Service

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

Audi A3 2021 ➤
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.

Audi A3 China 2021 ➤

Brake System
Edition 01.2023

Service Department. Technical Information

 Service
List of Workshop Manual Repair Groups

Repair Group
00 - General, Technical Data
45 - Antilock Brake System
46 - Mechanical Components
47 - Hydraulic 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.

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 © 2023 Audi AG, Ingolstadt D4B80A22C2D

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Contents

00 - General, Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1 Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 PR Number Allocation - Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1 Safety Precautions when Working near High-Voltage Components . . . . . . . . . . . . . . . . . . 3
2.2 Safety Precautions when Working on the High-Voltage System . . . . . . . . . . . . . . . . . . . . 3
2.3 Safety Precautions when Working on Vehicles with Start/Stop System . . . . . . . . . . . . . . 4
2.4 Safety Precautions during Road Test with Testing Equipment . . . . . . . . . . . . . . . . . . . . . . 4
3 Repair Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Identification Plates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Impact Wrench, Using . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.3 Guidelines for Clean Working Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.4 General Repair Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.5 Contact Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1 Technical Data, Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5 Brake Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2 Roller Test Stand, Testing Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.3 Parking Brake, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.4 Brake Rotor, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 Electrical Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.1 Diagnostic Entries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

45 - Antilock Brake System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1 Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.1 Anti-Lock Braking System (ABS) Repair Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3 Component Location Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.1 Component Location Overview - ABS/ESP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4 Control Module and Hydraulic Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.1 Overview - Control Module and Hydraulic Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.2 ABS Control Module J104/ABS Hydraulic Unit N55, Removing and Installing . . . . . . . . . . 31
4.3 Control Module, Separating from Hydraulic Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.4 Control Module, Installing on Hydraulic Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
5.1 Overview
Protected-byFront Axle
copyright. Speed
Copying Sensor
for private . . . purposes,
or commercial . . . . . .in. part
. . or
. .in. whole,
. . . .is.not
...................... 52
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
5.2 Overview - Rear
with respect Axle
to the Speed
correctness Sensorin this
of information . . document.
. . . . . .Copyright
. . . . . by. .AUDI
. . .AG.
........................ 53
5.3 Right Front ABS Wheel Speed Sensor G45/Left Front ABS Wheel Speed Sensor G47,
Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.4 Right Rear ABS Wheel Speed Sensor G44/Left Rear ABS Wheel Speed Sensor G46,
Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.5 ABS Sensor Ring, Checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

46 - Mechanical Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
1 Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
2 Front Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.1 Overview - Front Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
2.2 Brake Pads, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
2.3 Brake Caliper, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
2.4 Brake Caliper, Replacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
2.5 Brake Carrier, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Contents i
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2.6 Brake Rotor, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

2.7 Brake Shield, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
2.8 Brake Pad Wear Indicator Wire, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . 123
3 Rear Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
3.1 Overview - Rear Brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
3.2 Brake Pads, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
3.3 Brake Caliper, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
3.4 Brake Caliper, Replacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
3.5 Brake Carrier, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
3.6 Brake Rotor, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
3.7 Brake Shield, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
4 Parking Brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
4.1 Overview - Parking Brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
4.2 Left Parking Brake Motor V282/Right Parking Brake Motor V283, Removing and Installing . 1. 50
4.3 Parking Brake, Manually Loosening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
5 Brake Pedal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
5.1 Overview - Brake Pedal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
5.2 Brake Pedal, Disconnecting from Brake Booster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
5.3 Brake Pedal, Attaching to Brake Booster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
5.4 Brake Pedal, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
5.5 Mounting Bracket, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

47 - Hydraulic Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

1 Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
2 Front Brake Caliper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
2.1 Overview - Front Brake Caliper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
2.2 Brake Caliper Piston, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
2.3 Bearing Bushing and Guide Pin, Replacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
3 Rear Brake Caliper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
3.1 Overview - Rear Brake Caliper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
3.2 Dust Cap, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
3.3 Bearing Bushing and Guide Pin, Replacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
4 Brake Booster/Brake Master Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
4.1 Overview - Brake Booster/Brake Master Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
4.2 Brake Booster, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
4.3 Brake Master Cylinder, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
4.4 Brake Fluid Reservoir, Removing and Installing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
4.5 Brake Fluid Level Warning Switch F34, Removing and Installing . . . . . . . . . . . . . . . . . . . . 205
5 Hydraulic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
5.1 Brake Fluid General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
5.2 Hydraulic System, Bleeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
5.3 Leak Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214

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

ii Contents
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

00 – General, Technical Data

1 Identification
(Edition 01.2023)
A00.5A03.95.21 -- 1/31/2023
⇒ N1.1 umber Allocation - Brakes”, page 1

1.1 PR Number Allocation - Brakes

Vehicle data label, example

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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.

The respective PR number on the vehicle data label describes

which brake system is installed in the vehicle, among other
things.
♦ Example of a vehicle data label:
A - Rear Brakes (Example)
B - Front Brakes (Example)
Vehicle data label component location. Refer to ⇒ Maintenance;
Booklet 860; General Information; Vehicle Data Label.
ELSA/Vehicle-Specific Notes

The relevant information regarding the brakes installed can also

be obtained through ELSA/vehicle-specific notes.

1. Identification 1
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Example of a display:
1KU - Rear Brakes (Example)
1LJ - Front Brakes (Example)
♦ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
♦ The tables explain the PR numbers. These are important
for the brake caliper/brake rotor and brake pad combination.
Refer to ⇒ D4 ata”, page 9 .

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 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2 Safety Precautions
⇒ P2.1 recautions when Working near High-Voltage Compo‐
nents”, page 3
⇒ P2.2 recautions when Working on the High-Voltage System”,
page 3
⇒ P2.3 recautions when Working on Vehicles with Start/Stop
System”, page 4
⇒ P2.4 recautions during Road Test with Testing Equipment”,
page 4

2.1 Safety Precautions when Working near High-Voltage Components

There is a risk of fatal injury due to high voltage
The high-voltage system is under high voltage. Electrocution by
direct contact or electric arc can cause fatal or serious bodily
injury if high-voltage components and high-voltage cables are
damaged.
– Visually inspect the high-voltage components and the high-
voltage cables.
– Never use cutting, shaping, or sharp-edged tools near high-
voltage components and high-voltage cables.
– Never weld, solder, or use thermal bonding or hot air near
high-voltage components and high-voltage cables.

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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.
2.2 Safety Precautions when Working on the High-Voltage System
High voltage is extremely dangerous.
The high-voltage system is under high voltage. Electrocution by
direct contact or electric arc can cause severe bodily injury or
fatal injury.
– When working on the high-voltage system, the high-voltage
system must be de-energized.
– In some cases the high-voltage system must also be de-
energized when the work procedures do not directly affect
the high-voltage system.
– Note the work procedures that require the system to be de-
energized. Refer to ⇒ Rep. Gr. 00; High-Voltage System
Danger Classification.
– Have an Audi high-voltage technician (HVT) or an Audi high-
voltage expert (HVE) de-energize the high-voltage system.

There is a risk of fatal injury due to electric and magnetic fields

The high-voltage system emits electric and magnetic fields. Fa‐
tal or serious bodily injuries are possible if active implants (such
as pacemakers or insulin pumps) malfunction.
– Individuals with active implants must not perform any work
on high-voltage systems.

2. Safety Precautions 3
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

There is a risk of damaging the high-voltage cables.

Incorrect handling can damage the insulation on high-voltage
cables or high-voltage connectors.
– Never use the high-voltage cables and the high-voltage con‐
nectors for support.
– Never support tools on the high-voltage cables and the high-
voltage connectors.
– Never sharply bend or kink the high-voltage cables.
– Pay attention to the coding when connecting the high-volt‐
age connectors.

There is a risk of injury due to the engine starting unexpectedly.

Active drive ready mode is difficult to identify in electric and
hybrid vehicles. Parts of the body can be pinched or pulled in.
– Switch off the ignition.
– Place the ignition key outside of the vehicle interior.

There is a risk of injury due to an activated parking heater and

A/C.
The parking heater and A/C can switch on unintentionally on
electric and hybrid vehicles with an activated parking heater
and A/C. Body parts can be pinched or pulled in if the radiator
fan starts running by itself.
– Deactivate the parking heater and A/C.

2.3 Safety Precautions when Working on Vehicles with Start/Stop System

There is a risk of injury due to the engine starting unexpectedly.
The engine may start unexpectedly in vehicles with the Start/
Stop System activated. A message in the instrument cluster
indicates whether the Start/Stop System is activated.
– Deactivate the Start/Stop System: switch off the ignition.
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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.

2.4 Safety Precautions during Road Test with Testing Equipment

There is a risk of injury due to unsecured testing equipment.
If the front passenger airbag activates during a collision, unse‐
cured testing equipment becomes a dangerous projectile.
– Secure testing equipment on the rear seat.

4 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

or
– Have a second person operate testing equipment on the
rear seat.

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. Safety Precautions 5
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

3 Repair Information
⇒ P3.1 lates”, page 6
⇒ W3.2 rench, Using”, page 6
⇒ f3.3 or Clean Working Conditions”, page 6
⇒ R3.4 epair Information”, page 7
⇒ C3.5 orrosion”, page 7

3.1 Identification Plates

When replacing vehicle components, the existing identification
plates on the old parts that indicate the replacement part num‐
ber (refer to ⇒ Electronic Parts Catalog (ETKA)), must be ap‐
plied to the new part according to the specifications.

3.2 Impact Wrench, Using

Removing bolts and nuts using an impact wrench is generally
permitted. The exception to this are procedures within an open
high-voltage battery. Generally no impact wrench is permitted
for these procedures.
If the following requirements are met, using an impact wrench
to tighten bolts and nuts is permitted during repair procedures.
Electric and compressed air impact wrenches are generally in‐
tended here.
Requirements:
• Bolts with locking fluid or self-locking nuts must only be
screwed in at low speeds.
• Use a suitable impact wrench with an adjustable speed and
torque range.
• Use suitable screwdriver bits near delicate surfaces. For ex‐
ample, use plastic-coated bits on aluminum rims.
• Refer to the Natural Gas Fuel Systems - General Information
repair manual when working in a natural gas fuel system
area.
Application:
• Position the bolts or nuts by hand.
• Only tighten the bolts or nuts with an impact wrench until the
head of the bolt or nut contacts the surface and then tighten
further using a torque wrench.
• Clean the threaded pins before removing the bolt or nut.

3.3 Guidelines for Clean Working Condi‐

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tions 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 highest level of cleanliness is required when working on

the brake system. Using any products which contain mineral
oil such as oils, greases etc. is strictly prohibited.

6 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Thoroughly clean all connection points and their surrounding

areas before loosening. However, do not use aggressive
cleaning agents such as brake cleaner, gasoline, thinners or
similar compounds.
♦ Place the removed parts on a clean surface and cover them.
♦ Carefully cover or seal opened components if the repair is
not performed immediately. (Use the plugs from the Repair
Kit -1H0 698 311 A- or the Assembly Part Set -5Q0 698
311-).
♦ Only use lint-free cloths
♦ Remove the replacement parts from their packaging just pri‐
or to installing them.
♦ Only use parts in their original packaging.
♦ If the system is open, do not work with compressed air and
do not move the vehicle.
♦ Make sure that brake fluid cannot get into the connectors.

3.4 General Repair Information

♦ Clean the bolts and nuts before reusing.

♦ Always replace damaged nuts and bolts.

♦ Always replace self-locking nuts and bolts.
♦ Do not damage or bend the vacuum lines.
♦ A damaged vacuum line must be replaced.

NOTICE
Risk of destroying the brake lines by bending.
– Never change the shape of the brake lines.

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Rinse off any leaking brake fluid immediately using plenty
of water.

3.5 Contact Corrosion

Contact corrosion can
AUDIoccur if incorrect fasteners (bolts, nuts,
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AG. AUDI AG does not guarantee or accept any liability
washers,
with respect toetc.) are used.
the correctness of information in this document. Copyright by AUDI AG.

For this reason, only fasteners with a special surface coating

may be installed.

3. Repair Information 7
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Furthermore, only rubber/plastic parts and adhesive made of

electrically non-conductive materials are used.
If there are doubts about whether parts can be used or not, then
use new parts. Refer to the ⇒ Electronic Parts Catalog (ETKA).
Note:
♦ The use of Audi original replacement parts is recommended,
since they are tested and approved.
♦ The use of Audi original accessories is recommended.

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.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

4 Technical Data
⇒ D4.1 ata, Brakes”, page 9

4.1 Technical Data, Brakes

Brake system
Components Version
Brake circuit distribution Dual-circuit brake system with diagonal distribution:
♦ Left front wheel and right rear wheel
♦ Right front wheel and left rear wheel

Brake Master Cylinder Tandem brake master cylinder

Brake booster Electromechanical brake booster
Brake pressure regulation Via ABS Control Module -J104-

Steel front brakes

PR Number 1ZE 1ZD 1ZU
Brake Caliper
Brake Caliper Piston 1 1 1
Brake Rotor diame‐ 288 306 312
ter in
mm
New thickness mm 25 26 25
Wear limit mm 23. Refer to , 1),
24. Refer to1),
23. Refer to 1), ,
and Refer to ⇒ and Refer to ⇒ and Refer to ⇒
R5.4.1 otor, Check‐ R5.4.1 otor, Check‐ R5.4.1 otor, Check‐
ing, Steel Brakes”, ing, Steel Brakes”, ing, Steel Brakes”,
page 13 page 13 . page 13
Brake Pads
Wear limit Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900;
Maintenance Procedures; Brake Pad Thickness, Checking.

PR Number 1ZK, 1ZL 1LC, 1LG, 1LJ 1LY, 1LZ

Brake Caliper
Brake Caliper Piston 1 1 2
Brake Rotor diame‐ 312 340 357
ter in
mm
New thickness mm 25 30 34
Wear limit mm 23. Refer to , 1),
28. Refer to1),
32. Refer to 1),
and Refer to ⇒ and Refer to ⇒ and Refer to ⇒
R5.4.1 otor, Check‐ R5.4.1 otor, Check‐ R5.4.1 otor, Check‐
ing, Steel Brakes”, ing, Steel Brakes”, ing, Steel Brakes”,
page 13 page 13 . page 13 .
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Brake
permitted unlessPads
authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Wear limit Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
with respect to the correctness of information in this document. Copyright by AUDI AG.

Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900;

Maintenance Procedures; Brake Pad Thickness, Checking.

4. Technical Data 9
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

PR Number 1LF, 1LH

Brake Caliper
Brake Caliper Piston 6
Brake Rotor diame‐ 374
ter in
mm
New thickness mm 36
Wear limit mm 34. Refer to 1),
and Refer to ⇒
R5.4.1 otor, Check‐
ing, Steel Brakes”,
page 13 .
Brake Pads
Wear limit Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900;
Maintenance Procedures; Brake Pad Thickness, Checking.

1) The wear limit is specified on the brake rotor.

Ceramic front brakes

PR Number 1LL, 1LN, 1LU
Brake Caliper Six-Piston Brake
Brake Caliper Piston 6
Brake Rotor Diame‐ 380
ter in
mm
New thickness mm 38. Refer to 2).
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Wear limit mmunless authorised
permitted ReferbytoAUDI⇒ R5.4.2
AG. AUDI AGotors, Checking,
does not guarantee orCeramic Brakes”,
accept any liability page 16
Brake Pads
with respect to the correctness of information in this document. Copyright by AUDI AG.

Wear limit Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;

Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900;
Maintenance Procedures; Brake Pad Thickness, Checking.

2) The wear limit is specified on the brake rotor.

Refer to ⇒ B2 rakes”, page 61

Rear Brakes
PR Number 1KE, 2EC, 2EJ 1KD, 1KF, 1KI, 1KJ,
1KK, 1KY
Brake Caliper
Brake Caliper Piston 1 1
Brake Rotor diame‐ 272 310
ter in
mm
New thickness mm 10 22
Wear limit mm 8. Refer to 3)
20. Refer to 3)
and Refer to ⇒ and Refer to ⇒
R5.4.1 otor, Check‐ R5.4.1 otor, Check‐
ing, Steel Brakes”, ing, Steel Brakes”,
page 13 page 13 .
Brake Pads

10 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

PR Number 1KE, 2EC, 2EJ 1KD, 1KF, 1KI, 1KJ,

1KK, 1KY
Wear limit Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900;
Maintenance Procedures; Brake Pad Thickness, Checking.

3) The wear limit is specified on the brake rotor.

Refer to ⇒ B3 rakes”, page 127

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. Technical Data 11
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

5 Brake Inspection
⇒ I5.1 nformation”, page 12
⇒ T5.2 est Stand, Testing Vehicles”, page 12
⇒ B5.3 rake, Checking”, page 13
⇒ R5.4 otor, Checking”, page 13

5.1 General Information

The brake system is divided diagonally. The brake boosting is
performed by an electromechanical brake booster.
♦ The operation takes place on a test stand.
♦ On vehicles with manual transmission select neutral.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ On vehicles with automatic or dual clutch
permitted unless transmission
authorised by AUDI AG.select
AUDI AG does not guarantee or accept any liability
the “N” gear. with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Always follow the instructions from the test stand manufac‐

turer.
♦ Brake control systems are inoperative when the »ignition is
switched off«.

5.2 Roller Test Stand, Testing Vehicles

⇒ V5.2.1 ehicles, Checking”, page 12
⇒ V5.2.2 ehicles, Checking”, page 12

5.2.1 FWD Vehicles, Checking

Pay attention to the instructions on the test stand screen.
♦ The brake inspection must be preformed on a one-axle roller
test stand.
♦ The test speed must not exceed 6 km/h (3.7 mph), otherwise
the brakes may lock up due to the roller start-up delay (EDL
regulation).
♦ Test stands approved by Audi meet these requirements.

5.2.2 AWD Vehicles, Checking

Pay attention to the instructions on the test stand screen.
♦ With AWD, Testing with a Controlled Opposite-Running
One-Axle Roller Test Stand
♦ “Opposite-running” means: the rollers on the one-axle roller
test stand are rotated forward on one side and backward on
the other side. During this test, the wheels of one axle are
driven in opposite directions, to prevent delivering power to
the other axle.
♦ “Regulated” means: the speed of the test stand rollers must
be regulated in such a way as to avoid any speed difference
during the brake inspection. The transferring of a force to the
rolling wheels in the roller set is prevented by the stationary
wheel (outside of the roller set) via the drivetrain.
♦ During testing, the wheel turning forward is measured, there‐
fore two braking tests are necessary on each axle.
♦ The test speed must not exceed 6 km/h (3.7 mph), otherwise
the brakes may lock up due to the roller start-up delay (EDL
regulation).
♦ Test stands approved by Audi meet these requirements.

