti-lock
brake system

WARNING

The anti-lock brake system is basically maintenance-free.

Testing, removing, installing and repair work may only be per‐
formed by qualified personnel.
Failure to observe the information described in this Workshop
Manual may result in damage to the system and could make
the vehicle unsafe.

♦ Before carrying out repair work on the anti-lock brake system,

determine the cause of the problem using self-diagnosis.

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♦ If a new hydraulic control unit has been fitted, you must check
that it has the correct coding. Use vehicle diagnosis and serv‐
ice information system -VAS 5051 B- or -VAS 5052- .
♦ Always switch off the ignition before carrying out installation
or repair work. On vehicles with a coded radio, find out the anti-
theft code and disconnect the battery earth strap.
♦ When working with brake fluid, observe the relevant safety
precautions and notes ⇒ page 5 .
♦ Always bleed the brake system (using brake filling and bleed‐
ing equipment -VAS 5234- ) after all work which involves
opening the hydraulic system. In addition, a high- and low-
pressure test should be carried out on the brake system
⇒ page 132
♦ During the final road test, ensure that at least one ABS-con‐
trolled braking operation is performed (pulsation must be felt
at the brake pedal). See vehicle diagnosis and service infor‐
mation system -VAS 5051 B- or -VAS 5052- .
♦ Absolute cleanliness is required when working on the anti-lock
brake system; avoid any products that contain mineral oil,
such as oil, grease, etc.
♦ Thoroughly clean all connections and the adjacent areas be‐
fore loosening; do not use harsh cleaning agents such as
brake cleaner, fuel, thinners or similar.
♦ Place removed parts on a clean surface and cover them up.
♦ Carefully cover or seal open components if repairs are not to
be carried out immediately. (Use sealing plugs from repair kit
1 H0 698 311 A).
♦ Only use lint-free cloths.
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♦ Only remove replacement parts from packaging immediately
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
prior to installation. with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Only use genuine spare parts from original packaging.

♦ When the system is open do not work with compressed air and
do not move the vehicle.
♦ Ensure that no brake fluid enters electrical connectors.

6 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

2 Connecting -VAS 5051B/ 5052- and

selecting functions
Special tools and workshop equipment required
♦ Vehicle diagnosis and service information system -VAS 5051
B- or -VAS 5052-

– Plug in connector of diagnosis cable at diagnostic connection.

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– Switch on tester.
– Switch on ignition.
– Press the Guided Fault Finding button on the display screen.
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
– Select the following:
with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Make
♦ Model
♦ Model year
♦ Version
♦ Engine code letters
– Confirm the entered information.
Wait until the tester has interrogated all the control units in the
vehicle.
– Press the Go to button and select the option “Function/com‐
ponent selection”.
– Select “Running gear” on the display.
– Select “Brake system” on the display.
– Select “01 - Self-diagnosis compatible systems ...” on the dis‐
play.
– Select “Anti-lock brake system ...” on the display.
– Select “Function” on the display.
You will now see displayed all possible functions for the anti-lock
brake system installed in the vehicle.
– Select the function you require on the display.

2. Connecting VAS 5051B/ 5052 and selecting functions 7

 Audi A4 2008 ➤
Brake system - Edition 11.2007

3 ABS/ESP Bosch 8.1 - overview

The Bosch ESP 8.1 system includes the following features:
♦ ABS - anti-lock brake system
♦ ASR - traction control system (TCS)
♦ EBPD - electronic brake pressure distribution
♦ EDL - electronic differential lock
♦ ESP - electronic stabilisation program
♦ FBS - fading brake support
♦ HBA - hydraulic brake assist system
♦ EBC - Engine braking control
♦ Emergency braking signal
♦ Pad wipe function
♦ Trailer stabilisation
The brake system is split diagonally. The servo-assistance is

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pneumatic, supplied by the vacuum brake servo unit.
Malfunctions in the ABS system do not influence the brake system
and servo. The conventional braking system remains functional
even without ABS. A change in braking behaviour must be reck‐
oned with. After the ABS warning lamp comes on, the rear wheels
can lock early when braking.
The direct connection between these components reduces pos‐
sible sources of faults. There is no provision for repairing the
components - they must be renewed if necessary.

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 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

1 - Rear right speed sensor -

G44-
❑ Removing and installing
⇒ page 28
❑ Can be checked in “Gui‐
ded Fault Finding” using
vehicle diagnosis and
service information sys‐
tem -VAS 5051B- or -
VAS 5052-
2 - Rear left speed sensor -
G46-
❑ Removing and installing
⇒ page 28
3 - ESP sensor unit --G419--
❑ Fitting location: under
seat (left-side)
❑ Removing and installing
⇒ page 18
❑ 9 Nm

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❑ Combined lateral accel‐
eration sender -G200-,
yaw rate sender -G202-
and longitudinal accel‐
eration sender -G251-
❑ Can be checked in “Gui‐
ded Fault Finding” using
vehicle diagnosis and
service information sys‐
tem -VAS 5051B- or -
VAS 5052-
❑ Observe installation in‐
structions
❑ When installing ensure
that arrow points in di‐
rection of travel
4 - Brake light sensor
❑ Fitting location: on brake pedal
❑ Removing and installing ⇒ page 14
❑ Can be checked in “Guided Fault Finding” using vehicle diagnosis and service information system -VAS
5051B- or -VAS 5052-
Can be re-installed if removed

5 - Brake pedal
❑ With bracket for brake light sensor
❑ Removing and installing; vehicles with manual gearbox ⇒ page 92
❑Protected
Removing and installing; vehicles with automatic gearbox ⇒ page 95
by copyright. Copying for private or commercial purposes, in part or in whole, is not

6 - Warning lampto thefor electronic parkingin thisbrake

permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect correctness of information document. Copyright by AUDI AG.
❑ Fitting location: in speedometer
❑ Lights up when parking brake is engaged and ignition is switched on,
❑ Lights up for 20 seconds when parking brake is engaged and ignition is switched off,
❑ Flashes when parking brake has been engaged if available braking force is not sufficient to prevent
vehicle from rolling away
7 - Brake system warning lamp -K118-
❑ Fitting location: in speedometer
❑ Lights up together with ABS warning lamp if ABS should fail

3. ABS/ESP Bosch 8.1 - overview 9

 Audi A4 2008 ➤
Brake system - Edition 11.2007

❑ Flashes if brake fluid level is too low

❑ Flashes if there is a malfunction in the brake system
Press “SET button” to display driver message with further information in instrument cluster

8 - Warning lamp for anti-lock brake system (ABS) -K47-

The warning lamp monitors the ABS and the electronic differential lock (EDL)
❑ Fitting location: in speedometer
❑ Lights up for a few seconds when the ignition is switched on and goes out after the automatic ABS self-
test has been completed, providing no faults have been detected in the ABS.
❑ There is a malfunction of the ABS if the warning lamp:
♦ does not light up when the ignition is switched on,
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ does not go out again after a few seconds,
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.
♦ lights up while the vehicle is in motion.
❑ Malfunctions in the ABS system do not influence the brake system itself. However, a change in braking
behaviour must be reckoned with.
The electronic differential lock (EDL) operates in conjunction with the ABS. The ABS warning lamp will light up
if a fault occurs in the EDL.

9 - ESP/ASR warning lamp (for electronic stabilisation program and traction control system) -K155-

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❑ Fitting location: in rev counter
❑ Flashes when the vehicle is in motion and the ESP/TCS control is in operation
❑ Lights up when the ignition is switched on and goes out after a short self-test has been completed
❑ Lights up if there is a malfunction in the ESP
❑ Lights up if there is a malfunction in the ABS, since the ESP works in conjunction with the ABS
❑ Lights up when the traction control system (ASR) is switched off
❑ Lights up during automatic self-adaption of the sensor systems when:
♦ the battery has been disconnected and then re-connected
♦ the vehicle has been jump-started
♦ the battery charge level is very low
❑ The ESP warning lamp goes out after the vehicle has been in motion for a short time as soon as the
automatic self-adaption procedure of the sensor systems is finalised
10 - Front left speed sensor -G47-
❑ Removing and installing ⇒ page 27
❑ Can be checked in “Guided Fault Finding” using vehicle diagnosis and service information system -VAS
5051B- or -VAS 5052-
11 - Hydraulic unit -N55- with control unit -J104-
❑ Removing and installing ⇒ page 21
12 - Return ring
❑ Removing and installing ⇒ page 19
13 - Steering angle sender --G85--
❑ Fitting location: incorporated in return ring with slip ring on steering column ⇒ Body Repairs; Rep. Gr.
69
❑ Removing and installing ⇒ page 19
❑ Performing zero compensation
Vehicle diagnosis and service information system -VAS 5051B- or -VAS 5052-

14 - Front right speed sensor -G45-

❑ Removing and installing ⇒ page 27
15 - TCS (ASR)/ESP button -E256-
❑ Fitting location: in centre console
❑ Switches traction control system (ASR) off and on

10 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

16 - Switch for Audi hold assist

❑ Fitting location: in centre console
❑ Function ⇒ page 12
❑ Removing and installing ⇒ page 13
17 - Switch for electronic parking brake -F234-
❑ Fitting location: in centre console
❑ Removing and installing ⇒ page 20
18 - Diagnostic socket
❑ Fitting location: cover in driver's footwell

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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. ABS/ESP Bosch 8.1 - overview 11

 Audi A4 2008 ➤
Brake system - Edition 11.2007

4 Audi hold assist (AHA)

Some models are equipped with the Audi hold assist feature
(AHA).
Function
This function assists the driver when the vehicle has to be held
stationary, either frequently or for long periods, with the engine
running.
When the Audi hold assist is activated after the vehicle comes to
a standstill, it will hold the vehicle in a stationary position.
The driver can then release the brake pedal.
Initially the vehicle is held at a standstill by maintaining the brake
pressure at all four wheels in the
AG. ESP system.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AUDI AG does not guarantee or accept any liability

To prevent the ESP solenoid valves from overheating if the vehi‐

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

cle has to be held for long periods, the braking function is taken
over automatically by the rear electronic parking brake if the tem‐
perature at the solenoid valves exceeds 200 °C.
The brakes are released automatically at a point determined ac‐

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cording to the following factors:
♦ Engine torque
♦ Angle of gradient
♦ Gear engaged
♦ Manual gearbox: clutch pedal travel (as detected by clutch
sensor)
♦ Automatic gearbox: torque converter slip
To prevent the vehicle from rolling back, the brakes are only re‐
leased when sufficient engine torque is available.
Activation
The following requirements must be met in order to switch on the
“stand-by” mode:
♦ Driver's seat belt fastened
♦ Engine running
♦ Driver's door closed
♦ No faults in ESP or electronic parking brake.

12 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

The function can then be activated by pressing the switch -2- in

the centre console.
The switch indicates the status of the system:
♦ Deactivated: LED in switch remains off.
♦ Stand-by: LED in switch lights up
♦ Active: LED in switch lights up and a green “P” appears in the
instrument cluster display
The electronic parking brake only takes over the braking function
from the ESP when the green “P” appears in the instrument clus‐
ter display and when:
♦ The ESP solenoid valves reach a temperature of 200 °C,
♦ The driver's door is opened,
♦ The driver's seat belt is unfastened,
♦ The engine is switched off,
♦ The ignition is switched off,
♦ The switch is operated,

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♦ The brake pedal or accelerator pedal is operated,
♦ The switch for the Audi hold assist function is operated without
pressing the footbrake.

Note

The green “P” in the instrument cluster display changes to a red

“P” when the electronic parking brake takes over the braking
function from the ESP.

4.1 Removing and installing switch for Audi

hold assist (AHA)
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Removing 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 centre console ⇒ Rep. Gr. 68 .
– Remove switch for Audi hold assist (AHA) -2- ⇒ Rep. Gr. 96 .
Installing
– Installation is carried out in reverse sequence.

4. Audi hold assist (AHA) 13

 Audi A4 2008 ➤
Brake system - Edition 11.2007

5 Removing and installing parts of

ABS/ESP system

5.1 Removing and installing brake light sen‐

sor

Note

♦ The brake light sensor can be re-used after it has been re‐
moved.
♦ The brake light sensor is self-adapting. Calibration is not re‐
quired after installing the sensor.

Removing
– Remove driver's storage compartment -1 ... 3-.

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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.

– Unplug electrical connector on footwell vent -C-.

– Remove footwell vent -A-B-.
– Unplug connector on brake light sensor.

14 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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Note

Stop -17- on brake pedal must always be fitted, otherwise there

is a risk that mounting for brake light sensor -10- can break off
when brake pedal is released.

– Press plunger of brake light sensor -10- fully in with one finger.
– With plunger still pressed in, turn coloured catch on brake light
sensor fully anti-clockwise to release sensor.

Note

Keep the plunger pressed in while releasing the brake light sen‐
sor.
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
– Let go of plunger after releasing brake light sensor.
with respect to the correctness of information in this document. Copyright by AUDI AG.

– Insert release tool -T40168- between brake pedal and plunger

of brake light sensor.

5. Removing and installing parts of ABS/ESP system 15

 Audi A4 2008 ➤
Brake system - Edition 11.2007

The tapered part of the special tool must face towards the driver's
seat. The slot on the special tool must correspond with the recess
on the brake light sensor.
– Press release tool -T40168- against brake light sensor. This
releases the three retaining tabs on the brake light sensor.
– Pull brake light sensor out of its mounting.
Installing

Note

Stop -17- on brake pedal must always be fitted, otherwise there

is a risk that mounting for brake light sensor -10- can break off
when brake pedal is released.

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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.

16 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

♦ The plunger adjusts itself automatically when the brake light

sensor is inserted.
♦ The brake pedal must remain in the normal position during
installation and must not be depressed.
♦ The brake pedal must be connected to the brake servo.

– Fit brake light sensor in mounting on brake pedal and press in

lightly.

Note

♦ All three retaining tabs on the brake light sensor must engage
audibly.
♦ The switch must not be rotated in the mounting on the brakeby 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
permitted unless authorised
pedal. with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ The plunger adjusts itself automatically when the brake light

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sensor is inserted.

– Turn coloured catch on brake light sensor fully clockwise to

secure sensor.
– Plug in electrical connection for brake light sensor.
– Install footwell vent -A-B-.
– Tighten bolt securing footwell vent -A-.

– Attach electrical connector to footwell vent -C-.

– Install driver's storage compartment -1 ... 3-.
After installing the brake light sensor, check the function of the
sensor before driving the vehicle.

5. Removing and installing parts of ABS/ESP system 17

 Audi A4 2008 ➤
Brake system - Edition 11.2007

5.2 Removing and installing ESP sensor

unit -G419-

WARNING

The ESP sensor unit is sensitive to impact. Severe shocks or

jolts can damage the ESP sensor unit. If the ESP sensor unit
has been dropped by mistake it may not work properly and
must not be installed in the vehicle.

The ESP sensor unit -G419- is located under the left-side seat on
all vehicles.
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1410-

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Removing
The ESP sensor unit -G419- is located under the left-side seat.
The arrow on the ESP sensor unit -G419- points in the direction
of travel.
– Remove seat (left-side) ⇒ Rep. Gr. 72 .
– Fold up seam on carpet.
Use a sharp knife to cut through the carpet seam if this has not
already been done.
– Detach footwell vent.
– Unplug electrical connector -2-.
– Remove securing nuts on sensor unit.
– Lift out ESP sensor unit -G419- -1-.
Installing

Note

The arrow on the sensor unit points in the direction of travel.

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

Severe shocks or jolts can irreparably damage the ESP sensor

unit -G419- .

18 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Fit ESP sensor unit -G419- -1- into mountings from above.
When installing the ESP sensor unit -G419- , make sure it is cor‐
rectly seated in its bracket and is free of stress.
– Install and tighten securing nuts on sensor unit.

– Plug in electrical connector -2-.

– Install footwell vent.
– Fold down seam on carpet.
– Install seat (left-side) ⇒ Rep. Gr. 72 .
After renewing ESP sensor unit -G419-, the following senders
must be calibrated (basic setting):

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♦ Lateral acceleration sender -G200-
♦ Longitudinal acceleration sender -G251-
Use vehicle diagnosis and service information system -VAS
5051B- or -VAS 5052- to do this.
– Select on the display:
♦ Running gear
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Brake system 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.
♦ 01 - Self-diagnosis compatible systems
♦ 03 - Brake electronics
– Select required function on the display:
♦ Calibrate lateral acceleration sender -G200-
♦ Calibrate longitudinal acceleration sender -G251-
– Then carry out ESP road test and system test.

5.3 Removing and installing steering angle

sender -G85-
The steering angle sender -G85- is located between the steering
wheel and the steering column switch.
Removing
– Turn wheels to straight ahead position.

5. Removing and installing parts of ABS/ESP system 19

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Return ring with slip ring -1-

– Remove airbag unit and steering wheel ⇒ Rep. Gr. 48 .
- Clipped onto switch for turn signals, main/dipped beam head‐
lights and headlight flasher.
- Clipped onto return ring with slip ring.

WARNING

The return ring with slip ring must not be rotated following re‐
moval.

– Remove steering column switch module ⇒ Rep. Gr. 94 .

Installing
Installation is carried out in the reverse sequence.
– Install airbag unit and steering wheel ⇒ Rep. Gr. 48 .
– Calibrate steering angle sender -G85-.

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Use vehicle diagnosis and service information system -VAS
5051B- or -VAS 5052- .

– Select on the display:

♦ Running gear
♦ Brake system (Repair group 01; 45)
♦ 01 - Self-diagnosis compatible systems
♦ 03 - Brake electronics ABS/ESP
– Select the function you require on the display.
♦ -J104 - Control unit for ABS/ASR/ESP, Functions
♦ -G85- Calibration of steering angle sender ⇒ Vehicle diagno‐
sis and service information system -VAS 5051 B- or -VAS
5052-
– Then carry out ESP road test and system test.

5.4 Removing and installing switch for elec‐

tronic parking brake
Removing
– Remove centre console (MMI) ⇒ Rep. Gr. 68 .
– Remove parking brake contact switch -F321- -1- ⇒ Rep. Gr.
96 .
The switch is clipped into the frontProtected
of the bycentre console on one
copyright. Copying for private or commercial purposes, in part or in whole, is not
side. 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.
Installing
– Installation is carried out in the reverse sequence.

20 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

6 Hydraulic unit -N55- with ABS control unit -J104- - overview

1 - ABS hydraulic unit -N55-

with ABS control unit -J104-
❑ Fitting location: In en‐
gine compartment (front
left)
❑ Removing and installing
⇒ page 21
❑ Hydraulic unit -N55-
with integrated brake
pressure sender -G201-
and ABS control unit -
J104- together form the
hydraulic control unit
❑ These components
must not be separated
❑ Do not unplug connec‐
tor before completing
self-diagnosis

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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 off ignition be‐ with respect to the correctness of information in this document. Copyright by AUDI AG.
fore detaching connec‐
tor
❑ Brake pressure sender -
G201- is integrated in
hydraulic unit -N55- and
cannot be renewed sep‐
arately

Caution
ABS hydraulic unit -N55-
and ABS control unit -
J104- must not be sepa‐
rated.

2 - Bracket for ESP

❑ The bracket cannot be removed
3 - Electrical connector for control unit -J104-
4 - Brake line
❑ To brake master cylinder
5 - Brake line
❑ To brake master cylinder
6 - Brake lines
❑ Hydraulic unit to front right brake caliper
❑ Hydraulic unit to front left brake caliper
❑ Hydraulic unit to rear left brake caliper
❑ Hydraulic unit to rear right brake caliper

6.1 Removing and installing hydraulic unit -

N55- with ABS control unit -J104-
Hydraulic unit -N55- with ABS control unit -J104- is located in the
engine compartment (front left).
Special tools and workshop equipment required

6. Hydraulic unit -N55- with ABS control unit -J104- - overview 21

 Audi A4 2008 ➤
Brake system - Edition 11.2007

♦ Brake pedal actuator -V.A.G 1869/2-

♦ Sealing plugs (repair kit) -1H0 698 311 A-

Caution

ABS control unit -J104- and ABS hydraulic unit -N55- must not
be separated.

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Removing
– Read out control unit version and note down.
Use vehicle diagnosis and service information system -VAS
5051B- or -VAS 5052- .
– Disconnect battery ⇒ Rep. Gr. 27 (note radio code).
– Insert brake pedal actuator -V.A.G 1869/2- between brake
pedal and driver's seat (depress brake pedal at least 60 mm).
This closes the valves in the brake master cylinder and stops
the brake fluid reservoir from running dry.
– Connect hose of bleeder bottle to bleeder screw of front left
brake caliper.
– Connect hose of bleeder bottle to bleeder screw of rear left
brake caliper.
– Open bleeder screws of front left and rear left brake calipers
to release pressure in hydraulic unit -N55-.
– Close bleeder screws (front left and rear left).

Note

Do not remove brake pedal actuator -V.A.G 1869/2- .

– Push retainer catch on electrical connector -1- for control unit

upwards.
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.

22 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Pull retainer clip in -direction of arrow- and unplug connector.

Note

♦ Make sure brake fluid does not get into connector housing of
control unit. This can result in corrosion of the contacts and
failure of the system.
♦ Use compressed air to carefully clean connector housing if
necessary.

– To protect against escaping brake fluid, place a sufficient

number of lint-free cloths in area beneath control unit -J104-
and hydraulic unit -N55-.
– Mark brake lines for subsequent installation.

WARNING

Do not bend or kink brake lines.

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– Disconnect brake lines between hydraulic unit -N55- and
brake master cylinder.

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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. Hydraulic unit -N55- with ABS control unit -J104- - overview 23

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Disconnect remaining brake lines -arrows- from hydraulic unit

-N55-.
– Seal brake lines and threaded holes using sealing plugs from
repair kit.
– Carefully lift hydraulic unit -N55- together with ABS control unit
-J104- out of mounting bracket.
Make sure that the rubber buffers do not drop into the engine
compartment when detaching the ESP control assembly from the
mounting bracket.

WARNING

Severe shocks or jolts can damage the control unit. The control
unit must not be re-installed if it has been damaged in any way.

– Place hydraulic unit -N55- on a clean flat surface with control

unit -J104- facing downwards.
Seal threaded holes and brake lines using sealing plugs after re‐
moving ABS control unit -J104- and hydraulic unit -N55-.

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WARNING

Hydraulic pump must not be separated from hydraulic unit -

N55-.

Installing
Installation is performed in reverse sequence; note the following:

Note

♦ The hydraulic unit -N55- supplied as a replacement is filled

with brake fluid.
♦ Do not remove sealing plugs from new hydraulic unit -N55-
until corresponding brake line is ready to be fitted.
♦ If sealing plugs are removed from hydraulic unit -N55- before
fitting corresponding brake line, brake fluid will escape. Proper
bleeding is then no longer ensured.
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
All rubber buffers
with must
respect be
to thefitted in the
correctness mounting
of information in thisbracket.
document. Copyright by AUDI AG.

– Press hydraulic unit -N55- with control unit -J104- facing down‐
wards into mounting bracket in vehicle.
Hold the rubber buffers in place when pressing in the ESP control
assembly to prevent them from dropping out.
– Connect brake lines as previously marked.

WARNING

Interchanging brake line connections will result in ABS/ESP

system malfunction.

24 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

Final control diagnosis can be used to establish whether line con‐

nections have been interchanged.

– Connect all brake lines -arrows- to hydraulic unit -N55-.

Component Nm
Brake lines to hydraulic unit M10 (brake line di‐ 12
ameter 5 mm)
Brake lines to hydraulic unit M12 (brake line di‐ 12
ameter 5 mm)
Brake lines to hydraulic unit M12 (brake line di‐ 16
ameter 8 mm)
– Attach electrical connector to control unit -J104-.
– Press down retaining clip so that it engages audibly.

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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. Hydraulic unit -N55- with ABS control unit -J104- - overview 25

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Press down retainer catch -1- so it engages.

– Remove brake pedal actuator -V.A.G 1869/2- .
– Bleed brake system ⇒ page 151 .
– Perform final control diagnosis after securing brake lines to
hydraulic unit -N55-.

Note

Final control diagnosis can be used to establish whether line con‐

nections have been interchanged.
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Use vehicle diagnosis and service information permitted
systemunless
-VAS authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
5051B- or -VAS 5052- to do this. with respect to the correctness of information in this document. Copyright by AUDI AG.

If a new ABS control unit -J104- has been fitted, it must be enco‐
ded.
Use vehicle diagnosis and service information system -VAS
5051B- or -VAS 5052- .
– Select on the display:

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♦ Running gear
♦ Brake system
♦ 01 - Self-diagnosis compatible systems
♦ 03 - Brake electronics.
– Select required function on the display:
♦ J104 Control unit for ABS/ASR/ESP
♦ J104 Control unit for ABS/ASR/ESP, functions
♦ J104 Code control unit
Also calibrate the following senders after renewing control unit
J104.
♦ Steering angle sender -G85-
♦ Lateral acceleration sender -G200-
♦ Longitudinal acceleration sender -G251-
Use vehicle diagnosis and service information system -VAS
5051B- or -VAS 5052- .
– Select on the display:
♦ Running gear
♦ Brake system
♦ 01 - Self-diagnosis compatible systems
♦ 03 - Brake electronics.
– Select required function on the display:
♦ J104 Control unit for ABS/ASR/ESP
♦ J104 Control unit for ABS/ASR/ESP, functions.
– Then carry out ESP road test and system test.

6.2 Removing and installing ESP bracket

The bracket securing hydraulic unit -N55- and control unit -J104-
cannot be removed.

26 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

7 Speed sensors of ABS/ESP system - overview

Illustration shows front right of vehicle.

1 - Speed sensor -G45- / -G47-

2 - Hexagon socket head bolt
❑ 9 Nm

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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.

7.1 Removing and installing front speed

sensors -G45- / -G47-

Note

The sensor ring/rotor is incorporated in the corresponding wheel

bearing unit and cannot be renewed.

Removing
– Raise vehicle.
– Remove wheels.

7. Speed sensors of ABS/ESP system - overview 27

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Release connector -1- at speed sensor and unplug.

– Remove bolt -2-.
– Pull speed sensor out of wheel bearing housing.
Installing
Installation is performed in reverse sequence; note the following:
– Before inserting speed sensor, clean inner surface of hole and
coat speed sensor thoroughly with lubricating paste
G 000 650. 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
– After installation, turn steering to full left and right
with respect lock andof information in this document. Copyright by AUDI AG.
to the correctness
check clearance of speed sensor wire.
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.

7.2 Removing and installing rear speed sensors -G44- / -G46-

Illustration shows rear left of vehicle.

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1 - Speed sensor -G44- / -G46-
2 - Hexagon socket head bolt
❑ 9 Nm

Note

The sensor ring/rotor is incorporated in the corresponding wheel

bearing unit and cannot be renewed.

Removing
– Raise vehicle.

28 Rep. Gr.45 - Anti-lock brake system

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Release connector -1- at speed sensor and unplug.

– Remove bolt -2-.
– Pull speed sensor out of wheel bearing housing.
Installing
Installation is performed in reverse sequence; note the following:
– Before inserting speed sensor, clean inner surface of hole and
coat speed sensor thoroughly with lubricating paste
G 000 650.
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.

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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. Speed sensors of ABS/ESP system - overview 29

 Audi A4 2008 ➤
Brake system - Edition 11.2007

46 – Brakes - mechanism
1 Front brakes FN3-57 - exploded view

Note

♦ Install all parts supplied in repair kit.

♦ After replacing brake pads, depress brake pedal firmly several
times with vehicle stationary so that the pads are properly
seated inProtected
their normal operating
by copyright. position.
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
♦ To draw offwith
brake
respectfluid
to thefrom brake
correctness fluid reservoir
of information use aCopyright
in this document. bleeder by AUDI AG.
bottle which is used only for brake fluid. Brake fluid is poison‐
ous and must on no account be sucked out with the mouth
using a hose!

1 - Splash plate for brakes

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2 - Bolt
❑ 18 Nm
3 - Spring
❑ Must be seated in brake
piston
4 - Connector
❑ When renewing pads,
remove from bracket
5 - Bolt
❑ 190 Nm
6 - Brake carrier
❑ Bolt to wheel bearing
housing
7 - Brake pads
❑ Wear limit ⇒ page 1

Note

❑ Before inserting pads,

clean guide surfaces
and apply a thin coating
of polycarbamide
grease -G 052 142 A2- .

Note

❑ Brake pad wear indica‐

tor at front left
❑ Warning lamp in instru‐
ment cluster comes on
when wear limit is
reached
❑ Always renew on both sides of axle
❑ Removing and installing ⇒ page 37
❑ Checking pad thickness: ⇒ Maintenance ; Booklet 811
❑ Different versions available ⇒ ETKA

30 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

8 - Retaining spring
❑ Before inserting pads, clean guide surfaces and apply a thin coating of polycarbamide grease -G 052
142 A2- .
❑ Insert in both holes in brake caliper housing

Note

9 - Brake disc
❑ Wear limit ⇒ page 1
❑ Always renew on both sides of axle
❑ Detach brake caliper prior to removing
❑ Removing and installing ⇒ page 40
10 - Bolt
❑ 5 Nm
11 - Brake caliper housing

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❑ Unscrew from brake carrier to replace brake pads
❑ Servicing brake caliper ⇒ page 134
12 - Guide pin
❑ 30 Nm
13 - Protective cap
❑ Detach when removing guide pins
❑ Re-install after fitting guide pins
14 - Brake hose
❑ Do not disconnect brake hose when changing brake pads
❑ Screw into brake caliper housing
❑ 12 Nm at brake caliper connection

1.1 Removing and installing front brake cal‐

iper with brake carrier - FN-3 brakes
Always use new bolts ⇒ ETKA .
Detaching
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1332-
♦ Ratchet -V.A.G. 1332/1-
– Raise vehicle.
– Remove wheels.
– Detach brake
Protected by hose
copyright. from
Copying bracket.
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
– Unplug brake
with respect pad
to the wear ofindicator
correctness on
information in thisbrake caliper
document. (left-side).
Copyright by AUDI AG.

– Remove bolts -5- on brake carrier.

1. Front brakes FN3-57 - exploded view 31

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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

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

– Detach brake carrier with pads and caliper.

Do not leave brake caliper and brake carrier hanging from brake
hose but secure them to bodywork using a suitable cable tie or
wire. Take care that brake hose is not damaged by weight of brake
components.

WARNING

Do not apply brake when brake caliper is removed.

Installing
Always use new bolts ⇒ ETKA .
– Carefully press brake caliper and brake carrier (with brake
pads fitted) over brake disc.
– Secure brake carrier with new bolts -5-.

32 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
– Fit brake hose in bracket.
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

1.2 Renewing front brake caliper - FN-3

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.
brakes
Always use new bolts ⇒ ETKA .
Removing
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1332-
♦ Ratchet -V.A.G. 1332/1-
♦ Torque wrench -V.A.G 1331-
♦ Ratchet -V.A.G. 1331/1-
♦ Brake pedal actuator -V.A.G 1869/2-

1. Front brakes FN3-57 - exploded view 33

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Insert brake pedal actuator -V.A.G 1869/2- between brake

pedal and driver's seat (depress brake pedal at least 60 mm).
This closes the valves in the brake master cylinder and stops
the brake fluid reservoir from running empty.
– Raise vehicle.
– Remove wheels.
– Connect hose of bleeder bottle to bleeder screw of front brake
caliper.
– Open bleeder screw on front brake caliper to release pressure
from brake system.
– Close bleeder screw.

Note
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
Do not remove brake
with respect to thepedal actuator
correctness -V.A.G
of information 1869/2-Copyright
in this document. . by AUDI AG.

– Remove brake pads ⇒ page 37 .

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Note

♦ Mark brake pads when removing them if they are to be rein‐

stalled. Reinstall in their original position to prevent uneven
braking.
♦ The brake disc is secured with a bolt.

– Disconnect brake hose from brake caliper.

– Remove brake caliper from vehicle.
– Remove bolts -5- on brake carrier, holding brake carrier firmly.

34 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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– Detach brake carrier.
Installing
Always use new bolts ⇒ ETKA .
– Fit brake carrier.
– Secure brake carrier with new bolts -5-.

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. Front brakes FN3-57 - exploded view 35

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
– Connect brake hose to caliper and tighten connection.
– Install brake pads ⇒ page 37 .

Note

After each brake pad change firmly depress brake pedal several
times with vehicle stationary, so that the brake pads are properly
seated in their normal operating position.

– Remove brake pedal actuator -V.A.G 1869/2- .

– Bleed brake system ⇒ page 151 .
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

36 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

1.3 Removing and installing front brake

pads - FN-3 brakes

Note

Always renew on both sides of axle.

Special tools and workshop equipment required

♦ Torque wrench -V.A.G 1331-
♦ Ratchet -V.A.G. 1331/1-
♦ Piston resetting appliance -T10145-
Removing
– Raise vehicle.
– Remove wheels.

Note

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Mark brake pads when removing them if they are to be reinstalled.
Reinstall in their original position to prevent uneven braking.

– Remove protective caps -13-.

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. Front brakes FN3-57 - exploded view 37

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
– On vehicles equipped with a brake pad wear indicator, unplug
connector -4- at front left.
– Slightly lift up locating lug on lower part of connector and turn
90°.
– Pull lower part of connector for wear indicator out of bracket.
– Lever brake pad retaining spring out of brake caliper housing
with a screwdriver and remove.

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.

38 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Unscrew and remove both guide pins -12- from brake caliper.
Tie brake caliper up to vehicle using a suitable wire. Take care
that brake hose is not damaged by weight of brake components.
– Take brake pads out of brake caliper housing or from brake
carrier.

WARNING

Do not apply brake when brake caliper is removed.

Installing
– Clean brake caliper housing.
Only use methylated spirits
Protected to clean the
by copyright. brake
Copying caliper
for private housing.
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.

Note

Before inserting new brake pads, press piston back into cylinder
with resetting appliance. Before pressing the piston back, draw

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off brake fluid from the reservoir with a bleeder bottle. Otherwise,
brake fluid can overflow and cause damage.

WARNING

Brake fluid is poisonous and must NOT be sucked through a

hose with the mouth.

– Press piston back.

Use piston resetting appliance T10145.

– Insert brake pad with retaining spring in brake caliper housing

(piston).

Note

The inner pad (with spring) has an arrow. The arrow must point
in direction of brake disc rotation when moving forwards. May
create noises if incorrectly installed.

– If fitted, pull protective foil off pad backplates.

– Fit outer brake pad onto brake carrier.

1. Front brakes FN3-57 - exploded view 39

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Screw both guide pins into brake caliper housing and tighten.

– Fit both protective caps -arrow-.

– Insert retaining spring into brake caliper housing.

Note

♦ The retaining spring must be pressed under the brake carrier

after inserting into both holes. If incorrectly installed, the wear

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of the outer pad cannot be adjusted, and the pedal travel will
be increased as a result.
♦ After installing the brake pads, depress pedal firmly several
times with the vehicle stationary, so that the brake pads are
properly seated in their normal operating position.

– Check brake fluid level and top up if necessary.