12 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

5.3 Parking Brake, Checking

Pay attention to the instructions on the test stand screen.
Activating »TÜV mode«:
• The seat belt is buckled.
• Rear axle in the one-axle roller test stand
• The engine is off and the ignition is on.
• Auto Hold is off.
• The front wheels must be stationary.
• The rear wheels must rotate for at least five seconds non-
stop between 2.5 and 9 km/h (1.6 and 5.6 mph)
»TÜV mode« is indicated when the yellow electro-mechanical
parking brake symbol with a line through it appears in the in‐
strument cluster. Refer to ⇒ Owner's Manual; Instruments and
Indicator Lamps.
♦ The electromechanical parking brake does not lock all the
way in the »TÜV mode« immediately.
♦ Operating the Electro-Mechanical Parking Brake Button -
E538- three to four times increases the tension in stages.
♦ Operating the Electromechanical Parking Brake Button -
E538- a fifth time loosens the electromechanical parking
brake.
– Start the engine.
Ending »TÜV mode«:
• Front wheels, speed greater than 0 km/h (0 mph)
• Rear wheels, speed less than 2.5 km/h (1.6 mph) or greater
than 9 km/h (5.6 mph)
• Ignition off.
Pay attention to the additional instructions on the test stand
screen.

5.4 Brake Rotor, Checking

⇒ R5.4.1 otor, Checking, Steel Brakes”, page 13
⇒ R5.4.2 otors, Checking, Ceramic Brakes”, page 16

5.4.1 Brake Rotor, Checking, Steel Brakes

Special tools and workshop equipment required
♦ Digital Dial Gauge -VAS 6668/1- or Brake Disc Vernier
Gauge -VAS 6343-, not illustrated.

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. Brake Inspection 13
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Dial Indicator - 0-10mm -VAS 6079-

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.

♦ Dial Indicator Bracket -VAS 6079/1-, not illustrated

• Respective wheel is removed. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.

Cracks, Evaluating
♦ Hairline cracks on the brake rotor friction surface are often
noticed during brake repairs. Hairline cracks up to 10 mm
long are not a technical flaw and do not justify a brake rotor
replacement.
♦ Brake rotors and brake pads that have a worn through fric‐
tion surface should be replaced.
Wear, Measuring
Due to varying contact pressures of the brake pistons to the
brake pad there are different wear areas on the friction surface.
– Brake rotor in the center wear area = measure the highest
wear level
– With Dial Gauge -VAS 6668/1- or Brake Disc Vernier Gauge
-VAS 6343- at, at least, the different locations -1-, -2- and -3-
by -a- = 120° apart from each other.

• If a measured value is below the wear value specified on

the brake rotor: replace the brake rotors on both sides of the
axle.
Brake Rotor Lateral Run-Out, Measuring
– Only perform the measurement of the brake rotor lateral
run-out, if the following conditions are met:
• There are vibrations when braking.
• Brake rotors are without scoring, hotspots, burn marks and
blue discoloration.
• Wheels and tires are OK and balanced.

14 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Tighten the brake rotor to the wheel hub using five wheel
bolts placed underneath or five other bolts that are suita‐
ble. For the tightening specification, refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
• The completely installed bolts must not touch the wheel
bearing housing behind!
– Clean dirt and rust off the brake rotor.
– Mount the Dial Indicator Bracket -VAS 6079/1- -item 2- at a
suitable location on the wheel bearing housing.

– Mount the Dial Indicator - 0-10mm -VAS 6079- -item 1- with

slight pretension and measure the lateral run-out at the di‐
mension -a- from the outer edge of the brake rotor.
• Dimension -a- = 10 mm
– When measuring, slowly turn the brake rotor via the threa‐
ded connection on the drive axle outer joint either by hand or
using a hand ratchet.
• If the lateral run-out of the brake rotor is less than 0.06 mm:
the brake rotor is OK.
• If the lateral run-out of the brake rotor is greater than 0.06
mm: measure the lateral run-out of the wheel hub.
Wheel Hub Lateral Run-Out, Measuring

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Remove either permitted
the front brake
unless rotor
authorised (refer
by AUDI AG.to ⇒ AG
AUDI R2.6.1
does nototor,
guarantee or accept any liability
Removing and Installing, Steel Brakes”, page 120 ) or the
with respect to the correctness of information in this document. Copyright by AUDI AG.

rear brake rotor (refer to ⇒ R3.6 otor, Removing and Instal‐

ling”, page 146 ).
– Mount the Dial Indicator Bracket -VAS 6079/1- at a suitable
location on the wheel bearing housing.
– Mount the Dial Indicator - 0-10mm -VAS 6079- with slight
pretension and measure the lateral run-out at the dimension
-a- under the holes for the wheel hub.

5. Brake Inspection 15
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• Dimension -a- = 5 mm
– When measuring, slowly turn the wheel hub via the threaded
connection on the drive axle outer joint either by hand or
using a hand ratchet.
• If the lateral run-out of the wheel hub is greater than 0.02
mm: replace the wheel hub.
• If the lateral run-out of the wheel hub is less than 0.02 mm:
replace the brake rotor.

5.4.2 Brake Rotors, Checking, Ceramic

Brakes
Special tools and workshop equipment required
♦ Carbon-Ceramic Brake Wear Tester -VAS 6813-, not illustra‐
ted
♦ Dial Indicator - 0-10mm -VAS 6079-

♦ Dial Indicator Bracket -VAS 6079/1-, not illustrated

Cracks

– Check the friction surface of the ceramic brake rotor:

♦ The friction surface on a new ceramic brake rotor already
has stress cracks which occur during the production proc‐
ess. These stress cracks are all different.
♦ Stress relief cracks do not mean the ceramic brake rotor is
faulty.
♦ The stress cracks are somewhat visible and can be different
from each other in strength.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Wear, Measuring 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 a quick measurement: respective wheel installed or re‐
moved, brake caliper installed.

16 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• For an exact measurement: respective wheel is removed,

brake caliper is detached and placed at least 50mm away
from the brake rotor.
• Brake rotor temperature during the test procedure is be‐
tween 0 and 40° C.
Tip
Attention, when doing the quick measurement: the metal shield
lowers the measured value.
– Check and calibrate the Carbon-Ceramic Brake Wear Tester
- VAS 6813-, if necessary refer to ⇒ Operating Instructions.
The measurement device measures the damage to the carbon
fiber reinforced material of the brake rotor. Due to temperature
effects, carbon fibers of the inner structure of the brake rotor are
damaged increasingly and the wear value lowers.
– Measure the brake rotor at three locations -B-, 120° apart
from each other, shown for measuring point “3” as an exam‐
ple.

– Position the Carbon-Ceramic Brake Wear Tester -VAS

6813- -2- with the roll-stops and the bottom, flat to the meas‐
uring point “1” of the brake rotor -1- -arrows-.

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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.

– Move the Carbon-Ceramic Brake Wear Tester -VAS 6813-

along the outer edge -2- of the brake rotor until the laser
beam points precisely at the -D- marking on the brake rotor.

5. Brake Inspection 17
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Read the measured value and note it down.

– Repeat the measurement at the measuring points “2” and

“3”.
– Compare the measured values with the wear value -C-
shown here as an example.
• If a measured value is below the wear value -C- specified on
the brake rotor: replace the brake rotor.
Chips/Broken-Off Pieces, Evaluating

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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.

– Check the friction surface on the ceramic brake rotor for any
chipping and/or broken-off pieces.
• Multiple chips/broken-off pieces -arrow- on a friction surface
are permitted.
• If there are any individual chips/broken-off pieces -arrow-
larger than 1 cm2, replace the brake pad.

18 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Edge Damage, Evaluating

– Check the ceramic brake rotor for damage to the edges.

♦ Maximum permitted width/depth = 2 mm.
♦ Maximum permitted length = 10 mm.
♦ Maximum three edge damages.
Surface Changes
– Check the friction surface of the ceramic brake rotor for top‐
ping application.
• If a pad transfer layer is determined, then check the follow‐
ing:
– Check the air routing to the brake rotor for completeness,
correct securing and damage.
– Check the brake pad quality.
– Check the perforation holes for debris.
• Clean the holes with a high pressure cleaner. Pay attention
to the environmental and safety precautions.
• Never work on the holes mechanically.
Brake Rotor Lateral
Protected Run-Out,
by copyright. Measuring
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
– Only perform the
with respect measurement
to the of thein brake
correctness of information rotorCopyright
this document. lateralby AUDI AG.
run-out, if the following conditions are met:
• There are vibrations when braking.
• Brake rotors are without scoring, hotspots, burn marks and
blue discoloration.
• Wheels and tires are OK and balanced.
– Tighten the brake rotor to the wheel hub using five wheel
bolts placed underneath or five other bolts that are suita‐
ble. For the tightening specification, refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
• The completely installed bolts must not touch the wheel
bearing housing behind!
– Clean dirt and rust off the brake rotor.
– Mount the Dial Indicator Bracket -VAS 6079/1- -item 2- at a
suitable location on the wheel bearing housing.

5. Brake Inspection 19
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Mount the Dial Indicator - 0-10mm

Protected by copyright.-VAS
Copying6079- -item
for private 1- withpurposes, in part or in whole, is not
or commercial
slight pretension andpermitted
measure unlessthe lateral
authorised run-out
by AUDI at the
AG. AUDI di‐ not guarantee or accept any liability
AG does
mension -a- from the outer edge
with respect ofcorrectness
to the the brake rotor. in this document. Copyright by AUDI AG.
of information

• Dimension -a- = 10 mm
– When measuring, slowly turn the brake rotor via the threa‐
ded connection on the drive axle outer joint either by hand or
using a hand ratchet.
• If the lateral run-out of the brake rotor is less than 0.06 mm:
the brake rotor is OK.
• If the lateral run-out of the brake rotor is greater than 0.06
mm: measure the lateral run-out of the wheel hub.
Wheel Hub Lateral Run-Out, Measuring

– Remove the brake rotor. Refer to ⇒ R2.6.2 otor, Removing

and Installing, Ceramic Brakes”, page 121 .
– Mount the Dial Indicator Bracket -VAS 6079/1- -item 2- at a
suitable location on the wheel bearing housing.
– Mount the Dial Indicator - 0-10mm -VAS 6079- -item 1- with
slight pretension and measure the lateral run-out at the di‐
mension -a- under the holes for the wheel hub.
• Dimension -a- = 5 mm
– When measuring, slowly turn the wheel hub via the threaded
connection on the drive axle outer joint either by hand or
using a hand ratchet.
• If the lateral run-out of the wheel hub is greater than 0.02
mm: replace the wheel hub.
• If the lateral run-out of the wheel hub is less than 0.02 mm:
replace the brake rotor.

20 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

6 Electrical Components
⇒ E6.1 ntries”, page 21

6.1 Diagnostic Entries

♦ 1. ABS Control Module -J104-, replacing
♦ 2. Hydraulic Unit, Removing and Installing
♦ 3. Rear Brakes Brake Pads, Removing
♦ 4. Left Parking Brake Motor -V282-/Right Parking Brake Mo‐
tor -V283-, Removing and Installing
♦ 5. Brake Booster, Removing and Installing
♦ 6. Brake Booster, Replacing
♦ 7. Hydraulic system, bleeding, when bleeding conventionally
is not OK or when a brake line from the brake master cylin‐
der to the hydraulic control unit is replaced
♦ 8. Hydraulic system, bleeding after removing and installing
the brake booster
1. ABS Control Module -J104-, replacing
♦ 0001 - Diagnostic-Capable System
♦ 0003 - Brake electronics -J104
♦ 0003 - Brake electronics, functions
♦ 0003 - Control module, replacing
2. Hydraulic Unit, Removing and Installing
♦ 0001 - Diagnostic-Capable System
♦ 0003 - Brake electronics -J104
♦ 0003 - Brake electronics, functions
♦ 0003 - output diagnostic test mode
♦ 0003 - Hydraulic valve interchange test
3. Rear Brakes Brake Pads, Removing
♦ 0001 - Diagnostic-Capable System
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
♦ 0003 - Brake electronics
with -J104
respect to the correctness of information in this document. Copyright by AUDI AG.

♦ 0003 - Brake electronics, functions

♦ 0003 - Removing brake pads
4. Left Parking Brake Motor -V282-/Right Parking Brake Motor
-V283-, Removing and Installing
♦ 0001 - Diagnostic-Capable System
♦ 0003 - Brake electronics -J104
♦ 0003 - Brake electronics, functions
♦ 0003 - Basic setting
♦ 0003 - Integrated Parking Brake, Basic Setting -J540
5. Brake Booster, Removing and Installing
♦ 0001 - Diagnostic-Capable System
♦ 0023 - Brake booster -J539
♦ 0023 - Brake booster, functions

6. Electrical Components 21
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ 0023 - Basic Settings

♦ 0023 - Brake Booster Basic Setting
6. Brake Booster, Replacing
♦ 0001 - Diagnostic-Capable System
♦ 0023 - Brake booster -J539
♦ 0023 - Brake booster, functions
♦ 0023 - Control module, replacing
7. Hydraulic system, bleeding, when bleeding conventionally is
not OK or when a brake line from the brake master cylinder to
the hydraulic control unit is replaced
♦ 0001 - Diagnostic-Capable System
♦ 0003 - Brake electronics -J104
♦ 0003 - Brake electronics, functions
♦ 0003 - Basic settings
♦ 0003 - Basic setting, brake bleeding
8. Hydraulic system, bleeding after removing and installing the
brake booster
♦ 0001 - Diagnostic-Capable System
♦ 0023 - Brake booster -J539
♦ 0023 - Brake booster, functions
♦ 0023 - Basic Settings
♦ 0023 - Brake bleeding basic setting

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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.

22 Rep. Gr.00 - General, Technical Data

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

45 – Antilock Brake System

1 Safety Precautions
Observe the safety instructions. Refer to ⇒ P2 recautions”, page
3.

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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.

1. Safety Precautions 23
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2 General Information
⇒ B2.1 raking System (ABS) Repair Information”, page 24

2.1 Anti-Lock Braking System (ABS) Re‐

pair Information
♦ ABS malfunctions do not affect the brake system and the
booster. The conventional brake system remains operative
even without ABS. A change in braking behavior must be
anticipated. When the ABS indicator lamp comes on the rear
wheels can lock-up early when braking!
♦ The ABS is generally maintenance-free.
♦ Testing, assembly, and repair work may only be performed
by qualified personnel.
♦ By not observing the points described in the repair manual,
the system can be damaged and vehicle safety could be
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
compromised. with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Before servicing the ABS, determine the cause of the dam‐

age using OBD.
♦ Disconnect the battery ground cable when the ignition is
switched off.
♦ When handling brake fluid, observe the relevant safety pre‐
cautions and notes. Refer to ⇒ F5.1 luid General Informa‐
tion”, page 207 .
♦ Bleed the brake system using the Bleeding Equipment -VAS
6860- or Brake Charger/Bleeder Unit -VAS 5234- for all work
that requires opening the hydraulic system. High and low
pressure testing should also be performed on the brake sys‐
tem.
♦ During the final road test, make sure that an ABS-controlled
brake test is performed at least once (pulsation must be felt
at the brake pedal).

24 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

3 Component Location Overview

⇒ L3.1 ocation Overview - ABS/ESP”, page 25

3.1 Component Location Overview - ABS/ESP

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. Component Location Overview 25

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Pad Wear Sensor

♦ Right Front Brake Pad
Wear Sensor -G35-
♦ Left Front Brake Pad Wear
Sensor -G34- (depending
on the model)
♦ Left Rear Brake Pad Wear
Sensor -G36- (installed
depending on the model)
2 - ABS Hydraulic Unit -N55-
❑ Component location: in
the right rear engine
compartment
❑ with
♦ Brake Pressure Sensor 1
-G201-
♦ ABS Hydraulic Pump -
V64-
♦ Valve block with intake
and exhaust valve
❑ The components can‐
not be replaced sepa‐
rately. 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
❑ Refer to ⇒ -4.1 Control with respect to the correctness of information in this document. Copyright by AUDI AG.
Module and Hydraulic
Unit”, page 28
3 - ABS Control Module -
J104-
❑ Component location: in
the right rear engine
compartment
❑ with
• Transverse Acceleration
Sensor -G200-
• Rotation Rate Sensor -G202-
• Longitudinal Acceleration Sensor -G251-
• Electromechanical Parking Brake Control Module -J540-
❑ The components cannot be replaced separately.
❑ Refer to ⇒ -4.1 Control Module and Hydraulic Unit”, page 28
4 - ASR/ESP Button -E256-
❑ In the Control Unit 1 for Driving and Convenience Functions -E791-
❑ Removing and Installing. Refer to ⇒ Electrical Equipment; Rep. Gr. 96; Controls; Component Location
Overview - Center Console Controls.
5 - Parking Brake Button -EX12-
❑ with
♦ Electromechanical Parking Brake Button -E538-
♦ Electromechanical Parking Brake Indicator Lamp -K213-
❑ Removing and Installing. Refer to ⇒ Electrical Equipment; Rep. Gr. 96; Controls; Component Location
Overview - Center Console Controls.
6 - Rear Speed Sensor
♦ Right Rear ABS Wheel Speed Sensor -G44-

26 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Left Rear ABS Wheel Speed Sensor -G46-

❑ Check using the ⇒ Vehicle diagnostic tester.
❑ Refer to ⇒ -5.2 Rear Axle Speed Sensor”, page 53
7 - Instrument Cluster -KX2-
❑ with
♦ ABS Indicator Lamp -K47-
♦ Brake System Indicator Lamp -K118-
♦ Parking Brake Indicator Lamp -K139-
❑ The indicator lamps cannot be replaced separately
❑ Refer to ⇒ Electrical Equipment; Rep. Gr. 90; Instrument Cluster; Overview - Instrument Cluster.
8 - Brake Booster -NX6-
❑ with
♦ Brake Pedal Position Sensor -G100-
♦ Brake Pedal Position Sensor 2 -G836-
❑ Refer to ⇒ -4.1 Brake Booster/Brake Master Cylinder”, page 188
9 - Front Speed Sensor
♦ Right Front ABS Wheel Speed Sensor -G45-
♦ Left Front ABS Wheel Speed SensorProtected
-G47- by copyright. Copying for private or commercial purposes, in part or in whole, is not
❑ Check using the ⇒ Vehicle diagnostic tester.
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.
❑ Refer to ⇒ -5.1 Front Axle Speed Sensor”, page 52

3. Component Location Overview 27

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

4 Control Module and Hydraulic Unit

⇒ -4.1 Control Module and Hydraulic Unit”, page 28
⇒ A4.2 BS Control ModuleJ104/ABS Hydraulic UnitN55, Re‐
moving and Installing”, page 31
⇒ M4.3 odule, Separating from Hydraulic Unit”, page 47
⇒ M4.4 odule, Installing on Hydraulic Unit”, page 49

4.1 Overview - Control Module and Hydraulic Unit

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

28 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Bracket
❑ There are different ver‐
sions. Refer to the
⇒ Electronic Parts Cat‐
alog (ETKA).
2 - Nut
❑ 20 Nm
3 - Rubber Bushing
4 - Mounting Bracket
5 - ABS Hydraulic Unit -N55-
❑ Refer to ⇒
A4.2 BS Control Mod‐
uleJ104/ABS Hydraul‐
ic UnitN55, Removing
and Installing”, page
31
6 - ABS Control Module -
J104-
❑ Disconnect the connec‐
tor with the ignition
switched off
❑ Refer to ⇒
A4.2 BS Control Mod‐
uleJ104/ABS Hydraul‐
ic UnitN55, Removing
and Installing”, page
31
❑ Refer to ⇒ M4.3 odule, Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Separating from Hy‐ 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.
draulic Unit”, page 47
❑ Refer to ⇒ M4.4 odule,
Installing on Hydraulic
Unit”, page 49
7 - Brake Line
❑ From brake master cylinder to the hydraulic unit
❑ Identification: 5.25 mm diameter and union bolt with M10x1 thread
❑ Tightening Specifications
♦ With standard tool: 14 Nm
♦ With special tool Refer to ⇒ Fig. ““Brake lines tightening using special tools”“, page 30 12 Nm
8 - Brake Line
❑ From brake master cylinder to the hydraulic unit
❑ License plate: 6 mm diameter and union bolt with M12x1 thread
❑ Tightening Specifications
♦ With standard tool: 14 Nm
♦ With special tool Refer to ⇒ Fig. ““Brake lines tightening using special tools”“, page 30 12 Nm
9 - Torx Bolt
❑ Replace after removing
❑ Tighten the new Torx bolts in two steps, switching back and forth.
♦ Step 1: temporary tightening specification: 1 Nm to 1.5 Nm (to install the seal)
♦ Step 2: final tightening specification: 2.5 Nm
10 - Heat Shield

4. Control Module and Hydraulic Unit 29

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

❑ Attached version
❑ Bolted version. Refer to ⇒ Fig. ““Heat shield with threaded connection”“, page 30 .
❑ Installed, depending on the version
11 - Bolt
❑ 8 Nm

Brake lines tightening using special tools

Special tools and workshop equipment required

♦ Open Ring Spanner Insert - AF 11mm -V.A.G 1410/6-
♦ Torque Wrench - Universal Joint -V.A.G 1410/7-
♦ Mini Torque Wrench -VAS 6854-
Heat shield with threaded connection

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.