1.4 Removing and installing front brake disc

- FN-3 brakes
Detaching
– Raise vehicle.
– Remove wheels.
– Detach front brake caliper with pads and brake carrier
⇒ page 31 .

WARNING

Do not apply brake when brake caliper is removed.

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.

40 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Do not leave brake caliper and brake carrier hanging from brake
hose but secure them to bodywork using a suitable cable tie or
wire. Take care that brake hose is not damaged by weight of brake
components.
– Remove locating bolt -arrow- from brake disc, holding brake
disc in position.
– Remove brake disc.

Note

Take care to keep the brake disc straight when taking it off the
wheel hub.

Installing
Clean brake disc, wheel hub and contact surfaces before instal‐
ling.
– Fit brake disc onto wheel hub.

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Note

Take care to keep the brake disc straight when fitting it onto the
wheel hub.

– Screw in locating bolt -arrow- and tighten.

– Install front brake caliper with pads and brake carrier
⇒ page 31 .
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

1.5 Renewing front brake disc - FN-3 brakes

Always use new bolts ⇒ ETKA .

Note

Always renew on both sides of axle. 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.
Removing
– Raise vehicle.
– Remove wheels.
– Remove front brake pads ⇒ page 37 .

1. Front brakes FN3-57 - exploded view 41

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Do not leave brake caliper hanging from brake hose but secure it
to bodywork using a suitable cable tie or wire. Take care that
brake hose is not damaged by weight of brake components.

WARNING

Do not apply brake when brake caliper is removed.

– Remove bolts -5- on front brake carrier.

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.

cardiagn.com
– Detach front brake carrier.

42 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Remove locating bolt -arrow- from brake disc, holding brake

disc in position.
– Remove brake disc.

Note

Take care to keep the brake disc straight when taking it off the
wheel hub.

Installing
Always use new bolts ⇒ ETKA .
Clean brake disc, wheel hub and contact surfaces before instal‐
ling.
– Fit brake disc onto wheel hub.

Note

Take care to keep the brake disc straight when fitting it onto the

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wheel hub.
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.
– Screw in locating bolt -arrow- and tighten.
– Fit front brake carrier.
– Fit bolts -5- on front brake carrier and tighten to specified tor‐
que.

1. Front brakes FN3-57 - exploded view 43

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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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.

– Install front brake pads ⇒ page 37 .

Note

After each brake pad change firmly depress brake pedal several
times with vehicle stationary, so that the brake pads are properly
seated in their normal operating position.

– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

1.6 Removing and installing front splash

plate - FN-3 brakes
Removing
– Raise vehicle.
– Remove wheels.
– Detach front brake disc ⇒ page 40 .
– Remove bolts -2- from splash plate.

44 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
– Detach splash plate.
Installing
– Installation is carried out in reverse sequence.
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. Protected
44 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. Front brakes FN3-57 - exploded view 45

 Audi A4 2008 ➤
Brake system - Edition 11.2007

2 Front brakes FBC-57 - exploded view

Note

♦ Install all parts supplied in repair kit.

♦ After replacing brake pads, depress brake pedal firmly several
times with vehicle stationary so that the pads are properly
seated in their normal operating position.
♦ To draw off brake fluid from brake fluid reservoir use a bleeder
bottle which is used only for brake fluid. Brake fluid is poison‐
ous and must on no account be sucked out with the mouth
using a hose!
♦ Check that the brake caliper moves
Protected freelyCopying
by copyright. by moving
for private it
or from
commercial purposes, in part or in whole, is not
side to side. 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 - Brake pads
❑ Wear limit ⇒ page 1

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❑ Illustration shows front
left of vehicle with elec‐
trical wire for pad wear
indicator

Note

An electrical wire for the pad wear

indicator is fitted to the left-side in‐
ner pad (with spring).
❑ Always renew on both
sides of axle
❑ Before inserting pads,
clean guide surfaces
and apply a thin coating
of polycarbamide
grease -G 052 142 A2- .
❑ Removing and installing
⇒ page 52
❑ Checking pad thick‐
ness: ⇒ Maintenance ;
Booklet 405
❑ Different versions avail‐
able ⇒ ETKA

Note

Clean the brake caliper thoroughly

(grease-free) before inserting new
brake pads. It is particularly impor‐
tant to ensure that contact surfaces
for brake pads are clean.

2 - Brake carrier
❑ Bolt to wheel bearing housing
❑ The retaining pins for the brake pads in the brake carrier must NOT be slackened
3 - Bolt
❑ Brake carrier to wheel bearing housing
❑ Use new bolts ⇒ ETKA

46 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

❑ 196 Nm
4 - Bolt
❑ Secure brake caliper to brake carrier
❑ 30 Nm
5 - Brake line connection on brake caliper
❑ 20 Nm
6 - Bolt
❑ These bolts (4x) must NOT be slackened
7 - Brake caliper housing
❑ If assembly work is required, do not leave caliper hanging from brake hose but secure it to bodywork
with binding wire
❑ Brake caliper must not be dismantled
❑ With the exception of “Removing and installing brake pads” ⇒ page 52 , “Servicing front brake caliper”
and renewing guide pins, no repairs may be performed on the brake caliper
❑ Do not twist hose when fitting
8 - Spring clip Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
❑ Must be removed before removing brake
permitted unless pads
authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

cardiagn.com
with respect to the correctness of information in this document. Copyright by AUDI AG.
❑ Install after fitting brake pads
9 - Retaining pin for brake pads
❑ Do not slacken

WARNING
The retaining pins (4x)
for the brake pads on the
brake carrier must NOT
be slackened

10 - Locating device for brake pad in caliper

11 - Brake disc
❑ Wear limit ⇒ page 1
❑ Always renew on both sides of axle
❑ Removing and installing ⇒ page 60
❑ Lubricate contact surfaces between brake disc and wheel hub with polycarbamide grease -G 052 142
A2- . ⇒ Wheels and tyres; Rep. Gr. 44
❑ Allocation
❑ Thickness
12 - Bolt for brake disc
❑ 5 Nm

2.1 Removing and installing front brake cal‐

iper with brake carrier - FBC-57 brakes
Use new bolts ⇒ ETKA .
Detaching

WARNING

The retaining pins (4x) for the brake pads on the brake carrier
must NOT be slackened

2. Front brakes FBC-57 - exploded view 47

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Special tools and workshop equipment required

♦ Torque wrench -V.A.G 1332-
♦ Ratchet -V.A.G. 1332/1-
– Raise vehicle.
– Remove wheels.
– Move brake hose clear from bracket -4-.

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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.

– Release electrical wire towards the left -arrow A- from bracket

-2- and detach.
– Remove bolts -1- on brake carrier.
– Detach brake caliper with pads and brake carrier.
Do not leave brake caliper and brake carrier hanging from brake
hose but secure them to bodywork using a suitable cable tie or
wire. Take care that brake hose is not damaged by weight of brake
components.

WARNING

Do not apply brake when brake caliper is removed.

Installing
Use new bolts ⇒ ETKA .
– Carefully press brake caliper and brake carrier (with brake
pads fitted) over brake disc.
– Secure brake carrier with new bolts -1-.
– Fit brake hose in bracket -4-.

48 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Fit electrical wire -2- in bracket and turn to the right -arrow B-
to secure.
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.

2.2 Renewing front brake caliper - FBC-57

brakes
Use new bolts ⇒ ETKA .
Removing

WARNING

The retaining pins (4x) for the brake pads on the brake carrier
must NOT be slackened

Special tools and workshop equipment required

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♦ Torque wrench -V.A.G 1332-
♦ Ratchet -V.A.G. 1332/1-
♦ Torque wrench -V.A.G 1331-
♦ Ratchet -V.A.G. 1331/1-
♦ Brake pedal actuator -V.A.G 1869/2-
♦ Piston resetting appliance -T10145-
– Insert brake pedal actuator -V.A.G 1869/2- between brake
pedal and driver's seat (depress brake pedal at least 60 mm).
This closes the valves in the brake master cylinder and stops
the brake fluid reservoir from running empty.
– Raise vehicle.
– Remove wheels.
– Connect hose of bleeder bottle to bleeder screw of front brake
caliper.
– Open bleeder screw on front brake caliper to release pressure
from brake system.
– Close bleeder screw.

Note

Do not remove brake pedal actuator -V.A.G 1869/2- .

– Disconnect brake pressure line from caliper.

– Remove brake pads ⇒ page 52 .
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

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

Mark brake pads when removing them if they are to be reinstalled.

Reinstall in their original position to prevent uneven braking.

– Remove brake caliper -7- from vehicle.

2. Front brakes FBC-57 - exploded view 49

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
Caution

Do NOT slacken bolts -6 and 9-

– Remove bolts -3- on brake carrier, holding brake carrier firmly.

– Detach brake carrier.
Installing
Use new bolts ⇒ ETKA .
– Fit brake carrier.
– Secure brake carrier with new bolts -3-.

50 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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.

– Install brake pads ⇒ page 52 .

Note

After each brake pad change firmly depress brake pedal several
times with vehicle stationary, so that the brake pads are properly
seated in their normal operating position.

– Connect brake pressure line -5- to caliper and tighten con‐

nection.

2. Front brakes FBC-57 - exploded view 51

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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 brake pedal actuator -V.A.G 1869/2- .

– Bleed brake system ⇒ page 151 .
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

2.3 Removing and installing front brake

pads - FBC-57 brakes

Note

Always renew on both sides of axle.

Special tools and workshop equipment required

♦ Torque wrench -V.A.G 1331-
♦ Ratchet -V.A.G. 1331/1-
♦ Piston resetting appliance -T10145-

52 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Removing

WARNING

The retaining pins (4x) for the brake pads on the brake carrier
must NOT be slackened

– Raise vehicle.
– Remove wheels.

Note

Mark brake pads when removing them if they are to be reinstalled.

Reinstall in their original position to prevent uneven braking.

– Move brake hose clear from bracket -4-.

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– Release electrical wire towards the left -arrow A- from bracket
-2- and detach.

WARNING

The four retaining pins for the brake pads in the brake caliper
must NOT be slackened.
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 down centre of retaining spring -8-.

2. Front brakes FBC-57 - exploded view 53

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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.

Note

♦ The spring is under tension; hold your hand over the spring to
avoid risk of injury.
♦ When removing the spring, take care not to scratch or chip the
paint on the brake caliper.

– Carefully detach retaining spring.

– Unplug electrical connector for brake pad wear indicator (front
left).

Note

The pad wear indicator is only fitted on the inner pad in the front
left brake caliper.

– Unscrew both bolts -4- for guide pins and remove from brake
caliper.

54 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
Caution

Do NOT slacken bolts -6 and 9-

– Pull both guide pins slightly out of brake caliper to facilitate

removal of caliper.
– Detach brake caliper.
Do not leave brake caliper hanging from brake
Protected hose but
by copyright. secure
Copying it or commercial purposes, in part or in whole, is not
for private
to bodywork using a suitable cable tiepermitted
or wire. Take
unless carebythat
authorised AUDI AG. AUDI AG does not guarantee or accept any liability
brake hose is not damaged by weight of brake
with respect components.
to the correctness of information in this document. Copyright by AUDI AG.

– Take brake pads out of brake caliper housing or from brake

carrier.

WARNING

The four retaining pins for the brake pads in the brake caliper
must NOT be slackened.

2. Front brakes FBC-57 - exploded view 55

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Installing
– Clean brake caliper.
Only use methylated spirits to clean the brake caliper housing.

Note

Before inserting new brake pads, press piston back into cylinder
with resetting appliance. Before pressing the piston back, draw
off brake fluid from the reservoir with a bleeder bottle. Otherwise,
fluid can overflow and cause damage, particularly if reservoir has
been topped up.

WARNING

Brake fluid is poisonous and must NOT be sucked through a

hose with the mouth.

– Press piston back.

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Use piston resetting appliance T10145.
– If fitted, pull protective foil off pad backplates.

– Fit inner brake pad with retaining spring in brake caliper. Re‐
taining spring -arrow- must be seated in brake piston.

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.

– Fit outer brake pad -2- in brake caliper.

– Press brake pad into caliper and insert locating device into
aperture in brake caliper.

56 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
The backplate of the brake pad has a locating device -10-, which
must fit securely in the aperture in the caliper.

WARNING

Both brake pads must be seated under the retaining pins in the
caliper. The brake caliper has two retaining pins on each side,
which must not be slackened.

– Carefully fit brake caliper (with brake pads) over brake disc.
– Secure brake caliper to brake carrier with both guide pins
-4-. 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.

2. Front brakes FBC-57 - exploded view 57

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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.

– Fit retaining spring -8- on outer brake pad.

58 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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 down centre of retaining spring -8-toand
with respect fit centre
the correctness tab of in this document. Copyright by AUDI AG.
of information
spring in hole -arrow- in brake caliper.
The tab of the retaining spring must be seated properly in the hole
in the brake caliper, otherwise the spring can become detached
and the pad would not be secured.

Note

♦ The spring is under tension; hold your hand over the spring to
avoid risk of injury.
♦ When fitting the spring, take care not to scratch or chip the
paint on the brake caliper.

– Attach electrical connector for pad wear indicator in bracket

(front left).

2. Front brakes FBC-57 - exploded view 59

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Fit electrical wire -2- in bracket and turn to the right -arrow B-
to secure.
– Fit brake hose in bracket -4-.
– Plug in electrical connector for brake pad wear indicator (front
left).
– Fit wheels ⇒ Wheels and tyres; Rep. Gr. 44 .

Note

After installing the brake pads, depress pedal firmly several times
with the vehicle stationary, so that the brake pads are properly
seated in their normal operating position.

– Check brake fluid level and top up if necessary.

2.4 Removing and installing front brake disc

- FBC-57 brakes
Detaching

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WARNING

The retaining pins (4x) for the brake pads on the brake carrier
must NOT be slackened

– Raise vehicle.
– Remove wheels.
– Detach front brake caliper with pads and brake carrier
⇒ page 47 .
Do not leave brake caliper and brake carrier hanging from brake
hose but secure them to bodywork using a suitable cable tie or
wire. Take care that brake hose is not damaged by weight of brake
components.
– Remove locating bolt -arrow- from brake disc, holding brake
disc in position.
– Remove brake disc.

Note

Take care to keep the brake disc straight when taking it off the
wheel hub.

Installing
Clean brake disc, wheel hub and contact surfaces before instal‐
ling.
– Fit brake disc onto wheel hub.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Note 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.

Take care to keep the brake disc straight when fitting it onto the
wheel hub.

60 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Screw in locating bolt -arrow- and tighten.

– Install front brake caliper with pads and brake carrier
⇒ page 47 .
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

2.5 Renewing front brake disc - FBC-57

brakes
Use new bolts ⇒ ETKA .

Note

cardiagn.com
Always renew on both sides of axle.

Removing

WARNING

The retaining pins (4x) for the brake pads on the brake carrier
must NOT be slackened

– Raise vehicle.
– Remove wheels.
– Remove front brake pads ⇒ page 52 .
Do not leave brake caliper hanging from brake hose but secure it
to bodywork using a suitable cable tie or wire. Take care that
brake hose is not damaged by weight of brake components.
– Remove bolts -3- on front brake carrier.

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.

2. Front brakes FBC-57 - exploded view 61

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
Caution

Do NOT slacken bolts -6 and 9-

– Detach front brake carrier.

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.

62 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Remove locating bolt -arrow- from brake disc, holding brake

disc in position.
– Remove brake disc.

Note

Take care to keep the brake disc straight when taking it off the
wheel hub.

Installing
Use new bolts ⇒ ETKA .
Clean brake disc, wheel hub and contact surfaces before instal‐
ling.
– Fit brake disc onto wheel hub.

Note

Take care to keep the brake disc straight when fitting it onto the

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wheel hub.

– ScrewProtected
in locating bolt Copying
by copyright. -arrow- and tighten.
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
– Fit front with
brake carrier.
respect to the correctness of information in this document. Copyright by AUDI AG.

Note

Take care to keep brake carrier straight when fitting

2. Front brakes FBC-57 - exploded view 63

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
– Fit bolts -3- on front brake carrier and tighten to specified tor‐
que.
– Install front brake pads ⇒ page 52 .

Note

After each brake pad change firmly depress brake pedal several
times with vehicle stationary, so that the brake pads are properly
seated in their normal operating position.

– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

64 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

2.6 Removing and installing front splash

plate - FBC-57 brakes
Removing

WARNING

The retaining pins (4x) for the brake pads on the brake carrier
must NOT be slackened

– Raise vehicle.
– Remove wheels.
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
– Detach front brake disc to⇒the
with respect page 60 . of information in this document. Copyright by AUDI AG.
correctness

– Remove bolts on splash plate.

– Detach splash plate.
Installing
– Installation is carried out in reverse sequence.

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– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

2. Front brakes FBC-57 - exploded view 65

 Audi A4 2008 ➤
Brake system - Edition 11.2007

3 Rear brakes with electronic parking

brake - exploded view
Rear brakes with automatic adjustment

Note

Install all parts supplied in repair kit.

1 - Self-locking bolt
❑ 12 Nm
2 - Actuator motor for electron‐
ic parking brake and hand‐
brake
❑ Removing and installing
control unit for electron‐
ic parking brake and
handbrake ⇒ page 126

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❑ Removing and installing
actuator motor
⇒ page 127
3 - Seal
❑ Always renew
4 - Self-locking bolt
❑ 35 Nm
❑ Always renew
❑ When loosening and
tightening, counter-hold
on guide pin
5 - Spacer bracket
6 - Brake hose
❑ Connection to brake cal‐
iper, 12 Nm
❑ Do not disconnect brake
line when changing
brake pads
❑ Make sure that the lock‐
ing lugs are fitted prop‐
erly in the bracket
❑ Do not twist hose when
installing
7 - Brake caliper housing
❑ Do not disconnect brake hose when changing brake pads
❑ Servicing brake calipers
❑ The brake carrier can be mounted together with the brake caliper
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
8 - Brake carrier with guide pins and protective caps
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.
❑ Replacement carriers are supplied assembled and with sufficient grease on guide pins
❑ If protective caps or guide pins are damaged, renew using repair kit. Use grease sachet supplied to
lubricate guide pins.
❑ The brake carrier can be mounted together with the brake caliper
9 - Brake pads
❑ Wear limit ⇒ page 1

66 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

❑ Always renew on both sides of axle

❑ Removing and installing ⇒ page 78
❑ Checking pad thickness: ⇒ Maintenance ; Booklet 405
❑ The brake carrier can be mounted together with the brake caliper

Note

The brake pads must be seated be‐

tween the two retaining lugs on the
pad retainer to help maintain the re‐
quired clearance between pads and
disc

10 - Pad retainer
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
❑ Always
with respectrenew when changing
to the correctness pads
of information in this document. Copyright by AUDI AG.

Note

The brake pads must be seated be‐

tween the two retaining lugs on the
pad retainer to help maintain the re‐
quired clearance between pads and

cardiagn.com
disc

11 - Wheel bolts
❑ Fitting wheels ⇒ Wheels and tyres; Rep. Gr. 44
12 - Bolt
❑ 5 Nm
13 - Brake disc
❑ Wear limit ⇒ page 1
❑ Removing and installing ⇒ page 83
❑ Always renew on both sides of axle
❑ Allocation of brake discs ⇒ page 1
14 - Hexagon bolts
❑ 10 Nm
15 - Splash plate for brakes
❑ Removing and installing ⇒ page 87
16 - Bolt
❑ 100 Nm + 90°
❑ Renew
17 - Bolts
❑ 100 Nm + 90°
❑ Renew

3.1 Removing and installing rear brake cal‐

iper with brake carrier
Detaching
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1332-
♦ Ratchet -V.A.G. 1332/1-
♦ Vehicle diagnosis, testing and information system -VAS
5051B- or -VAS 5052-

3. Rear brakes with electronic parking brake - exploded view 67

 Audi A4 2008 ➤
Brake system - Edition 11.2007

♦ Ratchet adapter
– With ignition switched off, connect vehicle diagnostic, testing
and information system -VAS 5051B- or -VAS 5052- to 16-pin
diagnostic connector in vehicle.

cardiagn.com
Note

♦ Ignition on
♦ Parking brake released
♦ Coding checked and rectified if necessary
♦ Fault memory interrogated, indicated faults eliminated and
fault memory erased.

– Select function “053 - Parking brake”.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Select function “006unless
permitted - Basic setting”.
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.

68 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Display on vehicle diagnosis, testing and information system :

♦ The prompt to enter a display group appears in display zone
-1-.
♦ Display zone -2- shows a keypad.
– Enter “007” as “display group number” via the keypad in dis‐
play zone -2- and confirm entry with the “Q” key. (resetting
piston).
– Press the green arrow button (bottom left) to exit from the
input mask.
– Raise vehicle.
– Remove wheels.
– Unplug electrical connector for parking brake.
– Unclip brake hose from retainer on hub carrier
– Remove bolts -16 and 17- on brake carrier.

cardiagn.com
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.

– Detach brake caliper with pads and brake carrier.

Do not leave brake caliper and brake carrier hanging from brake
hose but secure them to bodywork using a suitable cable tie or

3. Rear brakes with electronic parking brake - exploded view 69

 Audi A4 2008 ➤
Brake system - Edition 11.2007

wire. Take care that brake hose is not damaged by weight of brake
components.

WARNING

Do not press the footbrake or apply the electronic parking

brake when the brake caliper is removed.

Installing
Use new bolts ⇒ ETKA .
– Carefully press brake caliper and brake carrier (with brake
pads fitted) over brake disc.
– Secure brake carrier with new bolts -16 and 17-.

cardiagn.com
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.

Note

Use extension (commercially available) to tighten bottom bolt

-16-. Top bolt -17- can be tightened without extension. Wheel
housing liner must be slightly pressed aside.

70 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

Do not attach electrical connector for parking brake until after

tightening bolts.

– Plug in electrical connection for parking brake.

– Clip brake hose into retainer on hub carrier.

Note

Make sure that brake hose is properly clipped into retainer on hub
carrier and securely seated. Otherwise, there is a risk that the
brake hose will not remain in the retainer.

– Fit wheels.
– Lower vehicle.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44

cardiagn.com
– With ignition switched off, connect vehicle diagnostic, testing
and information system -VAS 5051B- or -VAS 5052- to 16-pin
diagnostic connector in vehicle.

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. Rear brakes with electronic parking brake - exploded view 71

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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 on vehicle diagnosis, testing and information system :

♦ The prompt to enter a display group appears in display zone
-1-.
♦ Display zone -2- shows a keypad.
– Enter “006” as “display group number” via the keypad in dis‐
play zone -2- and confirm entry with the “Q” key. (Moving
piston to original position).
– Press the green arrow button (bottom left) to exit from the
input mask.

72 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

3.2 Renewing rear brake caliper

Use new bolts ⇒ ETKA .

Note

The actuator motor does not have to be removed when renewing

the rear brake caliper. The new brake caliper is supplied complete
with a new actuator motor.

Removing
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1331-
♦ Ring spanner insert -V.A.G. 1331/3-
♦ Brake pedal actuator -V.A.G 1869/2-
♦ Vehicle diagnostic, testing and information system
– With ignition switched off, connect vehicle diagnostic, testing
and information system -VAS 5051B- or -VAS 5052- to 16-pin

cardiagn.com
diagnostic connector in vehicle.

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. Rear brakes with electronic parking brake - exploded view 73

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

♦ Ignition on
♦ Parking brake released
♦ Coding checked and rectified if necessary
♦ Fault memory interrogated, indicated faults eliminated and
fault memory erased.

– Select function “053 - Parking brake”.

– Select function “006 - Basic setting”.
Display on vehicle diagnosis, testing and information system :
♦ The prompt to enter a display group appears in display zone
-1-.
♦ Display zone -2- shows a keypad.
– Enter “007” as “display group number” via the keypad in dis‐
play zone -2- and confirm entry with the “Q” key. (resetting

cardiagn.com
piston).
– Press the green arrow button (bottom left) to exit from the
input mask.

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.

74 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Insert brake pedal actuator -V.A.G 1869/2- between brake

pedal and driver's seat (depress brake pedal at least 60 mm).
This closes the valves in the brake master cylinder and stops
the brake fluid reservoir from running empty.
– Raise vehicle.
– Remove wheels.
– Connect the hose of a bleeder bottle to bleeder screw of rear
brake caliper.
– Open bleeder screw on rear brake caliper to release pressure
from brake system.
– Close bleeder screw.

Note

Do not remove brake pedal actuator -V.A.G 1869/2- .

– Unplug electrical connector for parking brake.

– Unclip brake hose from retainer on hub carrier

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– Remove rear brake pads ⇒ page 78 .

Note

♦ Mark brake pads when removing them if they are to be rein‐

stalled. Fit in same position when installing otherwise uneven
braking will be caused.
♦ It is recommended to apply the electronic parking brake again
after driving long distances.
♦ The clearance between brake disc and brake pad is adjusted
automatically approx. every 1000 km, unless the EPB is op‐
erated while covering this distance.

– Disconnect brake pressure line from caliper.

– Remove brake caliper from vehicle.

Note
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 actuator motor does not have to be removed when renewing
the rear brake caliper. The new brake caliper is supplied complete
with a new actuator motor.

Installing
Use new bolts ⇒ ETKA .
– Connect brake pressure line to caliper and tighten connection.
– Install rear brake pads ⇒ page 78 .
– Secure brake caliper with new bolts -4-.

3. Rear brakes with electronic parking brake - exploded view 75

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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.

Use torque wrench -V.A.G 1331- with ring spanner insert -V.A.G
1331/3- to tighten bolts -4-.

Note

Do not attach electrical connector for parking brake until after

tightening bolts.

– Plug in electrical connection for parking brake.

– Clip brake hose into retainer on hub carrier.

Note

Make sure that brake hose is properly clipped into retainer on hub
carrier and securely seated. Otherwise, there is a risk that the
brake hose will not remain in the retainer.

76 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

After each brake pad change firmly depress brake pedal several
times with vehicle stationary, so that the brake pads are properly
seated in their normal operating position.

– Remove brake pedal actuator -V.A.G 1869/2- .

– Bleed brake system ⇒ page 151 .
– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.
– With ignition switched off, connect vehicle diagnostic, testing
and information system -VAS 5051B- or -VAS 5052- to 16-pin
diagnostic connector in vehicle.

cardiagn.com
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. Rear brakes with electronic parking brake - exploded view 77

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Display on vehicle diagnosis, testing and information system :

♦ The prompt to enter a display group appears in display zone
-1-.
♦ Display zone -2- shows a keypad.
– Enter “006” as “display group number” via the keypad in dis‐
play zone -2- and confirm entry with the “Q” key. (Moving
piston to original position).
– Press the green arrow button (bottom left) to exit from the
input mask.

3.3 Removing and installing rear brake pads

Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1331-
♦ Ring spanner insert -V.A.G 1331/3-
♦ Vehicle diagnostic, testing and information system

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Removing

Note

♦ Mark brake pads when removing them if they are to be rein‐

stalled. Fit in same position when installing otherwise uneven
braking will be caused.
♦ It is recommended to apply the electronic parking brake again
after driving long distances.
♦ The clearance between brake disc and brake pad is adjusted
automatically approx. every 1000 km, unless the EPB is op‐
erated while covering this distance.

– With ignition switched off, connect vehicle diagnostic, testing

and information system -VAS 5051B- or -VAS 5052- to 16-pin
diagnostic connector in vehicle.

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.

78 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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.

Note

♦ Ignition on
♦ Parking brake released
♦ Coding checked and rectified if necessary
♦ Fault memory interrogated, indicated faults eliminated and
fault memory erased.

– Select function “053 - Parking brake”.

– Select function “006 - Basic setting”.

3. Rear brakes with electronic parking brake - exploded view 79

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Display on vehicle diagnosis, testing and information system :

♦ The prompt to enter a display group appears in display zone
-1-.
♦ Display zone -2- shows a keypad.
– Enter “007” as “display group number” via the keypad in dis‐
play zone -2- and confirm entry with the “Q” key. (resetting
piston).
– Press the green arrow button (bottom left) to exit from the
input mask.
– Raise vehicle.
– Remove wheels.
– Unplug electrical connector for parking brake.
– Unclip brake hose from retainer on hub carrier

– Remove securing bolts from brake caliper housing, when do‐

ing this counter-hold on guide pins.

cardiagn.com
Note

Do not apply tension on brake hose or electrical wiring.

– Detach brake caliper.

Do not leave brake caliper hanging from brake hose but secure it
to bodywork using a suitable cable tie or wire. Take care that
brake hose is not damaged by weight of brake components.

WARNING

Do not apply brake when brake caliper is removed.

– Remove brake pads.

– Remove pad retainers.
– Press piston back.

Use piston resetting appliance T10145.

Make sure that the brake piston remains straight when it is press‐
ed back.
Installing
Only use methylated spirits to clean the brake caliper housing.

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.

80 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Insert pad retaining springs.

– If fitted, pull protective foil off pad backplates.

– Fit brake pads.

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– Ensure that the brake pads are located correctly in the pad
retainers -arrows-.

Note

The brake pads must be seated between the two retaining lugs
on the pad retainer to help maintain the required clearance be‐
tween pads and disc.

– Install brake caliper.

Note

The repair kit includes new self-locking bolts which must be in‐
stalled in all cases.

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. Rear brakes with electronic parking brake - exploded view 81

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Secure brake caliper with new self-locking bolts.

Use torque wrench -V.A.G 1331- with ring spanner insert -V.A.G
1331/3- to tighten bolts.

Note

Do not attach electrical connector for parking brake until after

tightening bolts.

– Clip brake hose into retainer on hub carrier.

Note

Make sure that brake hose is properly clipped into retainer on hub
carrier and securely seated. Otherwise, there is a risk that the
brake hose will not remain in the retainer.

– Fit wheels.
– Lower vehicle.

cardiagn.com
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Check brake fluid level and top up if necessary.
– With ignition switched off, connect vehicle diagnostic, testing
and information system -VAS 5051B- or -VAS 5052- to 16-pin
diagnostic connector in vehicle.

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.

82 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
Display on vehicle diagnosis, testing and information system :
♦ The prompt to enter a display group appears in display zone
-1-.
♦ Display zone -2- shows a keypad.
– Enter “006” as “display group number” via the keypad in dis‐
play zone -2- and confirm entry with the “Q” key. (Moving
piston to original position).
– Press the green arrow button (bottom left) to exit from the
input mask.

3.4 Detaching and attaching rear brake disc

Detaching
– Raise vehicle.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Remove wheels. 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.
– Unclip brake hose from retainer on hub carrier
– Detach brake caliper with pads and brake carrier ⇒ page 67 .

3. Rear brakes with electronic parking brake - exploded view 83

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Do not leave brake caliper and brake carrier hanging from brake
hose but secure them to bodywork using a suitable cable tie or
wire. Take care that brake hose is not damaged by weight of brake
components.

WARNING

Do not apply brake when brake caliper is removed.

– Remove locating bolt -arrow- from brake disc, holding brake

disc in position.
– Take brake disc off wheel hub.
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.
Note

Take care to keep the brake disc straight when taking it off the
wheel hub.

Installing

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Clean brake disc, wheel hub and contact surfaces before instal‐
ling.
– Fit brake disc onto wheel hub.

Note

Take care to keep the brake disc straight when fitting it onto the
wheel hub.

– Screw in locating bolt -arrow- and tighten.

– Install brake caliper with brake carrier ⇒ page 67 .
– Clip brake hose into retainer on hub carrier.

Note

Make sure that brake hose is properly clipped into retainer on hub
carrier and securely seated. Otherwise, there is a risk that the
brake hose will not remain in the retainer.

– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.

3.5 Renewing rear brake disc

Removing
– Raise vehicle.
– Remove wheels.
– Unclip brake hose from retainer on hub carrier
– Remove rear brake pads ⇒ page 78 .
– Remove bolts -16 and 17- and detach brake carrier.

84 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

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– Remove locating bolt -arrow-, holding brake disc in position.
– Take brake disc off wheel hub.

Note

Take care to keep the brake disc straight when taking it off the
wheel hub.

Installing
Clean brake disc, wheel hub and contact surfaces before instal‐
ling.
– Fit brake disc onto wheel hub.

Note

Take care to keep the brake disc straight when fitting it onto the
wheel hub.

3. Rear brakes with electronic parking brake - exploded view 85

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Screw in locating bolt -arrow- and tighten.

– Install rear brake carrier. Fit bolts -16 and 17- and tighten.

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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.

Note

Use extension (commercially available) to tighten bottom bolt

-16-. Top bolt -17- can be tightened without extension. Wheel
housing liner must be slightly pressed aside.

– Install rear brake pads ⇒ page 78 .

– Plug in electrical connection for parking brake.

86 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Clip brake hose into retainer on hub carrier.

Note

Make sure that brake hose is properly clipped into retainer on hub
carrier and securely seated. Otherwise, there is a risk that the
brake hose will not remain in the retainer.

– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.

3.6 Removing and installing rear splash

plate
Removing
– Raise vehicle.
– Remove wheels.

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– Remove rear brake disc ⇒ page 83 .
– Remove bolts on splash plate.
– Detach splash plate.
Installing
– Fit splash plate.
– Screw in and tighten bolts on splash plate.
– Install rear brake disc ⇒ page 83 .
– Clip brake hose into retainer on hub carrier.

Note

Make sure that brake hose is properly clipped into retainer on hub
carrier and securely seated. Otherwise, there is a risk that the
brake hose will not remain in the retainer.

– Fit wheels.
Tightening torque for wheel bolts ⇒ Rep. Gr. 44
– Lower vehicle.

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. Rear brakes with electronic parking brake - exploded view 87

 Audi A4 2008 ➤
Brake system - Edition 11.2007

4 Brake pedal and mounting bracket -

exploded view

WARNING

The brake pedal travel must not be restricted by additional floor

coverings.

♦ Lubricate all bearings and contact surfaces with grease -G 000

450 02- .

1 - Mounting bracket for pedal

cluster
❑ Illustration for vehicle
with automatic gearbox
❑ Removing and instal‐
ling; vehicles with man‐
ual gearbox

cardiagn.com
⇒ page 104
❑ Removing and instal‐
ling; vehicles with auto‐
matic gearbox
⇒ page 116
2 - Sleeve
3 - Shaft for brake pedal
4 - Pivot pin
5 - Retaining clip (spring steel),
right-side
⇒ ETKA

6 - Washer
7 - Bolt for accelerator pedal
module
❑ 8 Nm
8 - Accelerator pedal module
9 - Bolt for pedal bracket
❑ 20 Nm
10 - Brake light sensor
❑ Removing and installing
⇒ page 14
11 - Bolt for pivot pin
❑ Bolt holds pivot pin in
position
❑ 8 Nm Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

12 - Retaining clip (spring steel), with

left-side
permitted 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.

⇒ ETKA

13 - Brake pedal
❑ Removing and installing; vehicles with manual gearbox ⇒ page 92
❑ Removing and installing; vehicles with automatic gearbox ⇒ page 95

88 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

WARNING
Stop on brake pedal
must always be fitted,
otherwise mounting for
brake light sensor can
break off when brake
pedal is released.