• Replace the self-locking nut after removing.

– Tighten the nut -1- for the heat shield -2- to 8 Nm.
– Press on the bracket for the lock washer -3- all the way.

30 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

4.2 ABS Control Module -J104-/ABS Hy‐

draulic Unit -N55-, Removing and In‐
stalling
⇒ A4.2.1 BS Control ModuleJ104/ABS Hydraulic UnitN55, Re‐
moving and Installing, LHD Vehicles”, page 31

4.2.1 ABS Control Module -J104-/ABS Hy‐

draulic Unit -N55-, Removing and In‐
stalling, LHD Vehicles
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

♦ If the ABS Control Module -J104- is faulty, it can be replaced

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.
separately.
♦ If the ABS Hydraulic Unit -N55- is faulty, it must be replaced
together with the ABS Control Module -J104-.
Special tools and workshop equipment required
♦ Vehicle Diagnostic Tester
♦ Open Ring Spanner Insert - AF 11mm -V.A.G 1410/6-

♦ Torque Wrench - Universal Joint -V.A.G 1410/7-

♦ Brake Pedal Actuator -V.A.G 1869/2-.

4. Control Module and Hydraulic Unit 31

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or

Brake Charger/Bleeder Unit -VAS 5234-

♦ Wrench - Brake Bleeder Set -VAS 5519-

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

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.

32 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Plugs from the Assembly Part Set -5Q0 698 311-: M10
-item 1- and M12 -item 2-

♦ Safety Gloves
Removing
– If the ABS Control Module -J104-/the hydraulic control unit
is replaced, select the “control module, replacing” program.
Refer to ⇒ E6.1 ntries”, page 21 .
– Insert the Brake Pedal Actuator -V.A.G 1869/2- -item A- be‐
tween the brake pedal and driver seat. Pretension the brake
pedal at least 60 mm. (By doing this, the valves in the brake
master cylinder are closed and the brake fluid reservoir does
not run empty.)

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.

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

TIP:
For certain tire combinations the removal of the wheels is re‐
quired.
– Remove the protective cap -3- from the bleed screw -1- on
the left front caliper.

4. Control Module and Hydraulic Unit 33

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Connect the collection bottle hose -2-.

– Open the bleed screw to reduce the pressure in the brake
system.
– Close the bleed screw and remove the collection bottle.
– Repeat the procedure on the left rear brake caliper.
• Do not remove the Brake Pedal Actuator -V.A.G 1869/2-.
– Remove the engine cover. Refer to ⇒ Engine Mechanical;
Rep. Gr. 10; Engine Cover; Engine Cover, Removing and
Installing.
Vehicle with TDI Engine:
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.

– Remove the emissions control module. Refer to ⇒ Engine

Mechanical; Rep. Gr. 26; Emissions Control; Emissions
Control Module, Removing and Installing.
– Remove the bolts -1- for the pendulum support.
Vehicle with 2.0L TFSI evo4:
– Remove the particulate filter. Refer to ⇒ Engine; Rep.
Gr. 26; Emissions Control; Catalytic Converter, Removing
and Installing.

34 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Vehicle with 2.5L FSI:

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.

– Loosen the hose clamps -2 and 3- and remove the air duct
hose.
– Loosen the hose clamps -1 and 2-.

– Press the release buttons on both sides and disconnect the

hose -3- for the crankcase ventilation at the air duct pipe.
– Remove the bolt -arrow- and the air duct pipe.
Heat shield with catch:

Not all models have the heat shield.

– Release the retainer -arrow-, pull the heat shield -1- off to
the left and remove it.

4. Control Module and Hydraulic Unit 35

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Heat shield with threaded connection:

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.

Not all models have the heat shield.

– Remove the nut -1- and remove the bracket with the lock
washer -3-.
– Remove the heat shield -2-.
Vehicle with 2.0L TFSI:
– Remove the drive axle heat shield. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 40; Drive Axle; Drive Axle Heat
Shield, Removing and Installing.
– Remove the Oxygen Sensor 1 before Catalytic Converter
-GX10-. Refer to ⇒ Engine; Rep. Gr. 24; Heated Oxygen
Sensor; Heated Oxygen Sensor, Removing and Installing.
– Remove the bolt -1- and free up the pressure pipe.

– Remove the bolt -1- and the screw-type clamp.

– Loosen the bolt -2- and push the catalytic converter to the
side.

36 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the bolts -arrows- and nuts -1- and remove the heat
shield.

– Disconnect the connector -1-.

– Remove the bolts -arrows- and move the Particulate Filter

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Differential Pressure Sensor -G1037-
permitted unless with
authorised by the
AUDI bracket
AG. AUDI AG todoes
thenot guarantee or accept any liability
side. with respect to the correctness of information in this document. Copyright by AUDI AG.

Continuation for All Vehicles:

– Unclip the wiring guide.

– Press the locking mechanism downward -arrow A-.
– Release the connector -arrow B-.
– Remove the connector -1-.
• Make sure that no brake fluid enters the control module
connector housing. This could lead to contact corrosion and
thereby cause the system to fail.
• A contaminated housing must be carefully cleaned with com‐
pressed air.

4. Control Module and Hydraulic Unit 37

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– To protect against escaping brake fluid, place enough lint-

free cloths in the area below the hydraulic control unit.
– Mark the brake lines on the hydraulic control module.

NOTICE
Risk of destroying the brake lines by bending.
– Never forcefully bend the brake lines in the hydraulic unit
area.

– Remove the union bolts for the brake lines in the sequence
-6 through 1- and push the brake lines slightly to the side.
– Seal brake lines and threaded holes with clean sealing
plugs.
Vehicles with high-voltage system:

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

– Remove the clip -1- and push the heat shield slightly for‐
ward.
– Remove the union bolts -arrows- for the brake lines.
– Free up the brake lines at the plenum chamber bulkhead
and push them aside.

38 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Continuation for All Vehicles:

– Pull the hydraulic control unit -1- upward -arrow- and remove
it.
– Should the hydraulic control module be replaced, remove
the bolts -arrows- and remove the mounting bracket -1-.

Installing
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 in the reverse order of removal while noting the following:

– Push the hydraulic control module -1- with the bracket into
the pins in the engine compartment -arrows-.
• The hydraulic control module must rest in all pins.
• When installing the hydraulic control module, make sure the
rubber buffer is not pushed out of the bracket.
• Only remove the plugs on the new hydraulic unit if the corre‐
sponding brake line is installed.
• If the plugs are removed too early from the hydraulic unit,
brake fluid can escape and the unit may not be sufficiently
filled or adequately bled.

4. Control Module and Hydraulic Unit 39

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Identification of the hydraulic unit.

A - Hydraulic Unit To Master Brake Cylinder Primary Piston

Circuit -HZ2-
B - Hydraulic Unit To Master Cylinder Secondary Piston Circuit
-HZ1-
1 - Hydraulic Unit To Right Front Brake Caliper -VR-
2 - Hydraulic Unit To Left Rear Brake Caliper -HL-
3 - Hydraulic Unit To Right Rear Brake Caliper -HR-
4 - Hydraulic Unit To Left Front Brake Caliper -VL-

NOTICE
Risk of destroying the brake lines by bending.
– Never forcefully bend the brake lines in the hydraulic unit
area.

– Insert all brake lines into the ABS Hydraulic Unit -N55-, in‐
stall all union bolts by hand and tighten in the sequence
-1 through 6- to the corresponding tightening specification.

– After securing the brake lines to the hydraulic unit select

the “Hydraulic valve interchange test” program. Refer to ⇒
E6.1 ntries”, page 21 .
– Follow the instructions
Protected inCopying
by copyright. the Vehicle
for private Diagnostic Testerindis‐
or commercial purposes, part or in whole, is not
play. permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
– Remove the Brake Pedal Actuator -V.A.G 1869/2-.
– Bleed the brake system. Refer to ⇒ S5.2 ystem, Bleeding”,
page 208 .
– Install the engine cover. Refer to ⇒ Engine Mechanical; Rep.
Gr. 10; Engine Cover; Engine Cover, Removing and Instal‐
ling.

40 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– After replacing the ABS Control Module -J104-/hydraulic

control unit complete the “Control Module, Replacing” pro‐
gram. Using the ⇒ Vehicle diagnostic tester.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -4.1 Control Module and Hydraulic Unit”, page 28
♦ Refer to ⇒ Fig. ““Brake lines tightening using special tools”“,
page 30
♦ Refer to ⇒ Fig. ““Heat shield with threaded connection”“,
page 30
♦ Refer to ⇒ Engine Mechanical; Rep. Gr. 21; Charge Air Sys‐
tem; Overview - Charge Air Hose Connections
♦ Refer to ⇒ Engine; Rep. Gr. 24; Heated Oxygen Sensor;
Overview - Heated Oxygen Sensor.
♦ Refer to ⇒ Engine Mechanical; Rep. Gr. 26; Exhaust Pipes/
Mufflers; Overview - Muffler.
♦ Refer to ⇒ Engine Mechanical; Rep. Gr. 26; Emissions Con‐
trol System; Overview - Emissions Control System.
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 40; Drive
Axle; Drive Axle Heat Shield, Removing and Installing.

4.2.2 ABS Control Module -J104-/ ABS Hy‐

draulic Unit -N55-, Removing and In‐
stalling, RHD -- Not for North American
Market
♦ If the ABS Control Module -J104- is faulty, it can be replaced
separately.
♦ If the ABS Hydraulic Unit -N55- is faulty, it must be replaced
together with the ABS Control
unless Module -J104-.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted 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
♦ Vehicle Diagnostic Tester
♦ Open Ring Spanner Insert - AF 11mm -V.A.G 1410/6-

4. Control Module and Hydraulic Unit 41

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Torque Wrench - Universal Joint -V.A.G 1410/7-

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Brake Pedal
permitted unless Actuator
authorised by-V.A.G 1869/2-.
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.

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or

Brake Charger/Bleeder Unit -VAS 5234-

42 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

♦ Plugs from the Assembly Part Set -5Q0 698 311-: M10
-item 1- and M12 -item 2-

♦ Safety Gloves
Removing
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– If the ABS Control Module -J104-/the hydraulic
permitted unless control
authorised by AUDI AG.unit
AUDI AG does not guarantee or accept any liability
is replaced, select the “controlwith
module,
respect toreplacing”
the correctnessprogram.
of information in this document. Copyright by AUDI AG.
Refer to ⇒ E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.
– Insert the Brake Pedal Actuator -V.A.G 1869/2- -item A- be‐
tween the brake pedal and driver seat. Pretension the brake
pedal at least 60 mm. (By doing this, the valves in the brake
master cylinder are closed and the brake fluid reservoir does
not run empty.)

4. Control Module and Hydraulic Unit 43

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

TIP:
For certain tire combinations the removal of the wheels is re‐
quired.
– Remove the protective cap -3- from the bleed screw -1- on
the left front caliper.

– Connect the collection bottle hose -2-.

– Open the bleed screw to reduce the pressure in the brake
system.
– Close the bleed screw and remove the collection bottle.
– Repeat the procedure on the left rear brake caliper.
• Do not remove the Brake Pedal Actuator -V.A.G 1869/2-.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Remove the engine cover. Refer to ⇒ permitted
Engine Mechanical;
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.
Rep. Gr. 10; Engine Cover; Engine Cover, Removing and
Installing.
– Remove the battery tray. Refer to ⇒ Electrical Equipment;
Rep. Gr. 27; Battery; Battery Tray, Removing and Installing.
– Press the locking mechanism downward -arrow A-.

– Release the connector -arrow B-.

– Remove the connector -1-.
• Make sure that no brake fluid enters the control module
connector housing. This could lead to contact corrosion and
thereby cause the system to fail.

44 Rep. Gr.45 - Antilock Brake System

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• A contaminated housing must be carefully cleaned with com‐

pressed air.
– To protect against escaping brake fluid, place enough lint-
free cloths in the area below the hydraulic control unit.

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

– Mark the brake lines on the hydraulic control module.

NOTICE
Risk of destroying the brake lines by bending.
– Never change the shape of the brake lines.

– First remove the union bolts -A and B- for the brake lines
and then free up the hydraulic control unit.
– Remove the union bolts -1 to 4- for the brake lines and free
up the hydraulic control unit.
– Seal brake lines and threaded holes with clean sealing
plugs.
– Remove the hydraulic control unit -1- with the bracket -2-
and the rubber bushing -arrows- upward and remove.

– Should the hydraulic control module be replaced, remove

the bolts -arrows- and remove the mounting bracket -1-.

4. Control Module and Hydraulic Unit 45

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Installing 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 in the reverse order of removal while noting the following:

– Push the hydraulic control module -1- with the bracket into
the pins in the engine compartment -arrows-.
• The hydraulic control module must rest in all pins.
• Only remove the plugs on the new hydraulic unit if the corre‐
sponding brake line is installed.
• If the plugs are removed too early from the hydraulic unit,
brake fluid can escape and the unit may not be sufficiently
filled or adequately bled.
• When installing the hydraulic control module, make sure the
rubber buffer is not pushed out of the bracket.
Identification of the hydraulic unit.

B - Hydraulic Unit To Master Brake Cylinder Primary Piston

Circuit -HZ2-
A - Hydraulic Unit To Master Cylinder Secondary Piston Circuit
-HZ1-

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
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3 - Hydraulic Unit To Right Front Brake Caliper -VR-

4 - Hydraulic Unit To Left Rear Brake Caliper -HL-
1 - Hydraulic Unit To Right Rear Brake Caliper -HR-
2 - Hydraulic Unit To Left Front Brake Caliper -VL-

NOTICE
Risk of destroying the brake lines by bending.
– Never change the shape of the brake lines.

– Insert all brake lines in the ABS Hydraulic Unit -N55-, insert
the union bolts in the sequence -1 to 6- by hand and then
tighten.

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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.

– After securing the brake lines to the hydraulic unit select

the “Hydraulic valve interchange test” program. Refer to ⇒
E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.
– Remove the Brake Pedal Actuator -V.A.G 1869/2-.
– Bleed the brake system. Refer to ⇒ S5.2 ystem, Bleeding”,
page 208 .
– After replacing the ABS Control Module -J104-/hydraulic
control unit complete the “Control Module, Replacing” pro‐
gram. Using the ⇒ Vehicle diagnostic tester.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -4.1 Control Module and Hydraulic Unit”, page 28
♦ Refer to ⇒ Fig. ““Brake lines tightening using special tools”“,
page 30

4.3 Control Module, Separating from Hy‐

draulic Unit
• The ABS Hydraulic Unit -N55- with the ABS Control Module
-J104- must be removed in order to separate the control
module and the hydraulic unit.
• The return flow pump may not be removed from the ABS
Hydraulic Unit -N55-.

4. Control Module and Hydraulic Unit 47

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Special tools and workshop equipment required

♦ ESD Work Surface -VAS 6613-

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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.

♦ Torx insert T25

Procedure
– Remove the hydraulic control unit. Refer to ⇒ A4.2 BS Con‐
trol ModuleJ104/ABS Hydraulic UnitN55, Removing and In‐
stalling”, page 31 .

NOTICE
There is a risk of destroying the control module through the
electrostatic charge and reduced cleanliness.
– Discharge electrostatic charge: touch the electro-static dis‐
charge work surface
– Protect the inner control module from moisture and dirt.

– Position the hydraulic unit with the control module from up‐
ward on the ESD Work Surface -VAS 6613-.

– Remove the three Torx bolts -arrows- and dispose of them

immediately.
– Push together the hydraulic unit with the loosened control
module all around and position with the control module up‐
ward on the ESD Work Surface -VAS 6613-.
– Remove the control module -1- without tilting carefully at an
angle upward out of the hydraulic unit -2-.

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Brake System - Edition 01.2023

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
• Blowing the
with control module
respect to the or ofhydraulic
correctness information inunit out withCopyright
this document. com‐by AUDI AG.
pressed air is not permitted.
• The valve bodies inside the hydraulic unit must not be dam‐
aged or bent.
– Check the hydraulic unit sealing surface, and if necessary,
clean with mineral spirits and a lint-free cloth.
– Cover the open hydraulic unit with a lint-free cloth.
• A damaged sealing surface must not be mechanically re‐
worked. A hydraulic unit with a damaged sealing surface
must be replaced.

NOTICE
There is a risk of damaging the control module through im‐
proper handling.
– Do not lift or remove the seal.

4.4 Control Module, Installing on Hydraulic

Unit
Special tools and workshop equipment required
♦ Torque Screwdriver -V.A.G 1624-

4. Control Module and Hydraulic Unit 49

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ ESD Work Surface -VAS 6613-

♦ Torx T25 Socket

Procedure
• Use the complete repair kit when installing.

NOTICE
Risk of damaging the control module through vibrations.
– Protect the control module from knocks and impacts.
– Never use a control module if it was dropped on the floor.

NOTICE
There is a risk of destroying the control module through the
electrostatic charge and reduced cleanliness.
– Discharge electrostatic charge: touch the electro-static dis‐
charge work surface
– Protect the inner control module from moisture and dirt.