14 - Bearing shell is bonded to mounting

❑ For ball head of brake servo push rod
15 - Mounting
❑ For ball head of brake servo push rod
❑ With retaining lugs for ball head
❑ Removing and installing ⇒ page 100
16 - Nut
❑ 8 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
17 - Stop with respect to the correctness of information in this document. Copyright by AUDI AG.

cardiagn.com
WARNING
Stop on brake pedal
must always be fitted,
otherwise mounting for
brake light sensor can
break off when brake
pedal is released.

18 - Grommet
❑ Only fitted on vehicles with automatic gearbox

4.1 Separating and connecting brake pedal

and brake servo
Separating brake pedal from brake servo

WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break off when brake pedal is re‐
leased.

Special tools and workshop equipment required

♦ Release tool -T40168- for brake light sensor.

4. Brake pedal and mounting bracket - exploded view 89

 Audi A4 2008 ➤
Brake system - Edition 11.2007

♦ Release tool -T10006-

– Remove driver's storage compartment -1 ... 3-.

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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.

– Unplug electrical connector -C- on footwell vent.

– Remove footwell vent -A-B-.
– Remove brake light sensor ⇒ page 14 .

90 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– First press brake pedal towards brake servo and hold in this
position.
1 - Brake pedal
2 - Push rod
3 - Retaining lugs
– Insert release tool -T10006- as shown and pull towards driver's
seat, at the same time holding brake pedal in position (the
pedal must not move towards the rear). This will press the re‐
taining lugs -3- of the mounting off the ball head of the push
rod -2-.
For illustration purposes, the method of separating the brake ped‐
al from the brake servo is shown with the pedal cluster removed.
– Pull release tool -T10006- and brake pedal together towards
driver's seat. (This will pull the brake pedal off the ball head of
the push rod).
Connecting brake pedal to brake servo

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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.

4. Brake pedal and mounting bracket - exploded view 91

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

Stop -17- on brake pedal must always be fitted, otherwise there is a risk that mounting for brake light sensor
-10- can break off when brake pedal is released.

– Hold ball head of push rod in front of mounting and push brake
pedal in direction of brake servo so that the ball head audibly
locks into place.
– Install brake light sensor ⇒ page 14 .

– Protected
Installbyfootwell vent -A-B-.
copyright. Copying for private or commercial purposes, in part or in whole, is not

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– permitted
Tighten bolt securing footwell vent -A-.
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.

– Attach electrical connector to footwell vent -C-.

– Install driver's storage compartment -1 ... 3-.

4.2 Removing and installing brake pedal

(vehicles with manual gearbox)
On vehicles with manual gearbox, the mounting bracket must be
removed in order to remove the brake pedal.
– Remove mounting bracket (vehicles with manual gearbox)
⇒ page 104 .

92 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Removing brake pedal with mounting bracket removed

Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1410-

– Remove bolt -3-.

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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.

– Pull off retaining clip -1- on left side and pull out pin -5- to the
right.
– Remove brake pedal.
Installing brake pedal with mounting bracket removed

WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break off when brake pedal is re‐
leased.

4. Brake pedal and mounting bracket - exploded view 93

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
Note

Stop -17- on brake pedal must always be fitted, otherwise there is a risk that mounting for brake light sensor
-10- can break off when brake pedal is released.

– Push retaining clip (right-side) onto pin.

– Slide pin from right to left through shaft in brake pedal.

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.

94 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Secure pin with retaining clip -1- on left side.

The pin must be secured with the retaining clips on both sides.

– Fit bolt -3- and tighten.

cardiagn.com
– Install mounting bracket (vehicles with manual gearbox)
⇒ page 104 .

4.3 Removing and installing brake pedal

(vehicles with automatic gearbox)
Special tools and workshop equipment required
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Torque wrench
permitted -V.A.Gby1331-
unless authorised 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.
♦ Reversible ratchet -V.A.S 5122-
♦ Release tool -T40168- for brake light sensor.

4. Brake pedal and mounting bracket - exploded view 95

 Audi A4 2008 ➤
Brake system - Edition 11.2007

♦ Release tool -T10006-

♦ Torque wrench -V.A.G 1410-

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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.

Removing
– Remove dash panel trim on driver's side -1 ... 3-.

96 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Unplug electrical connector on footwell vent -C-.

– Remove footwell vent -A-B-.
– Remove brake light sensor ⇒ page 14 .
– Separate brake pedal from brake servo ⇒ page 89 .

WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break off when brake pedal is re‐
leased.
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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 bolt -11-.

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– Remove retaining clip -5- and pull out pin -4- towards the left.
Installing

4. Brake pedal and mounting bracket - exploded view 97

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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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.

cardiagn.com
Note

Stop -17- on brake pedal must always be fitted. Otherwise, there is a risk that mounting for brake light sensor
-10- can break off when brake pedal is released.

– Push retaining clip (left-side) -12- onto pin.

– Slide pin from left to right through shaft in brake pedal.
– Secure pin with retaining clip -5- on right side.
The pin must be secured with the retaining clips -5 and 12- on
both sides.

98 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
– Fit bolt -11- and tighten.
Attaching brake pedal to brake servo
– Hold ball head of push rod in front of mounting and push brake
pedal in direction of brake servo so that the ball head audibly
locks into place.
– Install brake light sensor ⇒ page 14 .
– Install footwell vent -A-B-.
– Tighten bolt securing footwell vent -A-.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Attach electrical connector to footwell
permitted vent by-C-.
unless authorised 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. Brake pedal and mounting bracket - exploded view 99

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Install dash panel trim on driver's side -1 ... 3-.

4.4 Removing and installing mounting for

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brake servo push rod
Special tools and workshop equipment required
♦ Release tool -T40168- for brake light sensor.
♦ Release tool -T10006-

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.

Removing

WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break off when brake pedal is re‐
leased.

100 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Remove dash panel trim on driver's side -1 ... 3-.

– Unplug electrical connector on footwell vent -C-.

cardiagn.com
– Remove footwell vent -A-B-.
– Remove brake light sensor ⇒ page 14 .
– Separate brake pedal from brake servo ⇒ page 89 .

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.

4. Brake pedal and mounting bracket - exploded view 101

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break off when brake pedal is re‐
leased.

– Using a suitable tool, pry mounting -15- for brake servo push
rod out of brake pedal.

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.

102 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
Installing
– Fit mounting for brake servo push rod together with bearing
shell into brake pedal.
The mounting must engage audibly.
Attaching brake pedal to brake servo
– Hold ball head of push rod in front of mounting and push brake
pedal in direction of brake servo so that the ball head audibly
locks into place.
– Install brake light sensor ⇒ page 14 .

4. Brake pedal and mounting bracket - exploded view 103

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Install footwell vent -A-B-.

– Tighten bolt securing footwell vent -A-.
– Attach electrical connector to footwell vent -C-.

– Install dash panel trim on driver's side -1 ... 3-.

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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.

4.5 Removing and installing mounting

bracket (vehicles with manual gearbox)
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1331-
♦ Reversible ratchet -V.A.S 5122-
♦ Release tool -T40168- for brake light sensor.

104 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

♦ Release tool -T10006-

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.

Removing

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WARNING

Line the footwell with a sufficient number of cloths to protect

against brake fluid escaping at the clutch pedal.

– Remove dash panel trim on driver's side -1 ... 3-.

4. Brake pedal and mounting bracket - exploded view 105

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Unplug electrical connector on footwell vent -C-.

– Remove footwell vent -A-B-.
– Remove brake light sensor ⇒ page 14 .
– Unplug electrical connector from accelerator pedal module.
– Separate brake pedal from brake servo ⇒ page 89 .

WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break off when brake pedal is re‐
leased.

– Remove over-centre spring -2- on clutch pedal -1- ⇒ Rep. Gr.

30 .

Note

cardiagn.com
Note correct installation position of over-centre spring for subse‐
quent re-installation.

– Pull pin -4- in clutch pedal for linkage to clutch master cylinder
out of pedal arm.

Note

Do not release catches -1 and 2- before removal.

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.
– Release clutch master cylinder using release tool -3355- .
Turn special tool clockwise -arrow-.

106 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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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 body brace.

– Remove plenum chamber partition panel ⇒ Rep. Gr. 50 .
– Remove cover -2- above brake fluid reservoir.

4. Brake pedal and mounting bracket - exploded view 107

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
The cover -2- is not fitted on all vehicles.
– Remove bolts -1- securing brake servo to mounting bracket.

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.

108 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Remove nuts -16- unless
permitted on mounting
authorised bybracket guides.
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.
– Use full range of steering column adjustment to move steering
wheel out as far as possible towards driver's seat.
– Turn steering wheel to straight ahead position. Wheels are in
straight-ahead position.

Note

Dash panel insert and steering wheel do not have to be removed

in order to remove steering column.

4. Brake pedal and mounting bracket - exploded view 109

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Remove bolt -2- for steering column at bottom.

– Remove bottom bolts -2 to 4- for steering column and mount‐

ing bracket.

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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.
– Unclip trim cover -2- from top of trim -1- for steering column
switch module (SMLS) -arrow A-.
– Detach wiring guides from steering column.

Note

Shown in illustration without steering wheel. Do not remove steer‐

ing wheel and dash panel insert.

110 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Unscrew bolts -1 and 2- for steering column from central tube,

supporting steering column by hand from below.

Note

Use ratchet with 3/8" drive (commercially available) and multi-

point bit with extension to slacken and remove bolts -1 and 2-.

– Pull out steering column from steering shaft

– Carefully put down steering column with steering wheel.
– Remove mounting bracket from vehicle.

Caution

Make sure that the clutch master cylinder is not disconnected

from the hydraulic line when taking out the mounting bracket.

The clutch master cylinder remains in the vehicle.

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Installing

WARNING

Stop on brake pedal must always be fitted. Otherwise, there is

a risk that mounting for brake light sensor can break off when
brake pedal is released.
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.
Check that the seal on the clutch master cylinder is correctly
seated before fitting the mounting bracket.
– Insert mounting bracket in guides on vehicle.
Guide clutch master cylinder through aperture in mounting brack‐
et and turn mounting bracket slightly to right so that cylinder
mounts can be guided through mounting bracket.
– Fit nuts at mounting bracket guides to hold mounting bracket
in position.

– Install and tighten bolts -1- securing brake servo to mounting

bracket.

Note

First install and tighten bolts securing brake servo to mounting

bracket.

4. Brake pedal and mounting bracket - exploded view 111

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
– Tighten nuts -16- at mounting bracket guides.
– Secure clutch master cylinder in mounting bracket using re‐
lease tool -3355- .
Turn special tool anti-clockwise -arrow B-, while at the same time
pulling master cylinder forwards -arrow-.

112 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Push pin -4- for linkage to clutch master cylinder flush into
clutch pedal.
Note correct installation position of pin. The shoulder -B- on the
pin must be aligned with the slot in the pedal arm.

– Install over-centre spring -2- on clutch pedal ⇒ Rep. Gr. 30 .

cardiagn.com
– Plug in electrical connector for accelerator pedal module.
Attaching brake pedal to brake servo
– Hold ball head of push rod in front of mounting and push brake
pedal in direction of brake servo so that the ball head audibly
locks into place.

WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break
Protected off when
by copyright. brake
Copying pedal
for private is re‐ purposes, in part or in whole, is not
or commercial
leased. 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.

– Install brake light sensor ⇒ page 14 .

– Slide steering column -1- onto steering shaft -3-.

– Fit steering column to central tube and insert bolts.

Note

Note different lengths of bolts.

4. Brake pedal and mounting bracket - exploded view 113

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Tighten bolts -1 and 2- to 20 Nm in diagonal sequence.

Note

Use ratchet with 3/8" drive (commercially available) and multi-

point bit with extension to fit bolts -1 and 2-.

– Use torque wrench -V.A.G 1331- and reversible ratchet -V.A.S

5122- with extension to tighten bolts to 20 Nm.
– Clip trim cover into top of trim for steering column switch mod‐
ule (SMLS).
– Attach wiring guides to steering column.

– Tighten bolt on steering shaft -2- to 20 Nm.

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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.

– Fit bottom bolts -1 to 4- for steering column and mounting

bracket and tighten to 20 Nm.

– Install footwell vent -A-B-.

– Tighten bolt securing footwell vent -A-.
– Attach electrical connector to footwell vent -C-.

114 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Install dash panel trim on driver's side -1 ... 3-.

– Install cover -2- above brake fluid reservoir.

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.

cardiagn.com

The cover -2- is not fitted on all vehicles.

– Install plenum chamber partition panel ⇒ Rep. Gr. 50 .

4. Brake pedal and mounting bracket - exploded view 115

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Install body brace ⇒ Rep. Gr. 40 .

4.6 Removing and installing mounting

bracket (vehicles with automatic gear‐
box)
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1331-
♦ Reversible ratchet -V.A.S 5122-
♦ Release tool -T40168- for brake light sensor.
♦ Release tool -T10006-

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Removing
– Remove dash panel trim on driver's side -1 ... 3-.

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.

116 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Unplug electrical connector on footwell vent -C-.

– Remove footwell vent -A-B-.
– Remove brake light sensor ⇒ page 14 .
– Unplug electrical connector from accelerator pedal module.
– Separate brake pedal from brake servo ⇒ page 89 .

WARNING

Stop on brake pedal must always be fitted. Otherwise, there is

a risk that mounting for brake light sensor can break off when
brake pedal is released.

– Remove body brace.

– Remove plenum chamber partition panel ⇒ Rep. Gr. 50 .
– Remove cover -2- above brake fluid reservoir.

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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 cover -2- is not fitted on all vehicles.

4. Brake pedal and mounting bracket - exploded view 117

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Remove bolts -1- securing brake servo to mounting bracket.

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– Remove nuts -16- at mounting bracket guides.

– Use full range of steering column adjustment to move steering
wheel out as far as possible towards
Protected driver's
by copyright. seat.
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
– Turn steering wheel to straight
with ahead
respect to position. Wheels
the correctness areinin
of information this document. Copyright by AUDI AG.
straight-ahead position.

118 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

Dash panel insert and steering wheel do not have to be removed

in order to remove steering column.

– Remove bolt -2- for steering column at bottom.

– Remove bottom bolts -2 to 4- for steering column and mount‐

ing bracket.

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– Unclip trim cover -2- from top of trim -1- for steering column
switch module (SMLS) -arrow A-.
– Detach wiring guides from steering column.

Note

Shown in illustration without steering wheel. Steering wheel and

dash panel insert do not have to be removed.
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.

4. Brake pedal and mounting bracket - exploded view 119

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Unscrew bolts -1 and 2- for steering column from central tube,

supporting steering column by hand from below.

Note

Use ratchet with 3/8" drive (commercially available) and multi-

point bit with extension to slacken and remove bolts -1 and 2-.

– Pull out steering column from steering shaft

– Carefully put down steering column with steering wheel.
– Remove mounting bracket from vehicle.
Installing

WARNING

Stop on brake pedal must always be fitted. Otherwise, there is

a risk that mounting for brake light sensor can break off when
brake pedal is released.

cardiagn.com
Check that seal to bulkhead is correctly seated before fitting
mounting bracket.
– Insert mounting bracket in guides on vehicle.
– Fit nuts at mounting bracket guides to hold mounting bracket
in position.

– Install and tighten bolts -1- securing brake servo to mounting

bracket.

Note

First install and tighten bolts securing brake servo to mounting

bracket.

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.

120 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
– Tighten nuts -16- at mounting bracket guides.
– Plug in electrical connector for accelerator pedal module.
Attaching brake pedal to brake servo
– Hold ball head of push rod in front of mounting and push brake
pedal in direction of brake servo so that the ball head audibly
locks into place.

WARNING

Stop on brake pedal must always be fitted, otherwise mounting

for brake light sensor can break off when brake pedal is re‐
leased.

– Install brake light sensor ⇒ page 14 .

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.

4. Brake pedal and mounting bracket - exploded view 121

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Slide steering column -1- onto steering shaft -3-.

– Fit steering column to central tube and insert bolts.

Note

Note different lengths of bolts.

– Tighten bolts -1 and 2- to 20 Nm in diagonal sequence.

Note

Use ratchet with 3/8" drive (commercially available) and multi-

point bit with extension to fit bolts -1 and 2-.

cardiagn.com
– Use torque wrench -V.A.G 1331- and reversible ratchet -V.A.S
5122- with extension to tighten bolts to 20 Nm.
– Clip trim cover into top of trim for steering column switch mod‐
ule (SMLS).
– Attach wiring guides to steering column.

– Tighten bolt on steering shaft -2- to 20 Nm.

– Fit bottom bolts -1 to 4- for steering column and mounting

bracket and tighten 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.

122 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Install footwell vent -A-B-.

– Tighten bolt securing footwell vent -A-.
– Attach electrical connector to footwell vent -C-.

– Install trim on driver's side -1 ... 3-.

– Install cover -2- above brake fluid reservoir.

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

cardiagn.com
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. Brake pedal and mounting bracket - exploded view 123

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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 cover -2- is not fitted on all vehicles.

– Install plenum chamber partition panel ⇒ Rep. Gr. 50 .
– Install body brace ⇒ Rep. Gr. 40 .

124 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

5 Electronic parking brake (EPB) - overview

1 - Parking brake switch -F321-

Switch is permanently lit for
easy identification at night
❑ Pull switch ⇒ to apply
“handbrake ”.
❑ Press switch ⇒ to re‐
lease brake; vehicle
must then be held with
footbrake
❑ Fitting location: in centre
console
❑ Removing and installing
⇒ page 20
2 - LED (light-emitting diode)
❑ Fitting location: in park‐
ing brake switch

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❑ Lights up when parking
brake is applied
❑ Indicator lamp in instru‐
ment cluster as addi‐
tional display
Indicator bar lights up red
when vehicle is retarded by
EPB at speeds above 7 km/h.
The system also sounds an au‐
dible warning tone.

3 - EPB system fault warning

lamp (yellow)
❑ In case of malfunction of
the parking brake the
yellow symbol in the in‐
strument cluster display
lights up additionally
and the warning: Park‐
ing brake! is displayed.
4 - Indicator lamp for electronic parking brake
Lamp lights up red:
❑ To indicate that required clamping force
Protected has been
by copyright. Copyingbuilt up or commercial purposes, in part or in whole, is not
for private
❑ The lamp lights up with parkingpermitted
brake applied and ignition switched on.
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 lamp stays on for approx. 20 seconds after the ignition is switched off.
❑ If the parking brake is applied with ignition switched off, the lamp lights up for approx. 20 seconds.
❑ The lamp should go out when the parking brake is released.
Lamp flashes red:
If the lamp flashes red continuously after the parking brake has been applied, this can have one of the following
causes:
♦ The braking force developed by the parking brake is not sufficient to prevent the vehicle from rolling
♦ The temperature of the brakes is too high
If the lamp flashes red, the vehicle must be held by another means

Lamp lights up green:

❑ Lamp indicates that Audi hold assist (AHA) is active

5. Electronic parking brake (EPB) - overview 125

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Yellow warning lamp lights up additionally:

❑ In case of malfunction of the parking brake the yellow symbol in the instrument cluster display lights up
additionally and the warning: Parking brake! is displayed.
5 - Actuator motor for electronic parking brake with brake caliper (right-side)
❑ Removing and installing ⇒ page 127
❑ Detaching and attaching brake caliper ⇒ page 67
6 - Control unit for electromechanical parking brake -J540-
❑ Fitting location: in rear right side panel behind side trim
❑ Removing and installing ⇒ page 126
❑ 9 Nm
7 - Actuator motor for electronic parking brake with brake caliper (left-side)
❑ Removing and installing ⇒ page 127
❑ Detaching and attaching brake caliper ⇒ page 67
8 - Acoustic signal
❑ Warning signal if Protected
parkingbybrake
copyright.isCopying
operated while
for private road speed
or commercial purposes,is
in above 7 km/h
part or in whole, is not
❑ Warning signal if a with
fault is detected in system
permitted 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.

cardiagn.com
5.1 Removing and installing control unit for
electromechanical parking brake -J540-
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1410-

Removing
– Fold out side trim in luggage compartment (rear right) ⇒ Rep.
Gr. 70 .
A control unit for trailer operation is fitted on some models. The
control unit for trailer operation and its mounting bracket must first
be removed before removing the control unit for electromechan‐
ical parking brake.
– Unscrew nuts.

126 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Slide retainer catch of electrical connection -2- forwards.

– Take out control unit for EPB -1- with electrical connection.
– Unplug electrical connection from control unit.
– Remove control unit from vehicle.
Installing

– Plug in electrical connection -2- to control unit.

– Slide retainer catch on connector to the rear so it engages.
– Install control unit.
– Fit nuts, 9 Nm.
Install control unit for trailer operation and bracket, if fitted. Brack‐
et: 3 Nm.

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– If the control unit for electromechanical parking brake has
been renewed, select the function “Replacing” for the relevant
control unit in the “Guided Fault Finding”.
Use vehicle diagnostic, testing and information system -VAS
5051B- or -5052-.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
5.2 Removing and installing actuator motor
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.
for electronic parking brake and hand‐
brake
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1331-

♦ Vehicle diagnosis and service information system -VAS 5051

B- or -VAS 5052-

5. Electronic parking brake (EPB) - overview 127

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Removing

Note

♦ Ignition off.
♦ Ignition must be switched off at least 30 sec. before unplugging
connector for actuator motor.
♦ Parking brake released
♦ Fault memory interrogated, indicated faults eliminated and
fault memory erased.

– Raise vehicle.
– Remove wheels.

Note

♦ Ignition must be switched off at least 30 sec. before unplugging

connector.

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♦ Clean whole area around connector and actuator motor/ brake
caliper.
♦ Unplug connector -1- of actuator motor.
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.

– Unscrew both securing bolts -1- on actuator motor.

– Detach actuator motor in direction of arrow.

128 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Remove seal with suitable tool.

Make sure you do not damage annular groove for seal and con‐
tact surface on actuator motor.

Note

Do not use tools with sharp edges.

– If necessary clean annular groove and contact surface. Use

only brake cleaner.
Installing
– Fit new seal.

– Turn adjusting screw -1- on brake caliper back slightly.

Note
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
This makes it easier to install theunless
permitted actuator motor.
authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

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

– Fit actuator motor.

Note

Ensure that seal is fitted correctly.

– Then turn actuator motor in such a way (item -2-) that bolt hole
-a- and thread in brake caliper housing -b- are aligned.
Make sure that the actuator motor is flush with the brake caliper
housing.

5. Electronic parking brake (EPB) - overview 129

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Fit both securing bolts (Torx 30) of actuator motor.

Important: Bolts for actuator motor must be fitted and screwed in
several turns by hand. If the thread is damaged the complete
brake caliper has to be renewed.
– Tighten bolts for actuator motor. Tightening torque: 12 Nm
– Plug in electrical connector onto actuator motor.

Note

♦ To avoid any damage to connector only fit it by hand.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Make sure that the connections on vehicle
permitted wiringbyand
unless authorised AUDIactuator
AG. AUDI AG does not guarantee or accept any liability

motor are clean and undamaged.

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

– Insert wiring to actuator motor in retainer.

– Fit wheels ⇒ Wheels and tyres; Rep. Gr. 44 .
After renewing actuator motor you must use vehicle diagnostic
tester to perform basic setting 006 in EPB function.

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– With ignition switched off, connect vehicle diagnostic, testing
and information system -VAS 5051B- or -VAS 5052- to 16-pin
diagnostic connector in vehicle.

130 Rep. Gr.46 - Brakes - mechanism

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
Note

♦ Ignition on
♦ Parking brake released
♦ Coding checked and rectified if necessary
♦ Fault memory interrogated, indicated faults eliminated and
fault memory erased.

– Select function “053 - Parking brake”.

– Select function “006 - Basic setting”.
– J540- Control unit for electromechanical parking brake
– J540- Basic setting (3 Function test: electronic parking brake
and handbrake)
– Press the green arrow button (bottom left) to exit from the
input mask.

5. Electronic parking brake (EPB) - overview 131

 Audi A4 2008 ➤
Brake system - Edition 11.2007

47 – Brakes - hydraulics
1 Leak test

Note

♦ The hydraulic brake system must be bled.

♦ Only genuine parts or components approved by Audi may be
installed within the brake system.
♦ The brake fluid must be changed if the replacement interval
specified by Audi for brake fluid is exceeded.
♦ Perform a visual inspection to check the brake system for
leaks.
♦ Repair any leaks found and remove any accumulated dirt from
the hydraulic system.

1.1 Leak test performed by operating brake

cardiagn.com
– Switch off engine.
– Press brake pedal repeatedly
Protected (“pump
by copyright. theprivate
Copying for brake servo dry”)
or commercial purposes, in part or in whole, is not
until there is no more servo assistance and the brake pedal is
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.
heavy.
– Press the brake pedal down approx. 20 mm out of the rest
position.
– Keep the force on the pedal constant for about 20 seconds.
The brake pedal travel should not become longer.
– Release brake pedal.
– Press pedal with substantial foot pressure.
– Keep the force on the pedal constant for about 20 seconds.
The brake pedal travel should not become longer.
The visual inspection of the brake system must be repeated if the
brake pedal resistance collapses during any of the tests.
If no leaks are then found during the test, the brake master cyl‐
inder probably has a leak and must be renewed.

Caution

Ensure that no brake fluid enters the brake servo when renew‐
ing the brake master cylinder.

1.2 High-pressure and low-pressure tests

Special tools and workshop equipment required

132 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

♦ Tester for brake pressure regulator -V.A.G 1310A-

Before starting:
Make sure that the brake system (master cylinder, brake hoses,
brake lines and brake calipers) works properly and is free of leaks.
High-pressure test:
– Remove bleeder screw at one of the front brake calipers. Con‐
nect tester for brake pressure regulator -V.A.G 1310A- and
bleed tester.

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– Protected
Insertbybrake pedal actuator -V.A.G 1869/2- between brake
copyright. Copying for private or commercial purposes, in part or in whole, is not

pedal and driver's seat.

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.

– Apply pressure to brake pedal until the gauge indicates a

pressure of 50 bar.
The pressure must not drop by more than 4 bar during the test
period of 45 seconds.
Renew hydraulic unit if drop in pressure exceeds the above figure.
Low-pressure test:
– Move the brake pedal actuator -V.A.G 1869/2- back until the
pressure gauge indicates a pressure of 6 bar.
– The pressure should not drop by more than 1 bar within the
test period of 3 minutes.
Renew hydraulic unit if drop in pressure exceeds the above figure.

1. Leak test 133

 Audi A4 2008 ➤
Brake system - Edition 11.2007

2 Servicing brake caliper - FN3 brakes

Note

♦ Install complete repair kit when servicing.

♦ New brake calipers are filled with brake fluid and are pre-bled.
♦ Apply thin coat of assembly paste -G 052 150 A2- to brake
cylinder, piston and seal.

1 - Protective caps
❑ Detach when removing
guide pins
❑ Re-install after fitting
guide pins
2 - Guide pin
❑ 30 Nm

cardiagn.com
❑ Renewing ⇒ page 136
3 - Bleeder valve
❑ Before screwing in,
grease thread with thin
coat of assembly paste -
G 052 150 A2- .
❑ 10 Nm
4 - Protective cap
❑ Push onto bleeder valve
5 - Brake caliper housing
6 - Retaining spring
❑ Insert with both ends in
the holes in brake cali‐
per housing

Note
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
The retaining spring must be press‐ permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

ed under the brake carrier after in‐ with respect to the correctness of information in this document. Copyright by AUDI AG.

serting into both holes. If incorrectly

installed, the wear of the outer pad
cannot be adjusted, and the pedal
travel will be increased as a result.

7 - Bearing bush
❑ Insert into brake caliper
housing
❑ Renewing ⇒ page 136
8 - Brake carrier
❑ Bolt to brake caliper housing
9 - Seal
10 - Piston
❑ Apply a thin coat of assembly paste -G 052 150 A2- to piston before inserting
❑ Diameter 57 mm

134 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

11 - Protective cap
❑ Do not damage when inserting piston

2.1 Removing and installing piston for front

brake caliper - FN-3 brakes
Special tools and workshop equipment required
♦ Assembly paste -G 052 150 A2-
♦ Removal wedge -3409-

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Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Piston resetting appliance -T10145- 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.

Removing
– Force piston out of brake caliper housing using compressed
air.

Note

Place a piece of wood in the recess to prevent damaging the pis‐

ton.

2. Servicing brake caliper - FN3 brakes 135

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Take out seal.

– To do so, use removal wedge -3409- .

Note

When removing ensure that the bore of the cylinder is not dam‐
aged.

Installing

– Insert inner seal into groove -arrow- in brake caliper.

cardiagn.com
– Push protective cap onto brake caliper housing and press it in
so that it makes contact all round.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– At this stage it should not unless
permitted be possible
authorised to remove
by AUDI theAGprotective
AG. AUDI does not guarantee or accept any liability
cap from the brake caliper housing by hand.
with respect to the correctness of information in this document. Copyright by AUDI AG.

– Apply a thin coat of assembly paste -G 052 150 A2- to piston

and seal before inserting.
– Press brake piston lightly against protective cap.
Keep the piston straight to avoid damaging the seal.
– Inflate protective cap with compressed air (maximum 3 bar).
The protective cap will then locate around the brake piston.

– Press brake piston into caliper using piston resetting appliance

-T10145- .
Keep the piston straight to avoid damaging the seal.

Note

The inner sealing lip on the protective cap will then locate in the
piston groove.

2.2 Renewing bearing bushes and guide

pins - FN-3 brakes

Note

Mark brake pads when removing them if they are to be reinstalled.

Reinstall in their original position to prevent uneven braking.

136 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Removing
– Unscrew pins -12- on brake caliper.

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

cardiagn.com
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.

– Detach brake caliper.

Do not leave brake caliper hanging from brake hose but secure it
to bodywork using a suitable cable tie or wire. Take care that
brake hose is not damaged by weight of brake components.
– Pull bearing bushes out of brake caliper.
Installing
Installation is carried out in reverse sequence.
– Use new guide pins.

2. Servicing brake caliper - FN3 brakes 137

 Audi A4 2008 ➤
Brake system - Edition 11.2007

3 Servicing brake caliper - FBC brakes

Note

♦ Install complete repair kit when servicing.

♦ Apply thin coat of assembly paste -G 052 150 A2- to brake
cylinder, piston and seal.

1 - Bolt
❑ 30 Nm
2 - Protective cap
❑ Insert in brake caliper
❑ Renewing ⇒ page 140
3 - Guide pin
❑ Slide through sleeve
❑ Renewing ⇒ page 140

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4 - Protective cap
❑ Push onto bleeder valve
5 - Bleeder valve
❑ Before screwing in,
grease thread with thin
coat of assembly paste -
G 052 150 A2- .
❑ 15 Nm
6 - Brake caliper housing
7 - Retaining spring
❑ Ensure correct installa‐
tion position
8 - Protective cap
❑ Do not damage when in‐
serting piston
❑ Grease with assembly
paste -G 052 150 A2- .
9 - Piston
❑ Apply a thin coat of as‐
sembly paste -G 052
150 A2- to piston before
inserting
❑ Diameter 57 mm
10 - Seal
❑ Grease with assembly paste -G 052 150 A2-
11 - Brake carrier
❑ Removing and installing ⇒ page 47Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
❑ The retaining pins (4x) for the brake with
pads ontothe brake carrier must NOT be slackened
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
respect the correctness of information in this document. Copyright by AUDI AG.

12 - Bolt
❑ 196 Nm

138 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

3.1 Removing and installing piston for front

brake caliper- FBC brakes
Removing
Special tools and workshop equipment required
♦ Assembly paste -G 052 150 A2-
♦ Removal wedge -3409-

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♦ Piston resetting appliance -T10145-

– Force piston out of brake caliper housing using compressed

air.

Note 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

Place a piece of wood in the recess to prevent damaging the pis‐

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

ton.

3. Servicing brake caliper - FBC brakes 139

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Take out seal.

– To do so, use removal wedge -3409- .

Note

When removing ensure that the bore of the cylinder is not dam‐
aged.

Installing
– The surface of the piston and seal should be cleaned using
only methylated spirits and then dried.
– Apply a thin coat of assembly paste -G 052 150 A2- to piston
and seal before inserting.

– Insert inner seal into groove -arrow- in brake caliper.

cardiagn.com
– Push protective cap onto brake caliper housing and press it in
so that it makes contact all round.
– At this stage it should not be possible to remove the protective
cap from the brake caliper housing by hand.
– Apply a thin coat of assembly paste -G 052 150 A2- to piston
and seal before inserting.
– Press brake piston lightly against protective cap.
Keep the piston straight to avoid damaging the seal.
– Inflate protective cap with compressed air (maximum 3 bar).
The protective cap will then locate
Protectedaround theCopying
by copyright. brake piston.
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 brake piston into caliper using piston resetting appliance

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

-T10145- .
Keep the piston straight to avoid damaging the seal.

Note

The inner sealing lip on the protective cap will then locate in the
piston groove.

3.2 Renewing protective caps and guide

pins - FBC brakes
The guide pins must be removed if the protective caps are dam‐
aged.

140 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Removing

Note

Mark brake pads when removing them if they are to be reinstalled.

Reinstall in their original position to prevent uneven braking.

– Press down centre of retaining spring -7-.

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

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

Note

♦ The spring is under tension; hold your hand over the spring to
avoid risk of injury.
♦ When removing the spring, take care not to scratch or chip the
paint on the brake caliper.

– Carefully detach retaining spring.

– Remove bolts -1- on brake caliper.
– Detach brake caliper.

3. Servicing brake caliper - FBC brakes 141

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Do not leave brake caliper hanging from brake hose but secure it
to bodywork using a suitable cable tie or wire. Take care that
brake hose is not damaged by weight of brake components.
– Pull outer part of protective cap -2- out of groove on guide pin.

– Pull guide pin -3- outwards out of protective cap.

– Pull protective cap out of brake caliper.
cardiagn.com
Installing
– Carefully push guide pin into protective cap as far as first
groove.
– Fit protective cap in brake caliper.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
The protective cap must be seated centrally in the
permitted unless brakebycaliper.
authorised 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.
– Push guide pin through protective cap.
The protective cap must now be seated in both grooves on the
guide pin.
Check that both guide pins move freely. It should be possible to
slide both guide pins in and out.
– Install brake caliper and tighten bolts -1-: 30 Nm.

142 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
– Fit retaining spring -7- on outer brake pad.
– Press down centre of retaining spring and fit centre tab of
spring in hole in brake caliper.

Note

♦ The spring is under tension; hold your hand over the spring to
avoid risk of injury.
♦ When fitting the spring, take care not to scratch or chip the
paint on the brake caliper.

The tab of the retaining spring must be seated properly in the hole
-arrow- in the brake caliper, otherwise the spring can become de‐
tached and the pad would not be secured.

3. Servicing brake caliper - FBC brakes 143

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com

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.

144 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

4 Servicing rear caliper for electronic

parking brake (EPB)

Note

♦ When carrying out repairs install all parts supplied in repair kit.
♦ Apply thin coat of assembly paste -G 052 150 A2- to brake
cylinder, piston and seal.