• Open hydraulic unit position upward on the Electro-Static

Discharge Work Surface -VAS 6613-.
– Position the control module -1- without tilting carefully at an
angle upward out authorised
of the hydraulic
by AUDI AG. unit -2-.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 AUDI AG
with respect to the correctness of information in this document. Copyright by AUDI AG.

– Push together the hydraulic unit with the loosened control

module all around and position with the control module
downward on the ESD Work Surface -VAS 6613-.
– Install the new Torx bolt -arrows- by hand until the control
module touches the hydraulic unit evenly.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• If the bolts for the control module on the hydraulic unit are
difficult to install or cannot be tightened to the required tight‐
ening specification, then the hydraulic unit must be replaced.
– Tighten the bolts in two stages in a diagonal sequence.
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 the hydraulic control unit. Refer to ⇒ A4.2 BS Control

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

ModuleJ104/ABS Hydraulic UnitN55, Removing and Instal‐

ling”, page 31 .
Tightening Specifications
♦ Refer to ⇒ -4.1 Control Module and Hydraulic Unit”, page 28

4. Control Module and Hydraulic Unit 51

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

5 Sensors
⇒ -5.1 Front Axle Speed Sensor”, page 52
⇒ -5.2 Rear Axle Speed Sensor”, page 53
⇒ F5.3 ront ABS Wheel Speed SensorG45/Left Front ABS
Wheel Speed SensorG47, Removing and Installing”, page 55
⇒ R5.4 ear ABS Wheel Speed SensorG44/Left Rear ABS
Wheel Speed SensorG46, Removing and Installing”, page 56
⇒ S5.5 ensor Ring, Checking”, page 57

5.1 Overview - Front Axle Speed Sensor

1 - Wheel Hub with Wheel

Bearing
❑ The ABS sensor ring is
installed in the wheel
bearing
❑ Refer to ⇒ S5.5 ensor
Ring, Checking”, page
57
2 - Wheel Bearing Housing
3 - Bolt
❑ 8 Nm
4 - Front Speed Sensor
♦ Right Front ABS Wheel
Speed Sensor -G45-
♦ Left Front ABS Wheel
Speed Sensor -G47-
❑ Refer to ⇒ F5.3 ront
ABS Wheel Speed
SensorG45/Left Front
ABS Wheel Speed
SensorG47, Removing
and Installing”, page
55

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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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

5.2 Overview - Rear Axle Speed Sensor

⇒ -5.2.1 Rear Axle Speed Sensor, FWD and Rear Torsion
Beam Axle”, page 53
⇒ -5.2.2 Rear Axle Speed Sensor, FWD and Rear Multi-Link
Axle”, page 53
⇒ -5.2.3 Rear Axle Speed Sensor, AWD”, page 54

5.2.1 Overview - Rear Axle Speed Sensor, FWD and Rear Torsion Beam Axle

1 - Wheel Hub with Wheel

Bearing
❑ The sensor ring for the
ABS is located on the
wheel bearing
❑ Refer to ⇒ S5.5 ensor
Ring, Checking”, page
57
2 - Torsion Beam Axle
3 - Rear Speed Sensor
♦ Right Rear ABS Wheel
Speed Sensor -G44-
♦ Left Rear ABS Wheel
Speed Sensor -G46-
❑ Refer to ⇒ R5.4 ear
ABS Wheel Speed
SensorG44/Left Rear
ABS Wheel Speed
SensorG46, Removing
and Installing”,
Protectedpage
by copyright. Copying for private or commercial purposes, in part or in whole, is not
56 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 - Bolt
❑ 8 Nm

5.2.2 Overview - Rear Axle Speed Sensor, FWD and Rear Multi-Link Axle

5. Sensors 53
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Wheel Hub with Wheel

Bearing
❑ The ABS sensor ring is
installed in the wheel
bearing
❑ Refer to ⇒ S5.5 ensor
Ring, Checking”, page
57
2 - Wheel Bearing Housing
3 - Rear Speed Sensor
♦ Right Rear ABS Wheel
Speed Sensor -G44-
♦ Left Rear ABS Wheel
Speed Sensor -G46-
❑ Refer to ⇒ R5.4 ear
ABS Wheel Speed
SensorG44/Left Rear
ABS Wheel Speed
SensorG46, Removing
and Installing”, page
56
4 - Bolt
❑ 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
with respect to the correctness of information in this document. Copyright by AUDI AG.

5.2.3 Overview - Rear Axle Speed Sensor, AWD

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Wheel Bearing Unit

❑ The ABS sensor ring is
installed in the wheel
bearing
❑ Refer to ⇒ S5.5 ensor
Ring, Checking”, page
57
2 - Wheel Bearing Housing
3 - Speed Sensor
♦ Right Rear ABS Wheel
Speed Sensor -G44-
♦ Left Rear ABS Wheel
Speed Sensor -G46-
❑ Refer to ⇒ R5.4 ear
ABS Wheel Speed
SensorG44/Left Rear
ABS Wheel Speed
SensorG46, Removing
and Installing”, page
56
4 - Bolt
❑ 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

5.3 Right Front ABS Wheel Speed Sensor

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

-G45-/Left Front ABS Wheel Speed

Sensor -G47-, Removing and Installing
Special tools and workshop equipment required
♦ Polycarbamide Grease. Refer to ⇒ Electronic Parts Catalog
(ETKA).
Removing
– Remove the affected front wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– Disconnect the connector -2- from the speed sensor.

5. Sensors 55
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the bolt -1- and remove the speed sensor from the
wheel bearing housing.
Installing
Install in the reverse order of removal while noting the following:
– Clean the inner surface of the hole before inserting the
speed sensor.
– Coat the speed sensor before inserting all around with Pol‐
ycarbamide Grease at the same time omit the top of the
sensor.
– Insert the speed sensor all the way by hand and tighten.
Tightening Specifications
♦ Refer to ⇒ -5.1 Front Axle Speed Sensor”, page 52
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

5.4 Right Rear ABS Wheel Speed Sen‐

sor -G44-/Left Rear ABS Wheel Speed
Sensor -G46-, Removing and Installing
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Special tools and workshop equipment required 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.
♦ Polycarbamide Grease. Refer to ⇒ Electronic Parts Catalog
(ETKA).
Removing FWD vehicle with torsion beam rear axle:

– Disconnect the connector -2- from the speed sensor.

– Remove the bolt -1- and remove the speed sensor.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Removing FWD vehicle with multi-link rear axle:

– Disconnect the connector -2- from the speed sensor.

– Remove the bolt -1- and remove the speed sensor.
AWD vehicles removing:

– Disconnect the connector -2- from the speed sensor.

– Remove the bolt -1- and remove the speed sensor.
Installing
Install in the reverse order of removal while noting the following:
– Clean the inner surface of the hole before inserting the
speed sensor.
– Coat the speed sensor before inserting all around with Pol‐
ycarbamide Grease at the same time omit the top of the
sensor.
– Insert the speed sensor all the way by hand and tighten.
Tightening Specifications
♦ Refer to ⇒ -5.2 Rear Axle Speed Sensor”, page 53

5.5 ABS Sensor Ring, Checking

Special tools and workshop equipment required
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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.

5. Sensors 57
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Gauge - Sender Wheel -T10473-

Procedure
• Removing the wheel bearing unit. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 40; Wheel Bearing; Wheel Bear‐
ing Unit, Removing and Installing or ⇒ Suspension, Wheels,
Steering; Rep. Gr. 42; Wheel Bearing, Trailing Arm; Wheel
Bearing Unit, Removing and Installing.
– Check the sensor ring for the ABS speed sensor using the
Gauge - Sender Wheel -T10473- as shown all around.

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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.
1- Wheel Bearing Unit
2- Seal with Integrated Sensor Ring for ABS Speed Sensor
Sensor ring for ABS speed sensor test diagram.

A - Sensor Ring OK

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

B - Sensor Ring Faulty

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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.

5. Sensors 59
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

46 – Mechanical Components
1 Safety Precautions
Observe the safety instructions. Refer to ⇒ P2 recautions”, page
3.

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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.

60 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2 Front Brakes
⇒ -2.1 Front Brakes”, page 61
⇒ P2.2 ads, Removing and Installing”, page 75
⇒ C2.3 aliper, Removing and Installing”, page 98
⇒ C2.4 aliper, Replacing”, page 106
⇒ C2.5 arrier, Removing and Installing”, page 119
⇒ R2.6 otor, Removing and Installing”, page 120
⇒ S2.7 hield, Removing and Installing”, page 122 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
⇒ P2.8 ad Wear Indicator Wire, Removing and Installing”, page
with respect to the correctness of information in this document. Copyright by AUDI AG.

123

2.1 Overview - Front Brakes

⇒ -2.1.1 Single-Piston Brake 1ZD”, page 61
⇒ -2.1.2 Single-Piston Brake Excluding 1ZD”, page 64
⇒ -2.1.3 Dual-Piston Brakes”, page 67
⇒ -2.1.4 Six-Piston Steel Brakes”, page 69
⇒ -2.1.5 Six-Piston Ceramic Brake”, page 72

2.1.1 Overview - Single-Piston Brake 1ZD

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

2. Front Brakes 61
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Caliper
❑ Allocation. Refer to the
⇒ Electronic Parts Cat‐
alog (ETKA).
❑ Do not disconnect the
brake hose when re‐
placing a brake pad
❑ Refer to ⇒ C2.3.1 alip‐
er, Removing and In‐
stalling, Single and Du‐
al-Piston Brakes”, page
98
❑ Refer to ⇒ C2.4.1 alip‐
er, Replacing, Sin‐
gle and Dual-Piston
Brakes”, page 106
❑ Servicing. Refer to
⇒ C2.2.1 aliper Pis‐
ton, Removing and In‐
stalling, Single-Piston
Brake”, page 171 .
2 - Bleed Screw
❑ 11 Nm
3 - Protective Cap
4 - Cap
5 - Guide Pin
❑ Check ease of move‐
ment
❑ 35 Nm
6 - Brake Pad Retaining Plate
7 - Wheel Bearing Housing
8 - Bolt
❑ 200 Nm
9 - Bracket
❑ For the brake line/hose
10 - Brake Line
❑ Do not change the bending shape.
❑ Replace a damaged or bent brake line
❑ 14 Nm
11 - Springs
❑ Replace if damaged
12 - Brake Hose
❑ Make sure the brake hose is routed correctly. Make sure the brake hose is not pinched, bent, twisted
or rubbing against the vehicle
❑ Replace if damaged
❑ Make sure that tabs are properly seated in the grooves on the bracket.
13 - Bracket
❑ For brake hose and wire 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
14 - Bolt with respect to the correctness of information in this document. Copyright by AUDI AG.

❑ 8 Nm
15 - Banjo Bolt

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
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❑ Permanent with seals

❑ Clean any corrosion from the sealing surface on the brake caliper
❑ If damaged, replace the brake hose
❑ 35 Nm
16 - Brake Shield
❑ Refer to ⇒ S2.7 hield, Removing and Installing”, page 122
17 - Brake Rotor
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Refer to ⇒ R5.4 otor, Checking”, page 13
❑ Wear limit specified on the brake rotor
❑ Always replace on both sides of the axle. Replace the brake pads as well.
❑ Refer to ⇒ R2.6 otor, Removing and Installing”, page 120
18 - Bolt
❑ 8 Nm
19 - Bolt
❑ 12 Nm
20 - Spring
21 - Brake Carrier
❑ Refer to ⇒ C2.5 arrier, Removing and Installing”, page 119
22 - Brake Pad Retaining Plate
23 - Brake Pads
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Checking the brake pads, wear limit. Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900; Maintenance Procedures; Brake Pad
Thickness, Checking.
❑ Inner right brake pad with brake pad wear sensor
❑ Refer to ⇒ Fig. ““Brake pads 1ZD installation position”“, page 63
❑ Refer to ⇒ P2.2.1 ads, Removing and Installing, Single-Piston Brake 1ZD”, page 75

Brake pads 1ZD installation position

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- Clip the inner brake pad with the spring -arrow- into the
brake caliper piston

2. Front Brakes 63
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2- Engage the outer brake pad into the brake carrier

2.1.2 Overview - Single-Piston Brake Excluding 1ZD

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

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.

64 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Caliper
❑ Allocation. Refer to the
⇒ Electronic Parts Cat‐
alog (ETKA).
❑ Do not disconnect the
brake hose when re‐
placing a brake pad
❑ Refer to ⇒ C2.3.1 alip‐
er, Removing and In‐
stalling, Single and Du‐
al-Piston Brakes”, page
98
❑ Refer to ⇒ C2.4.1 alip‐
er, Replacing, Sin‐
gle and Dual-Piston
Brakes”, page 106
❑ Servicing. Refer to
⇒ C2.2.1 aliper Pis‐
ton, Removing and In‐
stalling, Single-Piston
Brake”, page 171 .
2 - Bleed Screw
❑ 11 Nm
3 - Protective Cap
4 - Bolt
❑ Self-locking
❑ Replace after removing
❑ 35 Nm
5 - Dust Protector
❑ Replace if damaged
6 - Guide Pin
❑ Check ease of move‐
ment
7 - Wheel Bearing Housing
8 - Bolt
❑ 200 Nm
9 - Banjo Bolt
❑ Permanent with seals
❑ Clean any corrosion from the sealing surface on the brake caliper
❑ If damaged, replace the brake hose
❑ 35 Nm
10 - Brake Hose
❑ Make sure the brake hose is routed correctly. Make sure the brake hose is not pinched, bent, twisted
or rubbing against the vehicle
❑ Replace if damaged
❑ Make sure that tabs are properly seated in the grooves on the bracket.
11 - Bracket
❑ For the brake line/hose
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
12 - Brake Line
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.
❑ 14 Nm
13 - Springs

2. Front Brakes 65
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

❑ Replace if damaged
14 - Bracket
❑ For brake hose and wire
15 - Bolt
❑ 8 Nm
16 - Brake Shield
❑ Refer to ⇒ S2.7 hield, Removing and Installing”, page 122
17 - Brake Rotor
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Refer to ⇒ R5.4 otor, Checking”, page 13
❑ Wear limit specified on the brake rotor
❑ Always replace on both sides of the axle. Replace the brake pads as well.
❑ Refer to ⇒ R2.6 otor, Removing and Installing”, page 120
18 - Bolt
❑ 8 Nm
19 - Bolt
❑ 12 Nm
20 - Brake Carrier
❑ Refer to ⇒ C2.5 arrier, Removing and Installing”, page 119
21 - Brake Pads
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Inner right brake pad with brake pad wear sensor
❑ Checking the brake pads, wear limit. Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake PadProtected
Thickness, Checking
by copyright. Copying for/private
⇒ Maintenance; Booklet
or commercial purposes, in part 900; Maintenance
or in whole, is not Procedures; Brake Pad
Thickness,permitted
Checking.
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.
❑ Refer to ⇒ P2.2.2 ads, Removing and Installing, Single-Piston Brake excluding 1ZD, Dual-Piston
Brakes”, page 81
❑ Refer to ⇒ Fig. ““Installation position of the brake pads.”“, page 66
22 - Trim
❑ Only installed depending on the model
❑ No replacement part
23 - Clamping Sleeve
❑ Only installed depending on the model
❑ No replacement part

Installation position of the brake pads.

Meaning of the letters -arrows-:

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

H, Q, BS, CV, = Left and Right Outer Brake Pad

BI or EA
X, O, BT, CW, = Left Inner Brake Pad
BJ or EB
Y, P, BU, CX, = Right Inner Brake Pad
BK or BU

2.1.3 Overview - Dual-Piston Brakes

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

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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.

2. Front Brakes 67
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Caliper
❑ Allocation. Refer to the
⇒ Electronic Parts Cat‐
alog (ETKA).
❑ Do not disconnect the
brake hose when re‐
placing a brake pad
❑ Refer to ⇒ C2.3.1 alip‐
er, Removing and In‐
stalling, Single and Du‐
al-Piston Brakes”, page
98
❑ Refer to ⇒ C2.4.1 alip‐
er, Replacing, Sin‐
gle and Dual-Piston
Brakes”, page 106
❑ Servicing. Refer to
⇒ C2.2.2 aliper Pis‐
ton, Removing and
Installing, Dual-Piston
Brake”, page 174 .
2 - Bleed Screw
❑ 11 Nm
3 - Protective Cap
4 - Bolt
❑ Self-locking
❑ Replace after removing
❑ 35 Nm
5 - Brake Pads
❑ Allocation. Refer to the
⇒ Electronic Parts Cat‐
alog (ETKA).
❑ Checking the brake
pads, wear limit. Refer
to ⇒ Maintenance; Booklet 860; Maintenance Procedures; Brake Pad Thickness, Checking / ⇒ Main‐
tenance; Booklet 900; Maintenance Procedures; Brake Pad Thickness, Checking.
❑ Always replace on both sides of the axle.
❑ Refer to ⇒ P2.2.2 ads, Removing and Installing, Single-Piston Brake excluding 1ZD, Dual-Piston
Brakes”, page 81
❑ Inner right brake pad with brake pad wear sensor
6 - Brake Pad Retaining Plate 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
7 - Guide Pin with respect to the correctness of information in this document. Copyright by AUDI AG.

❑ Check ease of movement

8 - Dust Protector
❑ Replace if damaged
9 - Wheel Bearing Housing
10 - Bolt
❑ 200 Nm
11 - Bracket
❑ For the brake line/hose
12 - Brake Line
❑ 14 Nm

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

13 - Springs
❑ Replace if damaged
14 - Brake Hose
❑ Make sure the brake hose is routed correctly. Make sure the brake hose is not pinched, bent, twisted
or rubbing against the vehicle
❑ Replace if damaged
❑ Make sure that tabs are properly seated in the grooves on the bracket.
15 - Bracket
❑ For brake hose and wire
16 - Bolt
❑ 8 Nm
17 - Banjo Bolt
❑ Permanent with seals
❑ Clean any corrosion from the sealing surface on the brake caliper
❑ If damaged, replace the brake hose
❑ 35 Nm
18 - Brake Shield
❑ Refer to ⇒ S2.7 hield, Removing and Installing”, page 122
19 - Brake Rotor
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Refer to ⇒ R5.4 otor, Checking”, page 13
❑ Wear limit specified on the brake rotor
❑ Always replace on both sides of the axle. Replace the brake pads as well.
❑ Refer to ⇒ R2.6 otor, Removing and Installing”, page 120
20 - Bolt
❑ 8 Nm
21 - Bolt
❑ 12 Nm
22 - Brake Carrier
❑ Refer to ⇒ C2.5 arrier, Removing and Installing”, page 119
23 - Trim
❑ Only installed depending on the model
❑ No replacement part
24 - Clamping Sleeve
❑ Only installed depending on the model
❑ No replacement part
25 - Brake Pad Retaining Plate
❑ Brake pad anti-friction plates
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.