1 - Self-locking bolt
❑ 35 Nm
❑ Always renew
❑ Counter-hold on guide
pin when loosening and
tightening
2 - Brake caliper housing with
actuator

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3 - Bleeder valve
❑ 10 Nm
4 - Dust cap
❑ Fit onto bleeder valve
5 - Seal
❑ Removing and installing
⇒ page 146
6 - Compressor nut
❑ To operate the parking
brake
7 - Piston
❑ Removing and installing
⇒ page 146
8 - Guide pin
❑ Lubricate before instal‐
ling protective capby copyright. Copying for private or commercial purposes, in part or in whole, is not
Protected
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
❑ Replacementwith parts are
respect to the correctness of information in this document. Copyright by AUDI AG.
supplied with sufficient
grease
❑ Renewing ⇒ page 149
9 - Protective cap
❑ Fit onto brake carrier
and guide pin
❑ Renewing ⇒ page 149
10 - Brake carrier with guide pins and protective caps
❑ Replacement carriers are supplied assembled and with sufficient grease on guide pins
❑ If protective caps or guide pins are damaged, renew using repair kit. Use grease sachet supplied to
lubricate the guide pins.
11 - Protective cap
❑ Removing and installing ⇒ page 146
❑ Fit outer sealing lip onto piston

4. Servicing rear caliper for electronic parking brake (EPB) 145

 Audi A4 2008 ➤
Brake system - Edition 11.2007

4.1 Removing and installing piston for rear brake caliper

cardiagn.com
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.

Special tools and workshop equipment required

♦ Torque wrench -V.A.G 1331-
♦ Torque wrench -V.A.G 1332-
♦ Piston resetting appliance -T10145-
♦ Removal wedge -3409-
♦ Vehicle diagnostic, testing and information system -VAS
5051B-
Removing
– Screw piston out of brake caliper as far as possible.

146 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Force piston out of brake caliper housing using compressed

air.

Note

♦ When removing ensure that the bore of the cylinder is not

damaged.
♦ Place a piece of wood in the recess to prevent damaging the
piston.

– Remove the old seal from the brake caliper using removal
wedge -3409- .
Installing

cardiagn.com
– Fit the new seal in the brake caliper.

– Fit the new protective cap onto the brake piston as shown in
the illustration.
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.

4. Servicing rear caliper for electronic parking brake (EPB) 147

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Screw in compressor nut to dimension -a- 15 mm.

– Insert protective cap into groove in brake caliper. To do this

use removal wedge -3409- .
– Carefully slide brake piston into brake caliper. Turn brake pis‐
ton as required. There are only four positions in which it is
possible to guide the brake piston over the compressor nut.

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– Press brake piston onto stop in brake caliper after guiding it
onto the compressor nut.

Note

Make sure not to damage the compressor nut.

– Screw in compressor nut onto stop by turning clockwise.

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.

148 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Make sure that the protective cap fits tight all round the brake
caliper housing -arrows-.

– Press piston into brake caliper by hand.

Note

The inner sealing lip on the protective cap will then locate in the
piston groove.

cardiagn.com
4.2 Renewing protective caps and guide
pins of rear brakes
If protective caps or guide pins are damaged, renew using repair
kit. Use grease sachet supplied to lubricate guide pins.
Removing
– Remove bolts -1- on brake caliper.
– Detach brake caliper.
Do not leave brake caliper hanging from brake hose but secure it
to bodywork using a suitable cable tie or wire. Take care that
brake hose is not damaged by weight of brake components.

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.

4. Servicing rear caliper for electronic parking brake (EPB) 149

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Pull protective cap -9- out of groove in brake carrier.

– Pull guide pin -8- out of brake carrier.
– Pull protective cap off guide pin.
Installing
– Grease guide pin before installing.
– Slide protective cap over groove on guide pin.

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.

– Push guide pin -8- with protective cap -9- through brake car‐
rier.

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– Press protective cap over groove on brake carrier.
– Install brake caliper.

– Screw in and tighten bolts -1-.

150 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

5 Bleeding brake system

WARNING

♦ Do not under any circumstances allow brake fluid to come

into contact with fluids that contain mineral oils (e.g. oil,
petrol, cleaning agents). Mineral oils damage the plugs
and seals in the brake system.
♦ Brake fluid is poisonous and must NOT be sucked through
a hose with the mouth. Because of its caustic properties it
must also not come into contact with paintwork.
♦ Brake fluid is hygroscopic, i.e. it absorbs moisture from the
surrounding air, and should therefore always be stored in
airtight containers.
♦ Brake fluid flushed out during the bleeding process must
not be re-used and must be disposed of in the proper
manner.
♦ Always observe the relevant environmental regulations for
disposal ⇒ page 5 .

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Note

♦ Only use new brake fluid conforming to US standard FMVSS

116 DOT 4.
♦ Genuine VW/Audi brake fluid conforms to this specification.
♦ Do not use liquids containing silicone.
♦ Avoid contamination of brake fluid with any dirt particles or bits
of fluff (e.g. from cleaning cloths etc.).
♦ Rinse off spillages using plenty of water.
♦ When the system is open do not work with compressed air and
do not move the vehicle.
♦ During the final road test, ensure that at least one ABS-con‐
trolled braking operation is performed (pulsations must be felt
at the brake pedal).
♦ The brake system warning lamp flashes if the level of the brake
fluid is too low, in case of a malfunction of the ABS or a mal‐
function of the electronic parking brake.

5.1 Procedure for bleeding Protected

brakebysystem
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.
WARNING

To ensure that the brake system and all electronic brake con‐
trol systems function correctly and safely, it is important to
bleed the entire brake system and its hydraulic components
correctly. The hydraulic unit -N55- must be filled before the
service work is performed.

5. Bleeding brake system 151

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

♦ A pressure of at least 2 bar is required to bleed the hydraulic

unit -N55-. For this reason it is important to always check the
pressure setting on the bleeder unit.
♦ Only use the brake pedal actuator when installing brake sys‐
tem components, and bleed the system afterwards.

Special tools and workshop equipment required

♦ -VAS 5234- Brake filling and bleeding equipment
♦ -VAS 5234/1- Adapter

cardiagn.com
Bleeding brake system with brake filling and bleeding equipment
VAS 5234 and adapter VAS 5234/1
Please follow operating instructions for authorised
-VAS 5234-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
permitted unless

– Remove plenum chamber cover ⇒ Rep. Gr. 50 .

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

– Raise vehicle.
– Connect -VAS 5234- with adapter -VAS 5234/1- .
– Open bleeder screws in the specified sequence and bleed
brake system (assist as required with pedal pressure).
Bleeding sequence

WARNING

Each brake caliper has two bleeder screws. To ensure opti‐

mum bleeding of the brake system, bleed the system at each
of the two bleeder screws on the brake calipers. Always bleed
the calipers first at the outer bleeder screw then at the inner
bleeder screw.

1 - Front left-side brake caliper

2 - Front right-side brake caliper
3 - Rear left-side brake caliper
4 - Rear right-side brake caliper
– Keep bleeding the calipers until clear, foam-free brake fluid
emerges.
– Close bleeder screws.
– Lower vehicle.
– Install plenum chamber cover ⇒ Rep. Gr. 50 .

152 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

5.2 Changing brake fluid

Changing brake fluid
⇒ Maintenance ; Booklet 405 ; Work descriptions; Changing
brake fluid (every 2 years)

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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.

5. Bleeding brake system 153

 Audi A4 2008 ➤
Brake system - Edition 11.2007

6 Brake servo/ brake master cylinder -

exploded view

Note

♦ Brake master cylinders can no longer be dismantled, i.e. there

is no provision for servicing.
♦ Use only new brake fluid. Observe information on brake fluid
reservoir!

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

from brake fluid reser‐

voir
❑ Removing and installing
⇒ page 157
2 - Cover for brake fluid reser‐

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voir
❑ Not installed in all vehi‐
cles
❑ Removing and installing
⇒ page 155

Note

The cover is not fitted on all vehi‐

cles.

3 - Filler cap with seal and

warning contact for brake fluid
level --F34--
4 - Bolt
❑ 5 Nm
5 - Pipe to clutch master cylin‐
der
6 - Brake servo
❑ Adjusting ball head
⇒ page 155
❑ Function test: With the
engine turned off, firmly
depress the brake pedal
several times (this re‐
duces the vacuum
present in the servo
unit).
❑ Then hold brake pedal in applied position employing moderate force and start engine. If the servo unit
is working properly, the pedal will give slightly under foot (servo assistance becomes activated).
❑ With bonded gasket
❑ Renew complete unit if defective
❑ Removing and installing ⇒ page 162
7 - Bolt for pedal bracket
❑ 20 Nm
8 - Brake pedal
❑ Removing and installing; vehicles with manual gearbox ⇒ page 92

154 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

❑ Removing and installing; vehicles with automatic gearbox ⇒ page 95

9 - Brake light sensor
❑ Removing and installing ⇒ page 14
10 - Bolt
❑ Connects brake servo to mounting bracket
❑ 25 Nm
11 - Hexagon nut
❑ For brake master cylinder
❑ 49 Nm
12 - Brake line
❑ Brake master cylinder to hydraulic unit
❑ 16 Nm
13 - Brake line
❑ Brake master cylinder to hydraulic unit
❑ 16 Nm
14 - Seal

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❑ Renew
15 - Brake master cylinder
❑ Cannot be repaired. If faulty, renew complete.
❑ Removing and installing ⇒ page 160
16 - bySealing
Protected copyright. plug
Copying for private or commercial purposes, in part or in whole, is not

❑ Moisten with brake fluidin and press Copyright

into brake fluid
AG. reservoir
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information this document. by AUDI

Note

Use only new brake fluid. Observe information on brake fluid res‐
ervoir!

Adjusting ball head

LHD vehicles:
RHD vehicles:
-a = 164.7 mm ± 0.5 mm-

Note

♦ Surface -1- for measuring.

♦ The ball head must be set at right angles to the surface of the
brake servo when taking the measurement.
♦ Measure to end of ball head without gasket fitted.

Ball head to push rod 30 Nm

6.1 Removing and installing cover for brake

fluid reservoir
Not installed in all vehicles
The cover for the brake fluid reservoir has an aperture on the left
side for checking the brake fluid level. To avoid later damage,

6. Brake servo/ brake master cylinder - exploded view 155

 Audi A4 2008 ➤
Brake system - Edition 11.2007

make sure no brake fluid is allowed to penetrate between the

brake fluid reservoir and the cover for the brake fluid reservoir.
Removing
– Remove plenum chamber cover ⇒ Rep. Gr. 50 .
– Remove bolt -4-.

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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 cover for brake fluid reservoir from vehicle.

Installing
– Fit cover for brake fluid reservoir over brake fluid reservoir.
– Screw in and tighten bolt -4-.

156 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
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
– Install plenum chamber cover ⇒ Rep. Gr. to50
with respect the .correctness of information in this document. Copyright by AUDI AG.

6.2 Removing and installing brake fluid res‐

ervoir
Removing
– Remove plenum chamber cover ⇒ Rep. Gr. 50 .
– Unplug electrical connector for brake fluid level warning con‐
tact --F34-- .
– Remove cover for brake fluid reservoir ⇒ page 155 .
– As protection against escaping brake fluid, place a sufficient
number of lint-free cloths in area beneath brake master cylin‐
der.
– Draw off as much brake fluid as possible from brake fluid res‐
ervoir using brake filling and bleeding equipment -VAS 5234-
and adapter -VAS 5234/1- .
– On vehicles with manual gearbox, detach hydraulic line for
clutch -5- from brake fluid reservoir and seal off.

6. Brake servo/ brake master cylinder - exploded view 157

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
WARNING

♦ Do not under any circumstances allow brake fluid to come

into contact with fluids that contain mineral oils (e.g. oil,
petrol, cleaning agents). Mineral oils damage the plugs
and seals in the brake system.
♦ Brake fluid is poisonous and must NOT be sucked through
a hose with the mouth. On account of its corrosive effect
it must also not be allowed to come into contact with paint‐
work.
♦ Always observe the relevant environmental regulations for
disposal.

– Pull locking pin at bottom out of brake fluid reservoir.

– Remove brake fluid reservoir from brake master cylinder.
Installing
Do not remove dust cap from new brake fluid reservoir until res‐
ervoir is ready to be filled.
– Lubricate plugs on brake fluid reservoir with brake fluid.

158 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Insert brake fluid reservoir in sealing plugs in brake master

cylinder.
– Press locking pin at bottom through brake fluid reservoir.
– Plug in electrical connector for brake fluid level warning con‐
tact --F34-- .
– On vehicles with manual gearbox, attach hydraulic line for
clutch -5- to brake fluid reservoir.

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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.

– Fill up brake fluid as far as mark.

– Bleed brake system ⇒ page 151 .
– On vehicles with manual gearbox, bleed clutch ⇒ Rep. Gr.
30 .
– Install cover for brake fluid reservoir.

Note

The cover for the brake fluid reservoir is not fitted on all vehicles.

– Install plenum chamber cover ⇒ Rep. Gr. 50 .

6. Brake servo/ brake master cylinder - exploded view 159

 Audi A4 2008 ➤
Brake system - Edition 11.2007

6.3 Removing and installing brake master

cylinder
Removing
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1331-
♦ Adapter -VAS 5234/1-
♦ Brake filling and bleeding equipment -VAS 5234-
♦ Sealing plug repair kit, Part No. -1H0 698 311 A-
Removing
– Remove plenum chamber cover ⇒ Rep. Gr. 50 .
– Detach engine cover panel.
– Remove body brace ⇒ Rep. Gr. 40 .
– Remove plenum chamber partition panel ⇒ Rep. Gr. 50 .
– As protection against escaping brake fluid, place a sufficient
number of lint-free cloths in area beneath brake master cylin‐

cardiagn.com
der.
– Draw off as much brake fluid as possible from brake fluid res‐
ervoir using brake filling and bleeding equipment -VAS 5234- .

WARNING

♦ Do not under any circumstances allow brake fluid to come

into contact with fluids that contain mineral oils (e.g. oil,
petrol, cleaning agents). Mineral oils damage the plugs
and seals in the brake system.
♦ Brake fluid is poisonous and must NOT be sucked through
a hose with the mouth. On account of its corrosive effect
it must also not be allowed to come into contact with paint‐
work.
♦ Always observe the relevant environmental regulations for
disposal.

– Remove brake fluid reservoir ⇒ page 157 .

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.

160 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Disconnect brake lines -2- from brake master cylinder and seal
brake lines with plugs from repair kit.
– Unscrew securing nuts -3- for brake master cylinder.
– Detach brake master cylinder from brake servo.
– Remove brake master cylinder from vehicle.

Caution

Brake fluid must not be allowed to enter the brake servo.

Installing
Installation is carried out in the reverse sequence.

Caution

Brake fluid must not be allowed to enter the brake servo.

cardiagn.com
Use new nuts.
– Renew seal between brake master cylinder and brake servo.
– When fitting brake master cylinder, make sure that push rod
is correctly positioned in brake servo.
– Depress brake pedal slightly to make it easier to guide push
rod into brake master cylinder.

– Install and tighten new nuts -3-. Note tightening torque.

– Connect brake lines -2- to brake master cylinder. Note tight‐
ening torque.

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. Brake servo/ brake master cylinder - exploded view 161

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
– Install brake fluid reservoir -1- ⇒ page 157 .
– On vehicles with manual gearbox, attach hydraulic line -5- for
clutch to brake fluid reservoir.
– Fill up brake fluid as far as mark.
– Bleed brake system ⇒ page 151 .
– On vehicles with manual gearbox, bleed clutch ⇒ Rep. Gr.
30 .
– Install plenum chamber partition panel ⇒ Rep. Gr. 50 .
– Install body brace ⇒ Rep. Gr. 40 .
– Install engine cover panel.
– Install plenum chamber cover ⇒ Rep. Gr. 50 .
– Carry out ESP road test and system test.

6.4 Removing and installing brake servo

Removing
Special tools and workshop equipment required
♦ Torque wrench -V.A.G 1331-

162 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

♦ Adapter -VAS 5234/1-

♦ Brake filling and bleeding equipment -VAS 5234-
♦ Sealing plug repair kit, Part No. -1H0 698 311 A-
– Switch off engine.
– Press brake pedal repeatedly (“pump the brake servo dry”)
until there is no more servo assistance and the brake pedal is
heavy.
– Remove driver's storage compartment -1 ... 3-.

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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.

– Unplug electrical connector on footwell vent -C-.

– Remove footwell vent -A-B-.
– Remove brake light sensor ⇒ page 14 .
– Separate brake pedal from brake servo ⇒ page 89 .
– Detach engine cover panel.
– Remove plenum chamber cover ⇒ Rep. Gr. 50 .
– Remove body brace ⇒ Rep. Gr. 40 .
– Remove plenum chamber partition panel ⇒ Rep. Gr. 50 .
– Remove brake fluid reservoir ⇒ page 157 .

– Unscrew nuts -3- for brake master cylinder ⇒ page 160 .

– Remove brake master cylinder from vehicle.
– Put down brake master cylinder so that no brake fluid can es‐
cape.

6. Brake servo/ brake master cylinder - exploded view 163

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Detach vacuum line -3- from brake servo.

– Remove bolts -1- securing brake servo to mounting bracket.

– Remove brake servo from vehicle.
Installing
– Fit brake servo in vehicle.
Ensure that seal is seated correctly.

cardiagn.com
– Install and tighten bolts -1- securing brake servo to mounting
bracket.

– Push vacuum line -3- into brake servo.

– Install brake master cylinder -15- ⇒ page 160 .

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.

164 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
– Install brake fluid reservoir -1- ⇒ page 157 .
– On vehicles with manual gearbox, attach hydraulic line -5- for
clutch to brake fluid reservoir.
– Fill up brake fluid as far as mark.
– Bleed brake system ⇒ page 151 .
– On vehicles with manual gearbox, bleed clutch ⇒ Rep. Gr.
30 . 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
– Install plenum chamber partition panel ⇒ Rep. Gr. 50 . to the correctness of information in this document. Copyright by AUDI AG.
with respect

– Install body brace ⇒ Rep. Gr. 40 .

– Install engine cover panel.
– Install plenum chamber cover ⇒ Rep. Gr. 50 .
Attaching brake pedal to brake servo
– Hold ball head of push rod in front of mounting and push brake
pedal in direction of brake servo so that the ball head audibly
locks into place.
– Install brake light sensor ⇒ page 14 .

6. Brake servo/ brake master cylinder - exploded view 165

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Install footwell vent -A-B-.

– Tighten bolt securing footwell vent -A-.
– Plug in electrical connector -C-.

– Install driver's storage compartment -1 ... 3-.

cardiagn.com
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.

166 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

7 Exhauster pumps
A suitable exhauster pump is fitted on each engine version to
boost the brake servo.
♦ Removing and installing exhauster pump (2.7 ltr. TDI and 3.0
ltr. TDI diesel engine) ⇒ page 168
♦ Removing and installing exhauster pump (2.0 ltr. TDI engine)
⇒ page 170
♦ Removing and installing exhauster pump (4-cyl. turbo FSI en‐
gine) ⇒ page 172
♦ Removing and installing exhauster pump (V6 FSI engine)
⇒ page 174
♦ Removing and installing vacuum pump -V192- ⇒ page 175

7.1 Exhauster pump - exploded view

Note

cardiagn.com
Illustration shows only exhauster pump, not fitting location

1 - Bolt
❑ 9 Nm
❑ Unscrew in order to re‐
move pump

Note

2 - Exhauster pump
3 - Vacuum hose
❑ Secure with hose clips
(same as original equip‐
ment) ⇒ ETKA
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
4 - Bolt 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.
❑ 5 Nm

Note

Alternatively, secure vacuum

hose with hose clip (same as
original equipment) ⇒ ETKA

5 - O-ring
❑ Renew

Note

6 - O-ring
❑ Renew

Note

7 - O-ring
❑ Renew

7. Exhauster pumps 167

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

7.2 Removing and installing exhauster

pump (2.7 ltr. TDI and 3.0 ltr. TDI diesel
engine)
Removing
The exhauster pump is located at the rear of the right-side cylinder
bank, as seen in the direction of travel -arrow-.

cardiagn.com
– Carefully pull engine cover panel away from retaining pins,
one after the other.

Note

Due to restricted space in the engine compartment, it is recom‐

mended to remove the exhauster pump before disconnecting the
vacuum line, and to re-connect the vacuum line before installing
the pump.

– Remove plenum chamber cover ⇒ Rep. Gr. 50 .

Caution

Take care not to damage the vacuum hose. The vacuum hose
must be renewed if it is damaged.

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.

168 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Disconnect vacuum line and vacuum hose at back of plenum

chamber partition panel -2-.
– Pull vacuum line -1- out of plenum chamber partition panel
-2-.

– Remove all bolts -arrows- from sealing flange of exhauster

pump.
– Pull exhauster pump out of its mounting.
– Disconnect vacuum line from exhauster pump after removing
pump.
Installing

cardiagn.com
Note

Renew seal.

Ensure that seal is seated correctly.

– Connect vacuum line to exhauster pump before installing
pump.
Pay attention to correct installation position.
– Turn drive lugs of exhauster pump so they engage in slots in
camshaft when exhauster pump is installed.
– Fit exhauster pump in position.
– Ensure that seal is seated correctly.
– Fit all bolts to sealing flange of exhauster pump and tighten
⇒ Item 1 (page 167) .
– Fit vacuum line into plenum chamber partition panel.
– Connect vacuum line and vacuum hose at back of plenum
chamber partition panel.
– Install plenum chamber cover ⇒ Rep. Gr. 50 .
– Install engine cover panel.

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. Exhauster pumps 169

 Audi A4 2008 ➤
Brake system - Edition 11.2007

7.3 Removing and installing exhauster

pump (2.0 ltr. TDI diesel engine)
Removing
The exhauster pump is located in the rear of the engine compart‐
ment -arrow-, as seen in the direction of travel.

– Detach engine cover panel.

The plenum
permitted chamber partition
by AUDI panel
AG. AUDIdoes not
not have toorbe re‐any liability
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
unless authorised AG does guarantee accept
moved. with respect to the correctness of information in this document. Copyright by AUDI AG.

cardiagn.com
– Unbolt pressure sensor -1- for diesel particulate filter at brack‐
et.
– Unclip pressure sensor pipe -2- and carefully press to the side.
– Remove bracket for pressure sensor at exhauster pump.
– Unscrew coolant pipe at bracket and at left engine transpor‐
tation shackle and press to the side.

170 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Detach vacuum hose -1- from exhauster pump.

– Remove all four bolts -arrows- from sealing flange of exhaus‐
ter pump.
– Pull exhauster pump out of its mounting.
Installing

Note

Renew seal.

Ensure that seal is seated correctly.

– Turn drive lugs of exhauster pump so they engage in slots in
camshaft when exhauster pump is installed.
– Fit exhauster pump in position.
– Ensure that seal is seated correctly.

– Fit all four bolts -arrows- to sealing flange of exhauster pump

and tighten ⇒ Item 1 (page 167) .

cardiagn.com
– Connect vacuum hose to exhauster pump.
– Screw coolant pipe into bracket and left engine transportation
shackle.

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.

– Fit bracket for pressure sensor -1- of diesel particulate filter at

exhauster pump.
– Secure bracket.
– Clip pressure sensor pipes into bracket.
– Tighten pressure sensor.
– Install engine cover panel.

7. Exhauster pumps 171

 Audi A4 2008 ➤
Brake system - Edition 11.2007

7.4 Removing and installing exhauster

pump (4-cyl. turbo FSI engine)
Before removing the exhauster pump, the high-pressure fuel
pump must be removed ⇒ Rep. Gr. 24 .
The plenum chamber partition panel does not have to be re‐
moved.
Removing
The exhauster pump is located in the rear of the engine compart‐
ment -arrow-, as seen in the direction of travel.

WARNING

Fuel line is under pressure, do not disconnect.

cardiagn.com
– Carefully pull engine cover panels away from retaining pins,
one after the other.
The exhauster pump is located in the rear of the engine compart‐
ment on the right side, as seen in the direction of travel.
– Unplug electrical connector -1- for high-pressure fuel pump.

– Unclip electrical wire from bracket -arrow-.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Remove high-pressure fuel
permitted pump
unless -2- by⇒AUDI
authorised Rep.AG. Gr. 24does
AUDI AG . not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
– Slacken ignition coil rail at bracket.

172 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Carefully unplug connectors -arrows- for ignition coils.

– Carefully press ignition coil rail to one side.
– Unscrew lines at high-pressure pump and exhauster pump
and press to one side.
– Disconnect vacuum hose from exhauster pump at hose clip.

Caution

Take care not to damage the vacuum hose. The vacuum hose
must be renewed if it is damaged.
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 all bolts -arrows- from sealing flange of exhauster

pump.

Note

Do not disconnect vacuum hose from vacuum line at plenum

chamber partition panel -2-.

cardiagn.com
– Pull exhauster pump out of its mounting.
Installing

Note

Renew seal.

Ensure that seal is seated correctly.

– Turn drive lugs of exhauster pump so they engage in slots in
camshaft when exhauster pump is installed.
– Ensure that seal is seated correctly.

– Fit all bolts -arrows- to sealing flange of exhauster pump and

tighten ⇒ Item 1 (page 167) .
– Slide new hose clip onto vacuum hose.
– Slide vacuum hose onto connection on exhauster pump.
– Use suitable pliers to tighten hose clip on connection of ex‐
hauster pump.

Caution

Take care not to damage the vacuum hose. The vacuum hose
must be renewed if it is damaged.

– Tighten lines to high-pressure pump and exhauster pump.

7. Exhauster pumps 173

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Plug in connectors -arrows- for ignition coils.

– Secure ignition coil rail.
– Install high-pressure fuel pump ⇒ Rep. Gr. 24 .
– Install engine cover panel.

7.5 Removing and installing exhauster

pump (V6 FSI)
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
The exhauster pump is located inpermitted
the front
unlessof the engine
authorised by AUDI com‐
AG. AUDI AG does not guarantee or accept any liability
partment on the left side. with respect to the correctness of information in this document. Copyright by AUDI AG.

Removing
– Carefully pull engine cover panels away from retaining pins,

cardiagn.com
one after the other.
– Slacken hose clip on vacuum hose.

Caution

Take care not to damage the vacuum hose. The vacuum hose
must be renewed if it is damaged.

– Detach vacuum hose from vacuum pump.

– Remove all bolts from sealing flange of exhauster pump.
– Pull exhauster pump out of its mounting.
Installing

Note

Renew seal.

Ensure that seal is seated correctly.

– Turn drive lugs of exhauster pump so they engage in slots in
camshaft when exhauster pump is installed.
– Fit exhauster pump in position.
– Ensure that seal is seated correctly.
– Fit all bolts to sealing flange of exhauster pump and tighten
⇒ Item 1 (page 167) .
– Slide new hose clip onto vacuum hose.
– Slide vacuum hose onto connection on exhauster pump.
– Use suitable pliers to tighten hose clip on connection of ex‐
hauster pump.
– Carefully fit engine cover panels into retaining pins, one after
the other.

174 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

8 Vacuum pump -V192- - overview

The vacuum pump -V192- is not installed on all engine versions.
The electrical vacuum pump -V192- is switched on by the engine
control unit according to intake manifold pressure.

1 - Vacuum line
2 - Electrical connector
3 - Vacuum pump for brakes -
V192-
❑ Removing and installing
⇒ page 175
❑ Checking ⇒ page 177
4 - Non-return valve
❑ Removing and installing
❑ Checking ⇒ page 181
5 - Bracket for vacuum pump -

cardiagn.com
V 192-
❑ Removing and installing
⇒ page 176
6 - Nut for bracket
❑ 20 Nm

8.1 Removing andby copyright.

Protected installing
Copying vacuum pump
for private or commercial purposes, in part or in whole, is not
-V192- with respect to the correctness of information in this document. Copyright by AUDI AG.
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

The vacuum pump -V192- is not installed on all engine versions.

The electrical vacuum pump ( vacuum pump for brakes -V192- )
is switched on by the engine control unit according to intake mani‐
fold pressure.
The vacuum pump is not intended to be serviced. If problems oc‐
cur, trace the fault by means of a function test and/or pressurised
leak test. If a fault is found, the electric vacuum pump must be
renewed.
Removing

Note

The electrical vacuum pump is located on the right-side of the

engine compartment in front of the plenum chamber partition
panel.

– Detach engine cover panel.

8. Vacuum pump -V192- - overview 175

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Unplug electrical connector -1-.

– Release hose clip on vacuum hose using suitable pliers.
– Disconnect vacuum hose from vacuum pump.

– Press clips -arrow- on both sides out of retainers by hand.

cardiagn.com
– Lift out electrical vacuum pump, holding rubber buffer below
pump firmly.

Note

Make sure that the rubber buffer below the pump does not drop
into the engine compartment when detaching the vacuum pump
-V192-.

Installing
Installation is carried out in the reverse sequence.

Note

Use new hose clip when fitting vacuum line.

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.

8.2 Removing and installing bracket for vac‐

uum pump -V192-

Note

The vacuum pump must be detached from the bracket prior to

removing the bracket.

Removing
– Detach engine cover panel.
– Remove vacuum pump ⇒ page 175 .

176 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Remove two nuts -6- on bracket.

– Remove bracket from vehicle.
Installing
– Installation is carried out in reverse sequence.

8.3 Checking vacuum pump -V192-

Description and function
The electrical vacuum pump is switched on by the engine control
unit, depending on intake manifold pressure.
The vacuum pump is capable of self-diagnosis. Recognised faults
are stored in the engine control unit.

cardiagn.com
Note

The engine must not be running when you check the function of
the electric vacuum pump via self-diagnosis.

Special tools and workshop equipment required

♦ Vehicle diagnosis, testing and information system -VAS
5051B- or -VAS 5052-

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. Vacuum pump -V192- - overview 177

 Audi A4 2008 ➤
Brake system - Edition 11.2007

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.

cardiagn.com
Procedure
– Switch off ignition.
– Press brake pedal repeatedly (“pump the brake servo dry”)
until there is no more servo assistance and the brake pedal is
heavy.
– With ignition switched off, connect vehicle diagnostic, testing
and information system -VAS 5051B- or -VAS 5052- to 16-pin
diagnostic connector in vehicle.

178 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

cardiagn.com
– Switch on vehicle diagnosis, testing and information system .
The tester may need up to 3 minutes before it is ready for oper‐
ation.
– Switch on ignition.
– Select mode: Press the button on the display for “Vehicle self-
diagnosis”.
– Select vehicle system: Press the button for “01 - Engine elec‐
tronics”.
The control unit identification and coding will appear at the top
right of the display.
– Select diagnosis function (all diagnosis functions are available
at this stage).
– Select “006 - Basic setting” on the display.
– Press buttons 0 , 0 and 8 .
– Confirm entry with Q key.
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

The following information will appear at the bottom of the display:

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

8. Vacuum pump -V192- - overview 179

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Basic setting
Not operated
Pump off
xxx mbar
Test off
– To start the test, select “activate” on the display.
The following information will appear at the bottom of the display:
Basic setting
Not operated
Pump on
xxx mbar
Test on
Do not press the brake pedal again once the test has been acti‐
vated.
The vacuum pump for brakes -V192- supplies vacuum to the
brake servo. The diagnosis of the brake servo system runs in the

cardiagn.com
control unit at the same time.
The system passes the test if the pressure in the brake servo
reaches the shut-off threshold within the time limit set by the di‐
agnostic function.
The following information will appear at the bottom of the display:
Basic setting
Not operated
Pump off
xxx mbar
Syst. OK
– You can cancel or exit from this mode by pressing the Go
to button.

The systemProtected
fails the test if the pressure in the brake servo does
by copyright. Copying for private or commercial purposes, in part or in whole, is not
not reach the shut-off
permitted threshold
unless authorised bywithin
AUDI AG. the
AUDItime limit
AG does notset by the
guarantee or accept any liability
diagnostic function.
with respect to the correctness of information in this document. Copyright by AUDI AG.

The following information will appear at the bottom of the display:

Basic setting
Not operated
Pump off
xxx mbar
Syst.n.OK
– Follow “Guided Fault Finding” procedure using vehicle diag‐
nostic, testing and information system -VAS 5051- .
To repeat the test, switch the ignition off and then on again.

8.4 Removing and installing brake servo

pressure sensor -G294-
Removing
– Remove plenum chamber cover ⇒ Rep. Gr. 50 .

180 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

Note

The brake servo pressure sensor -G294- is located in the plenum

chamber next to the brake servo.

– Unplug electrical connector -1-.

– Pull out pressure sensor in -direction of arrow-.

Note

The pressure sensor is secured with clips.

cardiagn.com
– Release clip with a pair of pliers -1-.
– Carefully lever off brake servo pressure sensor -G294- .
Installing
Installation is carried out in the reverse sequence.

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

8.5 Removing and installing non-return

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.

valve
Removing
– Disconnect vacuum hoses on both sides of non-return valve
-4-.
– Remove non-return valve from vehicle.
Installing
– Installation is carried out in reverse sequence. Note the fol‐
lowing:
The valve should allow air to pass in the direction indicated by the
arrow.
The arrow points towards the vacuum pump.

8.6 Checking non-return valve

The valve should allow air to pass in the direction indicated by the
arrow.
Valve must remain closed in opposite direction.
Observe correct installation position.
The arrow points towards the vacuum pump.

8. Vacuum pump -V192- - overview 181

 Audi A4 2008 ➤
Brake system - Edition 11.2007

9 Brake hoses and brake lines

9.1 Routing of brake hoses/lines

Replacement brake hoses and brake lines are supplied as spare
parts ready to be installed.
Secure brake hoses and brake lines to the original mounting
points when installing.
Brake lines to hydraulic unit
– Items -1- to -4- Hexagon nuts ( -M10- and M12 for ∅ 5 mm
brake lines), tightening torque 12 Nm
– Items -5- and -6- Hexagon nuts ( -M14- for ∅ 8 mm brake
lines), tightening torque 16 Nm
Brake hose to brake caliper at front axle
– Item -1- Brake hose; make sure that locating lugs engage
properly in bracket.

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– Item -2- Retaining spring

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.

– Item -3- Brake line, 17 Nm tightening torque

– Item -1- Brake line, 17 Nm tightening torque
– Item -2- Retaining spring

– Item -3- Brake hose; make sure that locating lugs engage
properly in bracket.
Brake line routing in wheel housing at front axle
– Item -1- Brake line, 12 Nm tightening torque
– Item -2- Connection piece

182 Rep. Gr.47 - Brakes - hydraulics

 Audi A4 2008 ➤
Brake system - Edition 11.2007

– Item -3- Brake line, 12 Nm tightening torque

Brake line connection in wheel housing at front wheels

– Item -1- Brake hose bracket

– Item -2- Brake line, 12 Nm tightening torque

cardiagn.com
Routing of brake lines at rear wheels
– Item -1- Brake hose, 12 Nm tightening torque
– Item -2- Brake hose bracket; make sure that locating lugs en‐
gage in bracket.
– Item -3- Retaining spring

– Item -4- Brake line, 12 Nm tightening torque

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.

9. Brake hoses and brake lines 183