2.1.4 Overview - Six-Piston Steel Brakes

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

2. Front Brakes 69
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Pad Springs

❑ Replace when replac‐
ing the pads
❑ Check for proper seat‐
ing
2 - Bleed Screw
❑ Quantity: 2
❑ 11 Nm
3 - Protective Cap
4 - Brake Pad Wear Indicator
Wire
❑ Replace when replac‐
ing the pads
❑ Refer to ⇒ P2.8 ad
Wear Indicator Wire,
Removing and Instal‐
ling”, page 123
5 - Brake Hose
❑ Make sure the brake
hose is routed correct‐
ly. Make sure the brake
hose is not pinched,
bent, twisted or rubbing
against the vehicle.
❑ Replace if damaged
❑ Make sure that tabs are
properly seated in the
grooves on the bracket.
❑ Tightening specifica‐
tion: brake hose to
brake caliper, 14 Nm
6 - Bracket
❑ For the brake line/hose
7 - Brake Line
❑ 14 Nm
8 - Springs
❑ Replace if damaged
9 - Bolt
❑ 200 Nm
10 - Wheel Bearing Housing
11 - Bracket
❑ For brake hose and wire
12 - Bolt
❑ 8 Nmpermitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

with respect to the correctness of information in this document. Copyright by AUDI AG.
13 - Brake Shield
❑ Refer to ⇒ S2.7 hield, Removing and Installing”, page 122
14 - Bolt
❑ 12 Nm
15 - Brake Rotor
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).

70 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

❑ Refer to ⇒ R5.4 otor, Checking”, page 13

❑ Wear limit specified on the brake rotor
❑ Always replace on both sides of the axle. Replace the brake pads as well.
❑ Refer to ⇒ R2.6 otor, Removing and Installing”, page 120
16 - Bolt
❑ 4.5 Nm
17 - Brake Pad Retaining Plate
❑ Replace when replacing the pads
❑ Check for proper seating
18 - Brake Pad Retaining Plate
❑ Replace when replacing the pads
❑ Check for proper seating
19 - Brake Pads
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Checking the brake pads, wear limit. Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900; Maintenance Procedures; Brake Pad
Thickness, Checking.
❑ Always replace on both sides of the axle.
❑ Refer to ⇒ P2.2.3 ads, Removing and Installing, Six-Piston Steel Brake”, page 88
❑ Inner right brake pad with brake pad wear sensor
20 - Brake Caliper
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Do not disconnect the brake hose when replacing a brake pad
❑ Refer to ⇒ C2.3.2 aliper, Removing and Installing, Six-Piston Steel Brake”, page 101
❑ Refer to ⇒ C2.4.2 aliper, Replacing, Six-Piston Steel Brake”, page 110
❑ Servicing. Refer to ⇒ C2.2.3 aliper Piston, Removing and Installing, Six-Piston Brake”, page 178 .

Do not loosen the threaded connections -arrows A- on the

brake caliper

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.

Example illustration

2. Front Brakes 71
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
Improper handling increases the risk of destroying the brake
caliper.
– Never loosen the bolts on the brake caliper.

2.1.5 Overview - Six-Piston Ceramic Brake

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

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.

72 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Pad Spring

❑ Note the installation po‐
sition. Refer to ⇒ page
96 .
2 - Brake Pad Wear Indicator
Wire
❑ Replace when replac‐
ing the pads
❑ Refer to ⇒ P2.8.2 ad
Wear Indicator Wire,
Removing and Instal‐
ling, Six-Piston Ceram‐
ic Brake”, page 125
3 - Bolt
❑ 25 Nm
4 - Bleed Screw
❑ 18 Nm
5 - Bracket
❑ for brake hose 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
6 - Brake Hose with respect to the correctness of information in this document. Copyright by AUDI AG.

❑ Make sure the brake

hose is routed correct‐
ly. Make sure the brake
hose is not pinched,
bent, twisted or rubbing
against the vehicle.
❑ Replace if damaged
❑ Make sure that tabs are
properly seated in the
grooves on the bracket.
❑ Tightening specifica‐
tion: brake hose to
brake caliper, 14 Nm
7 - Bolt
❑ 25 Nm
8 - Protective Cap
9 - Springs
❑ Replace if damaged
10 - Bracket
❑ For the brake line/hose
11 - Brake Line
❑ Do not change the bending shape.
❑ Replace a damaged or bent brake line
❑ Tightening Specifications
♦ With standard tool: 14 Nm
♦ With special tool Refer to ⇒ Fig. ““Brake lines tightening using special tools”“, page 190 12 Nm
12 - Bolt
❑ 200 Nm
13 - Wheel Bearing Housing
14 - Bracket

2. Front Brakes 73
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

❑ for brake hose

15 - Bolt
❑ 8 Nm
16 - Brake Shield
❑ Refer to ⇒ S2.7 hield, Removing and Installing”, page 122
17 - Bolt
❑ 12 Nm
18 - Brake Rotor
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Wear limit specified on the brake rotor
❑ Refer to ⇒ R5.4.2 otors, Checking, Ceramic Brakes”, page 16
❑ Replace the damaged or worn brake rotor individually, not on both sides of the axle
❑ If only one brake rotor is replaced, the brake pads can be reused, if they do not show any damages.
❑ Pay attention to the side of the vehicle specified on the brake rotor “L”/“R” and the running direction
“arrow”
❑ Refer to ⇒ R2.6.2 otor, Removing and Installing, Ceramic Brakes”, page 121
19 - Bolt
❑ 4.5 Nm
20 - Brake Caliper
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Do not disconnect the brake hose when replacing a brake pad
❑ Refer to ⇒ C2.3.3 aliper, Removing and Installing, Six-Piston Ceramic Brake”, page 103
❑ Refer to ⇒ C2.2.3 aliper Piston, Removing and Installing, Six-Piston Brake”, page 178
21 - Brake Pad Pin
❑ Replace when replacing the pads
22 - Brake Pads
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Checking the brake pads, wear limit. Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900; Maintenance Procedures; Brake Pad
Thickness, Checking.
❑ Always replace on both sides of the axle.
❑ Refer to ⇒Protected
P2.2.4byads, Removing
copyright. and Installing,
Copying for private Six-Piston
or commercial purposes, in partCeramic
or in whole, isBrake”,
not page 92
❑ Inner right brake pad with brake pad wear sensor
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.

23 - Balance Springs

Do not loosen the threaded connections -arrows- on the brake

caliper

74 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
Improper handling increases the risk of destroying the brake
caliper.
– Never loosen the bolts -arrows- and guide pins at the
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
breakwith
caliper.
respect to the correctness of information in this document. Copyright by AUDI AG.

2.2 Brake Pads, Removing and Installing

⇒ P2.2.1 ads, Removing and Installing, Single-Piston Brake
1ZD”, page 75
⇒ P2.2.2 ads, Removing and Installing, Single-Piston Brake ex‐
cluding 1ZD, Dual-Piston Brakes”, page 81
⇒ P2.2.3 ads, Removing and Installing, Six-Piston Steel Brake”,
page 88
⇒ P2.2.4 ads, Removing and Installing, Six-Piston Ceramic
Brake”, page 92

2.2.1 Brake Pads, Removing and Installing,

Single-Piston Brake 1ZD
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required
♦ Piston Resetting Tool -T10145-

2. Front Brakes 75
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Removing
• Label the brake pads when removing if they are going to
be used again. Install in the same position, otherwise the
braking effect will be uneven.
– Remove the affected front wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– Disconnect the connector -arrow- for the brake pad wear
indicator contact from the right brake caliper.

CAUTION
There is a risk of injury because the spring is tensioned.
The spring can jump out and cause eye or skin injury.
– Hold the spring with a hand.
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.

– Pry out the spring -2- using a screwdriver -3- out of the
springs -arrow B- on the brake caliper -1- -arrow A- and
remove.
– Remove the guide pins -arrows- and remove the brake cali‐
per.

76 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
There is a risk of damaging the brake hose due to the weight
of the brake caliper.
– Never let the brake caliper hang on the brake hose.

– Hang the brake caliper using a suitable wire.

NOTICE
There is a risk of damaging the brake caliper piston if handled
incorrectly.
– Never activate the brakes if the brake caliper is removed.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

– Remove the brake pads and brake

withpad retaining plates
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.
-1 and 2-.

Installing
Install in the reverse order of removal while noting the following:
– Check the brake rotors for wear and damage. Refer to ⇒
R5.4 otor, Checking”, page 13 .
• Use the complete repair kit when installing new brake pads.
• Components to be used when installing new brake pads.
Refer to ⇒ Electronic Parts Catalog (ETKA).

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

2. Front Brakes 77
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• Check the protective caps of the brake caliper pistons for

damage and install the complete repair kit, if necessary. Re‐
fer to ⇒ C2.2 aliper Piston, Removing and Installing”, page
171 .
• Check the bearing bushings of the guide pins for damage
and check that the guide pins move easily. Install the com‐
plete repair kit, if necessary. Refer to ⇒ B2.3 ushing and
Guide Pin, Replacing”, page 181 .

NOTICE
There is a risk of contamination and paint damage from leak‐
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

ing brake fluid.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

– Check the brake fluid level before pushing the brake cali‐
per piston back into the brake cylinders.

– If the brake fluid is up to the “MAX” marking on used brake

pads, it must be extracted.
– Evacuate the brake fluid -2- in the brake fluid reservoir with
the screen installed -1-, using the Bleeding Equipment Brake
Filling and Bleeding Equipment -VAS 6860- or Brake Charg‐
er/Bleeder Unit Brake Charger/Bleeder Unit -VAS 5234- (ex‐
ample illustration).
– Use the Piston Resetting Tool -T10145- -item A- to press the
brake caliper piston completely back into the brake caliper
(example illustration).

– Clean the brake carrier on the contact surfaces -1 and 2- for

the brake carrier.

78 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– If re-using, install the marked brake pads in the same loca‐

tion.
– If equipped, remove the protective film from the backing
plate of the brake pad.
– Bring the brake pad retaining plates -1 and 2- as shown in
the installation position.

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 the brake pads while paying attention to the installed

position. Refer to ⇒ Fig. ““Brake pads 1ZD installation posi‐
tion”“, page 63 .
– Bring the brake caliper into its installed position and tighten
the guide pins arrows.

• Make sure the brake hose is routed correctly.

2. Front Brakes 79
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• Make sure the brake hose is not blocked, bent, twisted or

rubbing against the vehicle.

CAUTION
There is a risk of injury because the spring is tensioned.
The spring can jump out and cause eye or skin injury.
– Hold the spring with a hand.

– Bring the spring -2- using a screwdriver -3- into the installa‐
tion position -arrow A- and push it in the guides -arrow B- on
the brake caliper -1-.
– Connect the connector -arrow- for the brake pad wear indi‐
cator contact on the right brake caliper.

– With the vehicle stationary, firmly press the

Protected brake pedal
by copyright. Copying sev‐
for private or commercial purposes, in part or in whole, is not
eral times so that the brake pads inpermitted
the operating condition
unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

properly sit in their respective position.

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

– Check brake fluid level, and fill if necessary.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

80 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Tightening Specifications
♦ Refer to ⇒ -2.1.1 Single-Piston Brake 1ZD”, page 61
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

2.2.2 Brake Pads, Removing and Installing,

Single-Piston Brake excluding 1ZD,
Dual-Piston Brakes
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
Allocation of thepermitted
PR number. Referbyto
unless authorised ⇒ AG.
AUDI D4.1AUDIata, Brakes”,
AG does not guarantee or accept any liability
page 9 . with respect to the correctness of information in this document. Copyright by AUDI AG.

Special tools and workshop equipment required

♦ Piston Resetting Tool -T10145-

Removing
• Label the brake pads when removing if they are going to
be used again. Install in the same position, otherwise the
braking effect will be uneven.
– Remove the affected front wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– Disconnect the connector -arrow- for the brake pad wear
indicator contact from the right brake caliper.

– Remove the bolts -arrows- by counterholding at the guide

pins -1 and 2-.

2. Front Brakes 81
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the brake caliper.

NOTICE
There is a risk of damaging the brake hose due to the weight
of the brake caliper.
– Never let the brake caliper hang on the brake hose.

– Hang the brake caliper using a suitable wire.

NOTICE
There is a risk of damaging the brake caliper piston if handled
incorrectly.
– Never activate the brakes if the brake caliper is removed.

– Remove the outer brake pad -1- first at an angle outward.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
– Remove the brake pad in between the tabs -arrow- of the
springs -3- toward the front.
– Repeat the procedure on the inner brake pad.

82 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the springs -2- from the brake carrier -1-.

Installing
Install in the reverse order of removal while noting the following:
– Check the brake rotors for wear and damage. Refer to ⇒
R5.4 otor, Checking”, page 13 .
• Use the complete repair kit when installing new brake pads.
• Components to be used when installing new brake pads.
Refer to ⇒ Electronic Parts Catalog (ETKA).

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

• Check the protective caps of the brake caliper pistons for
damage and install the complete repair kit, if necessary. Re‐
fer to ⇒ C2.2 aliper Piston, Removing and Installing”, page
171 .
• Check the bearing bushings of the guide pins for damage
and check that the guide pins move easily. Install
by AUDIthe
AG. com‐
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised AUDI AG does not guarantee or accept any liability
plete repair kit, if necessary.with
Refer toto⇒
respect theB2.3 ushing
correctness and in this document. Copyright by AUDI AG.
of information
Guide Pin, Replacing”, page 181 .

2. Front Brakes 83
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
There is a risk of contamination
permitted unless authorised byand
AUDI paint
AG. AUDIdamage
AG does not from leak‐
guarantee or accept any liability
ing brake fluid.with respect to the correctness of information in this document. Copyright by AUDI AG.
– Check the brake fluid level before pushing the brake cali‐
per piston back into the brake cylinders.

– If the brake fluid is up to the “MAX” marking on used brake

pads, it must be extracted.
– Evacuate the brake fluid -2- in the brake fluid reservoir with
the screen installed -1-, using the Brake Filling and Bleeding
Equipment -VAS 6860- or Brake Charger/Bleeder Unit -VAS
5234- (example illustration).
Single-Piston Brakes:

– Use the Piston Resetting Tool -T10145- -item A- to press the

brake caliper piston completely back into the brake caliper.
Dual-Piston Brakes:

84 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Place a wooden board -3- or a brake pad in the shaft, so that

both brake caliper pistons are reset evenly in the brake pad
-1- using the Piston Resetting Tool -T10145- -item 2-.
Continuation for all brake types:

– Protected
Cleanbythe brake carrier -1- at the contact surfaces -2- for the
copyright. Copying for private or commercial purposes, in part or in whole, is not

brake pads.
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.

– Insert the springs -2- at the brake carrier -1-, lock and pay
attention to proper seating.

– If equipped, remove the protective film from the backing

plate of the brake pad.
– If re-using, install the marked brake pads in the same loca‐
tion.
– Install the brake pads while paying attention to the installed
position. Refer to ⇒ Fig. ““Installation position of the brake
pads.”“, page 66 .
– Push the outer brake pad -1- first at an angle between the
springs -3- -arrow- and at the same time do not bend the
springs.

2. Front Brakes 85
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Pivot the brake pad to the brake rotor.

– Repeat the procedure on the inner brake pad.
– Align the brake pads -3- in the brake pad springs -2-.

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.

• After installing the brake pads pay attention that all brake
pad springs are seated correctly.
– Push the brake caliper over the installed brake pads.

86 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Tighten the brake caliper bolts -arrows- to the required

tightening specification by counterholding
Protected by copyright. Copying for private or at the guide
commercial pins
purposes, in part or in whole, is not
-1 and 2-. 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.
• Make sure the brake hose is routed correctly.
• Make sure the brake hose is not pinched, bent, twisted or
rubbing against the vehicle.
– Connect the connector -arrow- for the brake pad wear indi‐
cator contact on the right brake caliper.

– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
– Check brake fluid level, and fill if necessary.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1 Front Brakes”, page 61
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

2. Front Brakes 87
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2.2.3 Brake Pads, Removing and Installing,

Six-Piston Steel Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required
♦ Piston Resetting Tool -T10145-

Removing
• Label the brake pads when removing if they are going to
be used again. Install in the same position, otherwise the
braking effect will be uneven.
– Remove the brake caliper. Refer to ⇒ C2.3.2 aliper, Remov‐
ing and Installing, Six-Piston Steel Brake”, page 101 .
– Disconnect the connector -1-.

– Free up the wire by opening the protective cap -3- and dis‐
engage the wire from the brake caliper.
– If the brake pads are being replaced, place the Piston Reset‐
ting Tool -T10145- with a wooden block -1- placed between
it and the old brake pads and push the brake caliper pistons
all the way back into the brake caliper.

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.

88 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the brake pads -3 and 4- one after the other toward
the center of the brake caliper.

– Unclip the brake pad retaining plate -1-.

– If the brake pads are replaced, unclip the top and bottom
brake pad springs -2-.
• If reusing the brake pads check the brake pad spring and the
brake pad retaining plate for damage, if necessary replace.
• Do not change the shape of the brake pad spring and brake
pad retaining plate.
Installing
Install in the reverse order of removal while noting the following:
– Check the brake rotors for wear and damage. Refer to ⇒
R5.4 otor, Checking”, page 13 .
• Use the complete repair kit when installing new brake
Protected by copyright. Copyingpads.
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
• Components to be used when installing newtobrake
with respect pads.of information in this document. Copyright by AUDI AG.
the correctness
Refer to ⇒ Electronic Parts Catalog (ETKA).

2. Front Brakes 89
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

• Check the protective caps of the brake caliper pistons for
damage and install the complete repair kit, if necessary.
Refer to ⇒ C2.2.3 aliper Piston, Removing and Installing,
Six-Piston Brake”, page 178 .

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Check the brake fluid level before pushing the brake cali‐
per piston back into the brake cylinders.

– If the brake fluid is up to the “MAX” marking on used brake

pads, it must be extracted.
– Evacuate the brake fluid -2- in the brake fluid reservoir with
the screen installed -1-, using the Brake Filling and Bleeding
Equipment -VAS 6860- or Brake Charger/Bleeder Unit -VAS
5234- (example illustration).
– Use the Piston Resetting Tool -T10145- to press the brake
caliper piston completely back into the brake caliper.
– Clean the brake caliper at the contact surfaces -arrows- for
the brake pad retaining plates. 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.

90 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Clip the brake pad retaining plates -1- and the brake pad
spring -2- into the brake caliper.

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

– If equipped, remove the protective film from the backing

plate of the brake pad.
– If re-using, install the marked brake pads in the same loca‐
tion.
– Insert the brake pads -3 and 4- one after the other into the
brake caliper by pressing each brake pad against the brake
pad springs and pushing them all the way onto the brake
pad retaining plates.
– Install the brake pad wear sensor. Refer to ⇒ P2.8 ad Wear
Indicator Wire, Removing and Installing”, page 123 .
– Install the brake caliper. Refer to ⇒ C2.3.2 aliper, Removing
and Installing, Six-Piston Steel Brake”, page 101 .
– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
– Check brake fluid level, and fill if necessary.

2. Front Brakes 91
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1.4 Six-Piston Steel Brakes”, page 69

2.2.4 Brake Pads, Removing and Installing,

Six-Piston Ceramic Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required
♦ Piston Resetting Tool -T10145-

♦ Hook Tool -T40207-

♦ Commercial type punch pin

Removing
• Label the brake pads when removing if they are going to
be used again. Install in the same position, otherwise the
braking effect will be uneven.
– Remove the affected front wheel, while observing the safe‐
ty precautions for vehicles equipped
Protectedwith ceramic
by copyright. brakes.
Copying for private or commercial purposes, in part or in whole, is not
Refer to ⇒ Suspension, Wheelspermitted
and Steering; Rep. Gr. 44;
unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability

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

– Disengage balance springs -2-, by using the Hook Tool

-T40207- to push downward -arrow- and disengage on the
brake pad pin -3-.

92 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

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.

– Disengage and remove the balance springs from the brake

pads -1-.
– Disconnect the brake pad wear sensor connector -1-.

– Open the protective cap -2-, free up the wire and unclip at
the brake caliper and the brake pad spring -arrows-.
TIP:

2. Front Brakes 93
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Pushing back on the brake pads lightly with suitable pliers

-1- makes it easier to remove the brake pads -2- from the
brake caliper.
♦ To prevent damage to the paint coat on the brake caliper,
place a piece of rubber between the pliers and brake caliper.
– Remove the bolt -3-.

CAUTION
There is a risk of injury by the tensioned brake pad spring
jumping out.
– Use a hand to press down on the brake pad spring when
removing the brake pad pin.

– Press down the brake pad spring -2- -arrows-, then remove
the brake pad pin -1- from the brake caliper.
– Remove the brake pad spring.
– Remove the brake pads -1 and 2- from the brake caliper.

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.

TIP:
For brake pads that are being reused, pay attention to the brake
pad wear sensor -3-.
Installing
Install in the reverse order of removal while noting the following:

94 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Check the wear specification of the brake rotors. Refer to ⇒

R5.4.2 otors, Checking, Ceramic Brakes”, page 16 .
• Always replace brake pads on both sides of the axle.
• Use the complete repair kit when installing new brake pads.
• Components to be used when installing new brake pads.
Refer to ⇒ Electronic Parts Catalog (ETKA).

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

• Do not clean ceramic brake rotors with fluids.
• Check the protective caps of the brake caliper pistons for
damage and install the complete repair kit, if necessary.
Refer to ⇒ C2.2.3 aliper Piston, Removing and Installing,
Six-Piston Brake”, page 178 .

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Check the brake fluid level before pushing the brake cali‐
per piston back into the brake cylinders.

– If the brake fluid is up to the “MAX” marking on used brake

pads, it must be extracted.
– Evacuate theProtected
brake by fluid -2- in
copyright. the brake
Copying for privatefluid reservoir
or commercial within part or in whole, is not
purposes,
the screen installed
permitted -1-,
unlessusing the
authorised by Brake
AUDI AG.Filling
AUDI AGand Bleeding
does not guarantee or accept any liability
Equipment -VAS with6860- ortheBrake
respect to Charger/Bleeder
correctness Unit -VAS
of information in this document. Copyright by AUDI AG.
5234- (example illustration).
– Use the Piston Resetting Tool -T10145- to press the brake
caliper piston completely back into the brake caliper.
– Clean the retaining pin -arrows- on the brake caliper on the
contact surface to the brake pads.

2. Front Brakes 95
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– With used brake pads check the wire -3- for the brake pad
wear sensor is seated correctly and for damage.

• If the brake pad wear sensor is damaged, replace the 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
– Insertwithbrake pads -1 and 2- into the brake caliper.
respect to the correctness of information in this document. Copyright by AUDI AG.

– Note the installation position of the brake pad spring:

96 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• Left side: the bracket -arrow- for the brake pad wear sensor,
faces upward.
• Right side: the bracket -arrow- for the brake pad wear sen‐
sor, faces downward.
– With used brake pads, clean the brake pad pin -1- and thinly
coat with Grease.

– Bring brake pad spring -2- into its installed location, and
press down -arrows-. 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
– Insert the brake pad pin and fasten with
with respect thecorrectness
to the bolt -3-.of information in this document. Copyright by AUDI AG.
– Install the brake pad wear sensor. Refer to ⇒ P2.8.2 ad
Wear Indicator Wire, Removing and Installing, Six-Piston
Ceramic Brake”, page 125 .
– Engage the balance springs -2- in the brake pad -1-.

2. Front Brakes 97
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Engage the balance springs on the brake
permitted pad pinby-3-,
unless authorised AUDI byAG. AUDI AG does not guarantee or accept any liability
pushing with the Hook Tool -T40207- downward
with respect -arrow-.
to the correctness of information in this document. Copyright by AUDI AG.

– Install the front wheel, while observing the safety precau‐

tions for vehicles with ceramic brakes. Refer to ⇒ Suspen‐
sion, Wheels and Steering; Rep. Gr. 44; Wheels, Tires.
– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
– Check brake fluid level, and fill if necessary.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1.5 Six-Piston Ceramic Brake”, page 72

2.3 Brake Caliper, Removing and Installing

⇒ C2.3.1 aliper, Removing and Installing, Single and Dual-Pis‐
ton Brakes”, page 98
⇒ C2.3.2 aliper, Removing and Installing, Six-Piston Steel
Brake”, page 101
⇒ C2.3.3 aliper, Removing and Installing, Six-Piston Ceramic
Brake”, page 103

2.3.1 Brake Caliper, Removing and Instal‐

ling, Single and Dual-Piston Brakes
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
In the following description the brake caliper is removed with the
brake carrier and brake pads. The brake hose remains connec‐
ted.
Removing
– Remove the affected front wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.

98 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Disconnect the connector -arrow- for the brake pad wear

indicator contact from the right brake caliper.

• For easier removal of the brake caliper from the brake pad,
push the brake pads -3- back lightly with suitable pliers -1-
as shown (example illustration).

• To prevent damage to the surface on the brake caliper,

place a piece of rubber -2- or similar between the pliers and
brake caliper.
– Remove the bolts -arrows- and carefully remove the brake
caliper with the brake carrier and the installed brake pads
from the brake rotor.

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 99
 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
There is a risk of damaging the brake hose due to the weight
of the brake caliper.
– Never let the brake caliper hang on the brake hose.

– Hang the brake caliper using a suitable wire.

NOTICE
There is a risk of damaging the brake caliper piston if handled
incorrectly. Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Never activate the brakes if the brake caliper is removed.
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
Install in the reverse order of removal while noting the following:

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

– Carefully slide the brake caliper with the brake carrier and
the installed brake pads over the brake rotor.

– Tighten the bolt -arrows- to the tightening specification.

• Make sure the brake hose is routed correctly.
• Make sure the brake hose is not pinched, bent, twisted or
rubbing against the vehicle.
– Connect the connector -arrow- for the brake pad wear indi‐
cator contact on the right brake caliper.

100 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
– Check brake fluid level, and fill if necessary.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly
Protected by before
copyright. Copying for driving
private or commercial purposes, in part or in whole, is not
the vehicle for the first time. 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.

Tightening Specifications
♦ Refer to ⇒ -2.1 Front Brakes”, page 61
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

2.3.2 Brake Caliper, Removing and Instal‐

ling, Six-Piston Steel Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
In the following description the brake caliper is removed with the
brake pads. The brake hose remains connected.
Removing
– Remove the front wheel. Refer to ⇒ Suspension, Wheels,
Steering; Rep. Gr. 44; Wheels, Tires.
– Disconnect the connector -1- for the Right Front Brake Pad
Wear Sensor -G35- on the right brake caliper.

• Pushing the brake pads -3- slightly into the brake caliper
using suitable pliers -1- makes it easier to remove the brake
caliper from the brake rotor.

2. Front Brakes 101

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• To prevent damage to the paint coat on the brake caliper,

place a piece of rubber -2- between the pliers and brake
caliper.

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

– Remove the bolts -arrows-.

– Carefully remove the brake caliper with the brake pads from
the brake rotor.

NOTICE
There is a risk of damaging the brake hose due to the weight
of the brake caliper.
– Never let the brake caliper hang on the brake hose.

– Hang the brake caliper using a suitable wire.

NOTICE
There is a risk of damaging the brake caliper piston if handled
incorrectly.
– Never activate the brakes if the brake caliper is removed.

Installing
Install in the reverse order of removal while noting the following:

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

102 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Carefully slide the brake caliper with the installed brake pads
over the brake rotor while paying attention to the brake hose.

– Tighten the bolts -arrows-.

• Make sure the brake hose is routed correctly.
• Make sure the brake hose is not pinched, bent, twisted or
rubbing against the vehicle.
– Connect the connector -1-.

– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
– Check brake fluid level, and fill if necessary.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1.4 Six-Piston Steel Brakes”, page 69
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

2.3.3 Brake Caliper, Removing and Instal‐

ling, Six-Piston Ceramic Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

page 9 .
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.

In the following description the brake caliper is removed with the

brake pads. The brake hose remains connected.

2. Front Brakes 103

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Removing
– Remove the front wheel, while observing the safety precau‐
tions for ceramic brakes. Refer to ⇒ Suspension, Wheels
and Steering; Rep. Gr. 44; Wheels, Tires.
TIP:

♦ For easier removal of the brake caliper from the brake rotor,
push the brake pads -2- back lightly with suitable pliers -1-.
♦ To prevent damage to the paint coat on the brake caliper,
place a piece of rubber between the pliers and brake caliper.
– Disconnect the brake pad wear sensor connector -1-.

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

– Remove the bolts -arrows-.

– Carefully remove the brake caliper with the brake pads from
the brake rotor.

NOTICE
There is a risk of damaging the brake hose due to the weight
of the brake caliper.
– Never let the brake caliper hang on the brake hose.

– Hang the brake caliper using a suitable wire.

104 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
There is a risk of damaging the brake caliper piston if handled
incorrectly.
– Never activate the brakes if the brake caliper is removed.

Installing
Install in the reverse order of removal while noting the following:

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

– Slide the brake caliper with the brake pads installed carefully
over the brake rotor.

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.

– Tighten the bolts -arrows-.

• Make sure the brake hose is routed correctly.
• Make sure the brake hose is not pinched, bent, twisted or
rubbing against the vehicle.
– Connect the brake pad wear sensor connector -1-.
– Install the front wheel, while observing the safety precau‐
tions for ceramic brakes. Refer to ⇒ Suspension, Wheels
and Steering; Rep. Gr. 44; Wheels, Tires.
– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
– Check brake fluid level, and fill if necessary.

2. Front Brakes 105

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1.5 Six-Piston Ceramic Brake”, page 72

2.4 Brake Caliper, Replacing

⇒ C2.4.1 aliper, Replacing, Single and Dual-Piston Brakes”,
page 106
⇒ C2.4.2 aliper, Replacing, Six-Piston Steel Brake”, page 110
⇒ C2.4.3 aliper, Replacing, Six-Piston Ceramic Brake”, page
114

2.4.1 Brake Caliper, Replacing, Single and

Dual-Piston Brakes
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
The brake caliper is removed and disconnected from the hy‐
draulic system in the following description. The brake hose is
removed.
Special tools and workshop equipment required 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
♦ Brake Pedal Actuator -V.A.G 1869/2-. with respect to the correctness of information in this document. Copyright by AUDI AG.

106 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or

Brake Charger/Bleeder Unit -VAS 5234-

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.

♦ Wrench - Brake Bleeder Set -VAS 5519-

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

2. Front Brakes 107

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Plugs from the Assembly Part Set -5Q0 698 311-: M10
-item 1- and M12 -item 2-

♦ Safety Gloves
Removing

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.

– Insert the Brake Pedal Actuator -V.A.G 1869/2- -item A- be‐

tween the brake pedal and driver seat. Pretension the brake
pedal at least 60 mm. (By doing this, the valves in the brake
master cylinder are closed and the brake fluid reservoir does
not run empty.)
– Remove the affected front wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– Remove the protective cap from the bleed screw on the left
front caliper.

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

108 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Connect the hose -1- on the collector bottle (example illus‐

tration).
– Open the bleed screw to reduce the pressure in the hydraul‐
ic system.
– Close the bleed screw and remove the collection bottle.
• Do not remove the Brake Pedal Actuator -V.A.G 1869/2-.
– To protect against escaping brake fluid, place a cloth under
the separating point.

CAUTION
Risk of accident due to the brakes malfunctioning.
– Brake fluid must never come into contact with fluids con‐
taining mineral oils (oil, gasoline, cleaning solutions).
– Wear safety gloves that are free of oil and grease.

– Remove the banjo bolt -arrow- and remove the brake hose
from the brake caliper (example 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.

– Immediately close open connection points with a clean plug.

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Rinse off any leaking brake fluid immediately using plenty
of water.

– Remove the brake pads. Refer to ⇒ P2.2 ads, Removing

and Installing”, page 75 .
Installing
Install in the reverse order of removal while noting the following:
– Install the brake pads. Refer to ⇒ P2.2 ads, Removing and
Installing”, page 75 .
– Install the banjo bolt -arrow- in the brake caliper and tighten
to the required tightening specification (example illustration).

2. Front Brakes 109

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• Make sure the brake hose is routed correctly.

• Make sure the brake hose is not pinched, bent, twisted or
rubbing against the vehicle.
– Remove the Brake Pedal Actuator -V.A.G 1869/2-.
– Only bleed the brakes on the wheel from which the brake
caliper and the brake hose were loosened. Refer to ⇒
S5.2 ystem, Bleeding”, page 208 .
• If the brake pedal still feels “soft”, completely bleed the
brakes. Refer to ⇒ S5.2 ystem, Bleeding”, page 208 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1 Front Brakes”, page 61
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

2.4.2 Brake Caliper, Replacing, Six-Piston

Steel Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
The brake caliper is removed and disconnected from the hy‐
draulic system in the following description. The brake hose is
removed.
Special tools and workshop equipment required
♦ Brake Pedal Actuator -V.A.G 1869/2-.

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

110 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or

Brake Charger/Bleeder Unit -VAS 5234-

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

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
♦ Plugs from the Assembly Part Set -5Q0 698 311-:
with M10
respect to the correctness of information in this document. Copyright by AUDI AG.
-item 1- and M12 -item 2-

♦ Safety Gloves

2. Front Brakes 111

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Removing

– Insert the Brake Pedal Actuator -V.A.G 1869/2- -item A- be‐

tween the brake pedal and driver seat. Pretension the brake
pedal at least 60 mm. (By doing this, the valves in the brake
master cylinder are closed and the brake fluid reservoir does
not run empty.)
– Remove the affected front wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.

– Remove the protective cap -3- from the bleed screw -1- on
the brake caliper.

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Connect the collection bottle
permitted hose
unless -2-. by AUDI AG. AUDI AG does not guarantee or accept any liability
authorised
with respect to the correctness of information in this document. Copyright by AUDI AG.
– Open the bleed screw to reduce the pressure in the hydraul‐
ic system.
– Close the bleed screw and remove the collection bottle.
• Do not remove the Brake Pedal Actuator -V.A.G 1869/2-.
– To protect against escaping brake fluid, place a cloth under
the separating point.

112 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Risk of accident due to the brakes malfunctioning.
– Brake fluid must never come into contact with fluids con‐
taining mineral oils (oil, gasoline, cleaning solutions).
– Wear safety
Protected gloves
by copyright. thatforare
Copying free
private of oil and
or commercial grease.
purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
– Remove the union bolt -arrow- and move the brake hose to
the side.
– Immediately close open connection points with a clean plug.

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Rinse off any leaking brake fluid immediately using plenty
of water.

– Remove the brake pads. Refer to ⇒ P2.2.3 ads, Removing

and Installing, Six-Piston Steel Brake”, page 88 .
Installing
Install in the reverse order of removal while noting the following:
– Install the brake pads. Refer to ⇒ P2.2.3 ads, Removing and
Installing, Six-Piston Steel Brake”, page 88 .
– Tighten the union bolt -arrow-.

• Make sure the brake hose is routed correctly.

• Make sure the brake hose is not pinched, bent, twisted or
rubbing against the vehicle.
– Remove the Brake Pedal Actuator -V.A.G 1869/2-.

2. Front Brakes 113

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Only bleed the brakes on the wheel from which the brake
caliper and the brake hose were loosened. Refer to ⇒
S5.2 ystem, Bleeding”, page 208 .
• If the brake pedal still feels “soft”, completely bleed the
brakes. Refer to ⇒ S5.2 ystem, Bleeding”, page 208 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1.4 Six-Piston Steel Brakes”, page 69
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44; unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
permitted
Wheels, Tires. with respect to the correctness of information in this document. Copyright by AUDI AG.

2.4.3 Brake Caliper, Replacing, Six-Piston

Ceramic Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
The brake caliper is removed and disconnected from the hy‐
draulic system in the following description. The brake hose is
removed.
Special tools and workshop equipment required
♦ Brake Pedal Actuator -V.A.G 1869/2-.

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or

Brake Charger/Bleeder Unit -VAS 5234-

114 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

♦ Plugs from the Assembly Part Set -5Q0 698 311-: M10
-item 1- and M12 -item 2-

Removing

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.

– Insert the Brake Pedal Actuator -V.A.G 1869/2- -item A- be‐

tween the brake pedal and driver seat. Pretension the brake
pedal at least 60 mm. (By doing this, the valves in the brake
master cylinder are closed and the brake fluid reservoir does
not run empty.)
– Remove the respective front wheel, while observing the
safety precautions for ceramic brakes. Refer to ⇒ Suspen‐
sion, Wheels and Steering; Rep. Gr. 44; Wheels, Tires.
– Remove the protective cap -3- from the bleed screw -1-.

2. Front Brakes 115

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

– Connect the collection bottle hose -1-.

– Open the bleed screw to reduce the pressure in the hydraul‐
ic system.
– Close the bleed screw and remove the collection bottle.
• Do not remove the Brake Pedal Actuator -V.A.G
Protected 1869/2-.
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
– To protect against escaping brake fluid, place
witharespect
clothtounder
the correctness of information in this document. Copyright by AUDI AG.
the separating point.

CAUTION
Risk of accident due to the brakes malfunctioning.
– Brake fluid must never come into contact with fluids con‐
taining mineral oils (oil, gasoline, cleaning solutions).
– Wear safety gloves that are free of oil and grease.

– Remove the union bolt -1- and bolt -2-.

– Remove the bracket.

– Immediately close open connection points with a clean plug.

116 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Rinse off any leaking brake fluid immediately using plenty
of water.

TIP:

♦ For easier removal of the brake caliper from the brake rotor,
push the brake pads -2- back lightly with suitable pliers -1-.
♦ To prevent damage to the paint coat on the brake caliper,
place a piece of rubber between the pliers and brake caliper.
– Seal the open connection on the brake caliper immediately
with plugs.
– Disconnect the brake pad wear sensor connector -1-.

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

– Unscrew the bolts -arrows- and carefully remove the brake

caliper with the brake pads from the brake rotor.
– If necessary, remove the brake pads. Refer to ⇒ P2.2.4 ads,
Removing and Installing, Six-Piston Ceramic Brake”, page
92 .
Installing
Install in the reverse order of removal while noting the following:
– Bring the brake caliper into its installed position and tighten
the bolts -arrows-.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Install the brake pads. Refer to ⇒ P2.2.4 ads, Removing and

Installing, Six-Piston Ceramic Brake”, page 92 .
– Bring the bracket into the installation position and tighten the
bolt -2-.

– Fasten the brake hose -1- to the brake caliper.

• Make sure the brake hose is routed correctly.
• Make sure the brake hose is not blocked, bent, twisted or
rubbing against the vehicle.
– Remove the Brake Pedal Actuator -V.A.G 1869/2-.
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
– Only bleed the brakes on the wheel from which the
with brake
respect to the correctness of information in this document. Copyright by AUDI AG.
caliper and the brake hose were loosened. Refer to ⇒
S5.2 ystem, Bleeding”, page 208 .
• If the brake pedal still feels “soft”, completely bleed the
brakes. Refer to ⇒ S5.2 ystem, Bleeding”, page 208 .
– Install the front wheel, while observing the safety precau‐
tions for ceramic brakes. Refer to ⇒ Suspension, Wheels
and Steering; Rep. Gr. 44; Wheels, Tires.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

118 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Tightening Specifications
♦ Refer to ⇒ -2.1.5 Six-Piston Ceramic Brake”, page 72

2.5 Brake Carrier, Removing and Installing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the brake pads. Refer to ⇒ P2.2 ads, Removing
and Installing”, page 75 .
– Remove the bolts -arrows- and remove the brake carrier -1-.

Installing
Install in the reverse order of removal while noting the following:

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

– Install the bolts -arrows- for the brake carrier and tighten to
the required tightening specification.

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 the brake pads. Refer to ⇒ P2.2 ads, Removing and

Installing”, page 75 .

2. Front Brakes 119

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
Tightening Specifications
♦ Refer to ⇒ -2.1 Front Brakes”, page 61

2.6 Brake Rotor, Removing and Installing

⇒ R2.6.1 otor, Removing and Installing, Steel Brakes”, page
120
⇒ R2.6.2 otor, Removing and Installing, Ceramic Brakes”, page
121

2.6.1 Brake Rotor, Removing and Installing,

Steel Brakes
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the brake caliper. Refer to ⇒ C2.3 aliper, Removing
and Installing”, page 98 .
– Single and dual-piston brakes: remove the brake carrier. Re‐
fer to ⇒ C2.5 arrier, Removing and Installing”, page 119 .
– Remove the bolt -arrow- and remove the brake rotor.

• Do not loosen the brake rotor from the hub by prying.

• Do not remove the brake rotor from the hub with a hammer.
• If the connection cannot be separated, use rust remover.
Installing
Install in the reverse order of removal while noting the following:
– Check the brake rotors for wear and damage before reusing
them. ReferProtected
to ⇒ R5.4 otor,Copying
by copyright. Checking”,
for privatepage 13 . purposes, in part or in whole, is not
or commercial
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
– Thoroughly clean the brake
with respect rotor and
to the correctness hub contact
of information surfaces
in this document. Copyright by AUDI AG.
and clear them of corrosion.
– Place the brake rotor on the wheel hub.

120 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• Do not tilt the brake rotor when mounting it on the wheel

hub.
– Tighten the bolt -arrow- to the tightening specification.

– Install the brake carrier. Refer to ⇒ C2.5 arrier, Removing

and Installing”, page 119 .
– Install the brake caliper. Refer to ⇒ C2.3 aliper, Removing
and Installing”, page 98 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1 Front Brakes”, page 61
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
2.6.2 Brake Rotor, Removing and
permitted Installing,
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.
Ceramic Brakes
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the brake caliper. Refer to ⇒ C2.3.3 aliper, Remov‐
ing and Installing, Six-Piston Ceramic Brake”, page 103 .
– Remove the bolt -1- and remove the brake rotor by hand. Do
not use any tools.

• Do not drop the brake rotor.

• Do not loosen the brake rotor from the hub by prying.
• Do not remove the brake rotor from the hub with a hammer.

2. Front Brakes 121

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• If the connection cannot be separated, use rust remover.

If the brake rotor is seized, do the following:
– Install two M8 bolts -arrows- all the way into the threaded
holes of the brake rotor.
– Tighten the bolts 1/2 turn farther alternating from side to side
to loosen the brake rotor from the wheel hub.
Installing
Install in the reverse order of removal while noting the following:
– Before reusing ceramic brake rotors check for wear and
damage. Refer to ⇒ R5.4.2 otors, Checking, Ceramic
Brakes”, page 16 .
– Thoroughly clean the brake rotor and hub contact surfaces
and clear them of corrosion.
– Place the brake rotor on the wheel hub.
• Do not tilt the brake rotor when mounting it on the wheel
hub.
– Tighten the bolt -arrow- to the tightening specification.

– Install the brake caliper. Refer to ⇒ C2.3.3 aliper, Removing

and Installing, Six-Piston Ceramic Brake”, page 103 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1.5 Six-Piston Ceramic Brake”, page 72

2.7 Brake Shield, Removing and Installing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the affected brake rotor. Refer to Protected
⇒ R2.6byotor, Re‐
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
moving and Installing”, page 120 . with respect to the correctness of information in this document. Copyright by AUDI AG.

– Remove the bolts -arrows-.

122 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the brake shield -1-. There are different versions.

Installing
Install in the reverse order of removal while noting the following:
– Clean the contact surfaces on the brake shield and wheel
hub.
– Install the brake rotor. Refer to ⇒ R2.6 otor, Removing and
Installing”, page 120 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1 Front Brakes”, page 61

2.8 Brake Pad Wear Indicator Wire, Re‐

moving and Installing
⇒ P2.8.1 ad Wear Indicator Wire, Removing and Installing, Six-
Piston Steel Brake”, page 123
⇒ P2.8.2 ad Wear Indicator Wire, Removing and Installing, Six-
Piston Ceramic Brake”, page 125

2.8.1 Brake Pad Wear Indicator Wire, Re‐

moving and Installing, Six-Piston Steel
Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the right front wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– Disconnect the connector -1-.

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

2. Front Brakes 123

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Free up the wire by opening the protective cap -2- and dis‐
engage the wire from the brake caliper.
– Pull the Right Front Brake Pad Wear Sensor -G35- out of the
brake pad, while doing so, pay attention to the clip -2-.

Installing

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.

TIP:
If the clip -2- goes missing, the brake pad wear indicator wire
must be replaced.
– Insert the Right Front Brake Pad Wear Sensor -G35- togeth‐
er with the clip into the brake pads until it engages.
– Secure the brake pad wear indicator wire back into the same
position.
– Connect the connector -1-.

124 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Tightening Specifications
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

2.8.2 Brake Pad Wear Indicator Wire, Re‐

moving and Installing, Six-Piston Ce‐
ramic Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the respective front wheel, while observing the
safety precautions for ceramic brakes. Refer to ⇒ Suspen‐
sion, Wheels and Steering; Rep. Gr. 44; Wheels, Tires.
– Disconnect the brake pad wear sensor connector -1-.

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

– Open the protective cap -2-, free up the wire and unclip at
the brake caliper and the brake pad spring -arrows-.
– Remove the break pad wear sensor -3- from the brake pad,
while being careful of the clamps -4-.

2. Front Brakes 125

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Installing

TIP: Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
If the clip -4- goes missing, the brake pad wear indicator wire
with respect to the correctness of information in this document. Copyright by AUDI AG.
must be replaced.
– Insert the brake pad wear sensor -3- with the retainer until it
engages in the brake pad.
– Secure the brake pad wear indicator wire back into the same
positions.
– Connect the connector -1-.
– Install the front wheel, while observing the safety precau‐
tions for ceramic brakes. Refer to ⇒ Suspension, Wheels
and Steering; Rep. Gr. 44; Wheels, Tires.

126 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

3 Rear Brakes
⇒ -3.1 Rear Brakes”, page 127
⇒ P3.2 ads, Removing and Installing”, page 130
⇒ C3.3 aliper, Removing and Installing”, page 138
⇒ C3.4 aliper, Replacing”, page 140
Protected⇒byC3.5 arrier,
copyright. CopyingRemoving and Installing”,
for private or commercial purposes, inpage 145
part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
⇒ R3.6
with respect otor,
to the Removing
correctness andin Installing”,
of information page 146
this document. Copyright by AUDI AG.

⇒ S3.7 hield, Removing and Installing”, page 147

3.1 Overview - Rear Brakes

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

3. Rear Brakes 127

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Line
❑ 14 Nm
2 - Bracket
❑ For the brake line/hose
❑ On the body
3 - Brake Hose
❑ Make sure it is in the
installation position
4 - Spring
❑ Replace if damaged
5 - Protective Cap
6 - Bleed Screw
❑ 11 Nm
7 - Seal
❑ Replace after removing
8 - Bolt 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
❑ 8 Nm with respect to the correctness of information in this document. Copyright by AUDI AG.
9 - Parking Brake Motor
❑ Refer to ⇒ -4.1 Parking
Brake”, page 149
10 - Cap
❑ For the guide pins
11 - Guide Pin
❑ 35 Nm
12 - Spring
❑ Replace if damaged
13 - Bolt
❑ Vehicle with torsion
beam axle. Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 42; Wheel Bearing, Trailing Arm;
Overview - Wheel Bearing.
❑ Vehicles with multi-link suspension: 12 Nm
14 - Wheel Bearing Housing
15 - Bolt
❑ Replace after removing
❑ 90 Nm + 90°
16 - Brake Shield
❑ Refer to ⇒ S3.7 hield, Removing and Installing”, page 147
17 - Brake Rotor
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Refer to ⇒ R5.4 otor, Checking”, page 13
❑ Wear limit specified on the brake rotor
❑ Always replace on both sides of the axle. Replace the brake pads as well.
❑ Refer to ⇒ R3.6 otor, Removing and Installing”, page 146
18 - Bolt
❑ 8 Nm
19 - Brake Carrier

128 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

❑ Refer to ⇒ C3.5 arrier, Removing and Installing”, page 145

20 - Spring
❑ Replace if damaged
21 - Outer Brake Pad
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Checking the brake pads, wear limit. Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900; Maintenance Procedures; Brake Pad
Thickness, Checking.
❑ Always replace on both sides of the axle.
❑ Refer to ⇒ P3.2 ads, Removing and Installing”, page 130
❑ Refer to ⇒ Fig. ““Installation position of the brake pads.”“, page 130
22 - Inner Brake Pad
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
❑ Checking the brake pads, wear limit. Refer to ⇒ Maintenance; Booklet 860; Maintenance Procedures;
Brake Pad Thickness, Checking / ⇒ Maintenance; Booklet 900; Maintenance Procedures; Brake Pad
Thickness, Checking.
❑ Always replace on both sides of the axle.
❑ Refer to ⇒ P3.2 ads, Removing and Installing”, page 130
❑ Refer to ⇒ Fig. ““Installation position of the brake pads.”“, page 130
23 - Spring
24 - Brake Caliper
❑ Allocation. Refer to the ⇒ Electronic Parts Catalog (ETKA).
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 the brake hose when changing the brake pads.
with respect to the correctness of information in this document. Copyright by AUDI AG.

❑ Installation Position
♦ Refer to ⇒ Fig. ““Torsion Beam Axle Brake Caliper Installation Position”“, page 129
♦ Refer to ⇒ Fig. ““Multi-Link Suspension Installation Position”“, page 130
❑ Refer to ⇒ C3.3 aliper, Removing and Installing”, page 138
❑ Refer to ⇒ C3.4 aliper, Replacing”, page 140
25 - Banjo Bolt
❑ Permanent with seals
❑ Clean any corrosion from the sealing surface on the brake caliper
❑ If damaged, replace the brake hose
❑ 35 Nm

Torsion Beam Axle Brake Caliper Installation Position

1 - Brake Caliper
A - Torsion Beam Axle

3. Rear Brakes 129

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Brake System - Edition 01.2023

Multi-Link Suspension Installation Position

1 - Brake Caliper
B - Multi-Link Suspension
Installation position of the brake pads.

A - Inner Brake Pad on Piston Side

B - Outer Brake Pad
• Make sure that the spring sits in the backing plate on the
inner brake pad.

3.2 Brake Pads, Removing and Installing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Vehicle Diagnostic Tester 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.

130 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Torque Wrench 1331 Insert - Ratchet Head -VAS 6784-

♦ Piston Resetting Tool -T10145-

♦ Hex Bit - 7mm -T10503-

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.

♦ Grease. Refer to the ⇒ Electronic Parts Catalog (ETKA).

Removing
• Label the brake pads when removing if they are going to
be used again. Install in the same position, otherwise the
braking effect will be uneven.
• Do not disconnect the connectors from the parking brake
motors.
– Release the parking brake.
– Switch off the ignition.
– Remove the affected rear wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– To replace the brake pads, drive the parking brake motors
rearward using the program “brake pads, removing”. Refer
to ⇒ E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.

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– Disconnect the connector -2- from the Right Rear ABS

Wheel Speed Sensor -G44-/ Left Rear ABS Wheel Speed
Sensor -G46- and free up the wire. (Shown on an FWD
vehicle).

– If installed, disconnect and free up the connector -2- for the

brake pad wear sensor by opening the dust cap -1-.

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

CAUTION
There is a risk of injury because the spring is tensioned.
The spring can jump out and cause eye or skin injury.
– Hold the spring with a hand.

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Brake System - Edition 01.2023

– Pry out the spring -4- for the brake pads -2- on the brake
caliper -1- and on the brake carrier to do so lift the lever out
of the guide -arrow- on the brake caliper.
– Remove the caps -arrows- from the guide pins.

– Remove both guide pins from the brake caliper using the
Hex Bit - 7mm -T10503- and Torque Wrench 1331 Insert -
Ratchet Head -VAS 6784-.

NOTICE
There is a risk of damaging the brake hose due to the weight
of the brake caliper.
– Never let the brake caliper hang on the brake hose.

– Hang the brake caliper -1- using suitable wire -A-.

– Remove the brake pads -2 and 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.

3. Rear Brakes 133

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

NOTICE
There is a risk of damaging the brake caliper piston if handled
incorrectly.
– Never activate the brakes if the brake caliper is removed.

Installing
Install in the reverse order of removal while noting the following:
– Check the brake rotors for wear and damage. Refer to ⇒
R5.4 otor, Checking”, page 13 .
• Use the complete repair kit when installing new brake pads.
• Components to be used when installing new brake pads.
Refer to ⇒ Electronic Parts Catalog (ETKA).

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Use only mineral spirits to clean the brake caliper.

• Check the protective caps of the brake caliper pistons for
damage and install the complete repair kit, if necessary. Re‐
fer to ⇒ C3.2 ap, Removing and Installing”, page 183 .
• Check the bearing bushings of the guide pins for damage
and check that the guide pins move easily. Install the com‐
plete repair kit, if necessary. Refer to ⇒ B3.3 ushing and
Guide Pin, Replacing”, page 186 .

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.

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Check the brake fluid level before pushing the brake cali‐
per piston back into the brake cylinders.

– If the brake fluid is up to the “MAX” marking on used brake

pads, it must be extracted.
– Evacuate the brake fluid -2- in the brake fluid reservoir with
the screen installed -1-, using the Brake Filling and Bleeding
Equipment -VAS 6860- or Brake Charger/Bleeder Unit -VAS
5234- (example illustration).

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Brake System - Edition 01.2023

NOTICE
Improper handling increases the risk of destroying the brake
caliper.
– Never reset the pistons manually.

– Use the Piston Resetting Tool -T10145- -item 1- to com‐

pletely press back the brake caliper piston -2-.
– Clean the brake carrier on the contact surface -1 and 2- for
the brake carrier and coat thinly with Grease.

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

– If equipped, remove the protective film from the backing

plate of the brake pad.
– If re-using, install the marked brake pads in the same loca‐
tion.
– Insert the brake pads into the brake carrier, while paying
attention to the installation position. Refer to ⇒ Fig. ““Installa‐
tion position of the brake pads.”“, page 130 .
– Position the retaining plate -2- as shown on the top and
bottom on the brake pads -1 and 3-.

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Brake System - Edition 01.2023

– Pay attention that the retaining plate is seated correctly

-arrows-.
– Position the brake pads together with the retaining plate
inside and outside.
– Pay attention that the spring -5- is seated on the inner brake
pad.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Insert the brake caliper. 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 both guide pin using the Hex Bit - 7mm -T10503- and
Torque Wrench 1331 Insert - Ratchet Head -VAS 6784- and
tighten to the required tightening specification.

– Install the caps -arrows-.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– If installed, connect the brake pad wear sensor connector -2-

and secure the wire using the dust cap -1-.

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

– Position the brake caliper -1-.

• The spring -4- must sit on the brake carrier -3- as shown.
– Pay attention that the spring -4- is seated as shown in the
guide -arrow- on the brake caliper -1-.
– Complete the program "Brake Pads, Removing” using the
⇒ Vehicle diagnostic tester.
– With the vehicle stationary, firmly press the brake pedal sev‐
eral times so that the brake pads in the operating condition
properly sit in their respective position.
– Check brake fluid level, and fill if necessary.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -3.1 Rear Brakes”, page 127
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

3.3 Brake Caliper, Removing and Installing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
In the following description the brake caliper is removed with the
brake carrier and brake pads. The brake hose remains connec‐
ted.
Special tools and workshop equipment required
♦ Multipoint Socket -T10035-

Removing
• Do not disconnect the connectors from the parking brake
motors.
– Release the parking brake.
– Switch off the ignition.
– Remove the affected rear wheel. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– If installed, disconnect the brake pad wear sensor connector
-2-.

– Disconnect the connector -2- from the Right Rear ABS

Wheel Speed Sensor -G44-/ Left Rear ABS Wheel Speed
Sensor -G46- and free up the wire. (Shown on an FWD
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.

138 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the brake carrier bolts -arrows- using the Multipoint

Socket -T10035-.
– Remove the brake caliper with the brake carrier and installed
brake pads from the brake rotor.
• If the brake rotor is so worn that the brake caliper cannot be
removed, then the parking brake must be driven back. Refer
to ⇒ page 21 .

NOTICE
There is a risk of damaging the brake hose due to the weight
of the brake caliper.
– Never let the brake caliper hang on the brake hose.

– Hang the brake caliper using a suitable wire.

NOTICE
There is a risk of damaging the brake caliper piston if handled
incorrectly.
– Never operate the brakes and electromechanical parking
brake if the brake caliper is removed.

Installing
Install in the reverse order of removal while noting the following:

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments mayCopying
Protected by copyright. occur. 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
Never blow
respect to theout the brake
correctness system
of information in thiswith compressed
document. air.AG.
Copyright by AUDI

• Use only mineral spirits to clean the brake caliper.

– Carefully slide the brake caliper with the brake carrier and
the installed brake pads over the brake rotor.
– Install the bolts -arrows- for the brake carrier and tighten to
the required tightening specification.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Connect the connector -1-.

• Make sure that the wire and brake hose are routed correctly.
• Make sure the brake hose is not pinched, bent, twisted or
rubbing against the vehicle.
– If installed, disconnect the brake pad wear sensor connector
-2-.

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.

– Drive out the parking brake motor using the ⇒ Vehicle diag‐
nostic tester.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -3.1 Rear Brakes”, page 127
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

3.4 Brake Caliper, Replacing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
The brake caliper is removed and disconnected from the hy‐
draulic system in the following description. The brake hose is
removed.
Special tools and workshop equipment required

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Brake Pedal Actuator -V.A.G 1869/2-.

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or

Brake Charger/Bleeder Unit -VAS 5234-

♦ Wrench - Brake Bleeder Set -VAS 5519-

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 141

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

♦ Plugs from the Assembly Part Set

Protected -5Q0Copying
by copyright. 698 311-: M10
for private or commercial purposes, in part or in whole, is not
-item 1- and M12 -item 2-
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
– Release the parking brake.
– Switch off the ignition.
– Insert the Brake Pedal Actuator -V.A.G 1869/2- -item A- be‐
tween the brake pedal and driver seat. Pretension the brake
pedal at least 60 mm. (By doing this, the valves in the brake
master cylinder are closed and the brake fluid reservoir does
not run empty.)

– Remove the affected rear wheel. Refer to ⇒ Suspension,

Wheels, Steering; Rep. Gr. 44; Wheels, Tires.
– Remove the protective cap from the bleed screw on the left
front caliper.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

– Connect the collection bottle hose -1-.

– Open the bleed screw to reduce the pressure in the brake
system.
– Close thebybleed
Protected screw
copyright. and
Copying remove
for private the collection
or commercial purposes, in bottle.
part or in whole, is not

– Repeat the procedure on ofthe left rear brake caliper.

permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness information in this document. Copyright by AUDI AG.

• Do not remove the Brake Pedal Actuator -V.A.G 1869/2-.

– Remove the bolts -arrows- for the parking brake motor.

– Remove the parking brake motor and set it aside without

disconnecting the connector -1-.

CAUTION
Risk of accident due to the brakes malfunctioning.
– Brake fluid must never come into contact with fluids con‐
taining mineral oils (oil, gasoline, cleaning solutions).
– Wear safety gloves that are free of oil and grease.

– Remove the brake hose banjo bolt -arrow- on the brake

caliper.

3. Rear Brakes 143

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

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.

– Immediately close open connection points with a clean plug.

– Remove the brake pads. Refer to ⇒ P3.2 ads, Removing
and Installing”, page 130 .
Installing
Install in the reverse order of removal while noting the following:
– Install the brake pads. Refer to ⇒ P3.2 ads, Removing and
Installing”, page 130 .
– Rotate the parking brake motor until the bolt and threads are
aligned.
• The parking brake motor must be flush with the brake cali‐
per. Under no circumstances may it be pulled against the
brake caliper with bolts.
– Install the electro-mechanical parking brake motor (refer to
⇒ P4.2 arking Brake MotorV282/Right Parking Brake Mo‐
torV283, Removing and Installing”, page 150 ) and tighten
the bolts to the tightening specification.

– Tighten the brake hose bolt -arrow- on the brake caliper.

• Make sure the brake hose is routed correctly.

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Brake System - Edition 01.2023

• Make sure the brake hose is not pinched, bent, twisted or

rubbing against the vehicle.
– Remove the Brake Pedal Actuator -V.A.G 1869/2-.
– Only bleed the brakes on the wheel from which the brake
caliper and the brake hose were loosened. Refer to ⇒
S5.2 ystem, Bleeding”, page 208 .
• If the brake pedal still feels “soft”, completely bleed the
brakes. Refer to ⇒ S5.2 ystem, Bleeding”, page 208 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -3.1 Rear Brakes”, page 127
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

3.5 Brake Carrier, Removing and Installing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required
♦ Multipoint Socket -T10035-

Removing

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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 the brake pads. Refer to ⇒ P3.2 ads, Removing

and Installing”, page 130 .
– Remove the bolts -arrows- using the Multipoint Socket -
T10035- and remove the brake carrier -1-.

3. Rear Brakes 145

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Installing
Install in the reverse order of removal while noting the following:

WARNING
Health risk due to toxic dust from the brake system.
Irreversible deposit of dust particles in the lungs. Breathing
impairments may occur.
– Never blow out the brake system with compressed air.

• Only use mineral spirits to clean the brake carrier.

– Install the brake pads. Refer to ⇒ P3.2 ads, Removing and
Installing”, page 130 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.
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
Tightening Specifications with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Refer to ⇒ -3.1 Rear Brakes”, page 127

3.6 Brake Rotor, Removing and Installing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the brake caliper. Refer to ⇒ C3.3 aliper, Removing
and Installing”, page 138 .
– Remove the brake carrier. Refer to ⇒ C3.5 arrier, Removing
and Installing”, page 145
– Remove the bolt -arrow- and remove the brake rotor.

• Do not loosen the brake rotor from the hub by prying.

• Do not remove the brake rotor from the hub with a hammer.
• If the connection cannot be separated, use rust remover.
Installing
Install in the reverse order of removal while noting the following:
– Check the brake rotors for wear and damage before reusing
them. Refer to ⇒ R5.4 otor, Checking”, page 13 .
– Thoroughly clean the brake rotor and hub contact surfaces
and clear them of corrosion.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Place the brake rotor on the wheel hub.

• Do not tilt the brake rotor when mounting it on the wheel
hub.
– Tighten the bolt -arrow- to the tightening specification.

– Install the brake carrier. Refer to ⇒ C3.3 aliper, Removing

and Installing”, page 138 .
– Install the brake caliper. Refer to ⇒ C3.3 aliper, Removing
and Installing”, page 138 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -3.1 Rear Brakes”, page 127

3.7 Brake Shield, Removing and Installing

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Removing
– Remove the brake rotor. Refer to ⇒ R3.6 otor, Removing
and Installing”, page 146 .
Vehicle with torsion beam axle or closed brake shield:
– Remove the wheel bearing unit. Refer to ⇒ Suspension,
Wheels, Steering; Rep. Gr. 42; Wheel Bearing, Trailing Arm;
Wheel Bearing Unit Removing and Installing.
– Remove the brake carrier. Refer to ⇒ C3.5 arrier, Removing
and Installing”, page 145 .

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 147

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Continuation for vehicles with torsion beam axle:

– Remove the bolts -arrows- and remove the brake shield -1-
together with the axle stubs.
Continuation for vehicles with multi-link suspension:

– Remove the bolts -arrows- and remove the brake shield -1-
(example illustration).
Installing
Install in the reverse order of removal while noting the following:
– Clean the contact surfaces on the brake shield and wheel
hub.
– Install the bolts for the brake shield and tighten to the re‐
quired tightening specification.
– If removed, install the brake carrier. Refer to ⇒ C3.5 arrier,
Removing and Installing”, page 145 .
– If removed, install the wheel bearing unit. Refer to ⇒ Sus‐
pension, Wheels, Steering; Rep. Gr. 42; Wheel Bearing,
Trailing Arm; Wheel Bearing Unit, Removing and Installing.
– Install the brake rotor. Refer to ⇒ R3.6 otor, Removing and
Installing”, page 146 .
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
CAUTION 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.

Faulty brakes increase the risk of an accident.

– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -3.1 Rear Brakes”, page 127
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 42;
Wheel Bearing and Trailing Arm; Overview - Wheel Bearing.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
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4 Parking Brake
⇒ -4.1 Parking Brake”, page 149
⇒ P4.2 arking Brake MotorV282/Right Parking Brake Mo‐
torV283, Removing and Installing”, page 150
⇒ B4.3 rake, Manually Loosening”, page 152

4.1 Overview - Parking Brake

Due to a mechanical or electrical malfunction, the parking brake
may need to be released manually in order to move the vehicle.
Refer to ⇒ B4.3 rake, Manually Loosening”, page 152 .

1 - Rear Brake Caliper

2 - Seal
❑ Replace after removing
3 - Bolt
❑ 8 Nm
4 - Parking Brake Motor
♦ Left Parking Brake 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
-V282- with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Right Parking Brake Motor

-V283-
❑ Refer to ⇒ P4.2 arking
Brake MotorV282/Right
Parking Brake Mo‐
torV283, Removing and
Installing”, page 150
5 - ABS Control Module -
J104-
❑ The control for the elec‐
tro-mechanical parking
brake is integrated in
the ABS Control Mod‐
ule -J104-.
❑ Refer to ⇒
A4.2 BS Control Mod‐
uleJ104/ABS Hydraul‐
ic UnitN55, Removing
and Installing”, page 31
6 - Electromechanical Parking
Brake Button -E538-
❑ With Electromechanical
Parking Brake Indicator
Lamp -K213-
❑ Component location,
removing and installing.
Refer to ⇒ Electrical Equipment; Rep. Gr. 96; Controls; Component Location Overview - Controls in
the Center Console.
7 - Instrument Cluster
❑ With Parking Brake Indicator Lamp -K139-
❑ The indicator lamp cannot be replaced separately.
❑ Refer to ⇒ Electrical Equipment; Rep. Gr. 90; Instrument Cluster; Overview - Instrument Cluster.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

4.2 Left Parking Brake Motor -V282-/Right

Parking Brake Motor -V283-, Remov‐
ing and Installing
Special tools and workshop equipment required
♦ Vehicle Diagnostic Tester
♦ Hex Socket -T10621-

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.

♦ Lubricating Grease. Refer to ⇒ Electronic Parts Catalog (ET‐

KA).
Removing

CAUTION
Risk of accident due to the vehicle rolling away.
– Before removing the parking brake motor, secure the vehi‐
cle from rolling.

– Release the parking brake.

– Switch off the ignition.
– Disconnect the connector -1-.

– Remove the bolts -arrows-.

– Remove the parking brake motor from the brake caliper,
while doing so turn the parking brake motor back and forth.
– Remove the seal.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Installing

Install in the reverse order of removal while noting the following:

• Replace the seal after removal.
• The ring groove -arrow- for the gasket and the parking brake
motor contact surface must not be damaged.
– Clean the parking brake motor ring groove and contact sur‐
face.
– Coat the new seal -1- thin with Lithium Grease and install.
– Completely grease the Torx insert on the parking brake mo‐
tor drive axle.
– Slightly turn back the input shaft using the Socket -T10621-
-item A- until the parking brake motor can be positioned
correctly.

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.

• Do not remove the gasket -1- when assembling the parking

brake motor.
– Rotate the parking brake motor until the bolt and threads are
aligned.
• The parking brake motor must be flush with the brake cali‐
per. Under no circumstances may it be pulled against the
brake caliper with bolts.
– Tighten the bolt -arrows- to the tightening specification.

4. Parking Brake 151

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Connect the connector -1-.

– After installation, select the “Electromechanical Parking
Brake Control Module - J540” program. Refer to ⇒
E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -4.1 Parking Brake”, page 149

4.3 Parking Brake, Manually Loosening

Due to a mechanical or electrical malfunction, it may be re‐
quired to mechanically release the parking brake in order to
move the vehicle.
Special tools and workshop equipment required
♦ Hex Socket -T10621-

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.

Procedure

CAUTION
Risk of accident due to the vehicle rolling away.
– Before removing the parking brake motor, secure the vehi‐
cle from rolling.

– Remove the rear wheel. Refer to ⇒ Suspension, Wheels,

Steering; Rep. Gr. 44; Wheels, Tires.

152 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Disconnect the connector -1-.

– Remove the bolts -arrows-.

– Remove the parking brake motor from the brake caliper,
while doing so turn the parking brake motor back and forth.
– Slightly turn back the input shaft using the Socket -T10621-
-item A- until the parking brake motor can be positioned
correctly.

– After eliminating the fault, install the parking brake motor.

Refer to ⇒ P4.2 arking Brake MotorV282/Right Parking
Brake MotorV283, Removing and Installing”, page 150 .
Tightening Specifications
♦ Refer to ⇒ -4.1 Parking Brake”, page 149
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

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. Parking Brake 153

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

5 Brake Pedal
⇒ -5.1 Brake Pedal”, page 154
⇒ P5.2 edal, Disconnecting from Brake Booster”, page 157
⇒ P5.3 edal, Attaching to Brake Booster”, page 158
⇒ P5.4 edal, Removing and Installing”, page 159
⇒ B5.5 racket, Removing and Installing”, page 162

5.1 Overview - Brake Pedal

⇒ -5.1.1 Brake Pedal, LHD”, page 154

5.1.1 Overview - Brake Pedal, LHD

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.

154 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Pedal
❑ The path of the brake
pedal must not be
shortened by extra floor
mats
❑ Refer to ⇒ P5.2 edal,
Disconnecting from
Brake Booster”, page
157
❑ Refer to ⇒ P5.3 edal,
Attaching to Brake
Booster”, page 158
❑ Refer to ⇒ P5.4 edal,
Removing and Instal‐
ling”, page 159 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
2 - Bearing Bushing with respect to the correctness of information in this document. Copyright by AUDI AG.

❑ Cannot be replaced
❑ Note the installation po‐
sition
3 - Mounting Pin
❑ Remove the mounting
bracket to remove.
❑ Do not lubricate or
grease. The mounting
pin must remain dry
4 - Bearing Shell
❑ Installed between the
brake booster mount
and the brake pedal
5 - Mount
❑ For the brake booster
ball head
6 - Bearing Bushing
❑ Cannot be replaced
❑ Note the installation position
7 - Bushing
❑ Oval
8 - Bushing
❑ Round
9 - Bushings
❑ Oval
10 - Bracket
❑ For Headlamp Range Control Module -J431-
11 - Headlamp Range Control Module -J431-
12 - Expanding Clip
13 - Nut
❑ Self-locking
❑ Replace after removing
❑ Tightening specification and sequence. Refer to ⇒ Fig. ““Mounting Bracket - tightening specification
and sequence”“, page 156 .
14 - Clip

5. Brake Pedal 155

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

❑ For mounting pin

❑ Replace after removing
15 - Pedal Assembly/Mounting Bracket
❑ Refer to ⇒ B5.5 racket, Removing and Installing”, page 162
16 - Pedal Rubber

Mounting Bracket - tightening specification and sequence

– Tighten the nuts to 25 Nm in the sequence shown (shown on

LHD).

5.1.2 Overview - Brake Pedal, RHD -- Not for North American Market
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.

156 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Mount
❑ For the brake booster
ball head
2 - Mounting Bracket
3 - Mounting Pin
❑ Remove the mounting
bracket to remove.
❑ Do not lubricate or
grease. The mounting
pin must remain dry
4 - Bushing
❑ Round
5 - Bushing
❑ Oval
6 - Bolt
❑ 20 Nm
7 - Bushing
❑ Round
8 - Metal Nut
9 - Circlip
10 - Clip
❑ For mounting pin
❑ Replace after removing
11 - Nut
❑ Quantity: 3
❑ Self-locking
❑ Replace after removing
❑ Refer to ⇒ Fig. ““Mount‐
ing Bracket - tightening
specification and sequence”“, page 156
12 - Bearing Bushings
❑ Cannot be replaced
❑ Note the installation position
13 - Brake Pedal
❑ The path of the brake pedal must not be shortened by extra floor mats
❑ Refer to ⇒ P5.2 edal, Disconnecting from Brake Booster”, page 157
❑ Refer to ⇒ P5.3 edal, Attaching to Brake Booster”, page 158
❑ Refer to ⇒ P5.4 edal, Removing and Installing”, page 159
14 - Pedal Rubber
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

5.2 Brake Pedal, Disconnecting from

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

Brake Booster
Special tools and workshop equipment required

5. Brake Pedal 157

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Release Tool -T10159B-

Procedure

– Press and hold the brake pedal -1- in the direction of the
brake booster. (Shown on a removed pedal assembly.)
– Insert the Release Tool -T10159B- -item A- and pullunless
in the
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
direction of the driver seat. While doing so, counterhold
with respect toat
the correctness of information in this document. Copyright by AUDI AG.
the brake pedal so that it does not move toward the rear.
While doing so, the mount retaining tabs -3- will be pushed
out of the pushrod ball head -2-.
– Push the Release Tool and the brake Pedal at the same
time toward the driver side, this will pull the brake pedal off
the push rod ball head.
4 - Mounting Bracket

5.3 Brake Pedal, Attaching to Brake Boos‐

ter
Procedure
– Hold the pushrod ball head -1- in front of the mount -2- and
push the brake pedal -3- toward the brake booster -arrow-
until the ball head engages audibly.

158 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

5.4 Brake Pedal, Removing and Installing

⇒ P5.4.1 edal, Removing and Installing, LHD”, page 159

5.4.1 Brake Pedal, Removing and Installing,

LHD
Removing
– Remove the footwell vent on the driver side. Refer to
⇒ Heating, Ventilation and Air Conditioning; Rep. Gr. 87;
Air Routing; Overview - Passenger Compartment Air Routing
and Air Distribution.
– Remove the crash bolster. Refer to ⇒ Body Interior; Rep.
Gr. 70; Instrument Panel Crossmember; Crash Bolster, Re‐
moving
Protected andCopying
by copyright. Installing.
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
– withDisconnect the brake
respect to the correctness pedal from
of information the brake
to
in this document. booster.
Copyright by AUDIRefer
AG.
⇒ P5.2 edal, Disconnecting from Brake Booster”, page 157 .
– Remove the buttons -arrows-.

– Free up the carpet in the area of the universal joint and push
it slightly rearward.

5. Brake Pedal 159

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the bolt -1- and remove the universal joint -2- from
the steering gear -arrow-.

– Remove the clamp -2-.

– Remove the mounting pin -1- at the same time turn the
steering column a maximum 180°.
– Push back the steering column in the previous position.
– Remove the brake pedal -3- downward from the mounting
bracket.
Installing 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 in the reverse order of removal while noting thewith
following:
respect to the correctness of information in this document. Copyright by AUDI AG.

• Both bearing bushings must be located in the brake pedal

bearing so that the brake pedal is securely guided into the
mounting bracket.
– Push in the mounting pin -1-.

– Push on the clamp -2- until it clicks into place on the mount‐
ing pin.

160 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Attach the brake pedal to the brake booster. Refer to ⇒

P5.3 edal, Attaching to Brake Booster”, page 158 .
– Attach the universal joint to the steering gear. Refer to
⇒ Suspension, Wheels, Steering; Rep. Gr. 48; Steering Col‐
umn; Steering Column, Removing and Installing.
– Install the crash bolster. Refer to ⇒ Body Interior; Rep.
Gr. 70; Instrument Panel Crossmember; Crash Bolster, Re‐
moving and Installing.
– Install the driver side footwell vent. Refer to ⇒ Heating, Ven‐
tilation and Air Conditioning; Rep. Gr. 87; Air Duct; Overview
- Air Ducts and Air Distribution in Passenger Compartment.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

5.4.2 Brake Pedal, Removing and Installing,

RHD Vehicle -- Not for North American
Market
Special tools and workshop equipment required
♦ 14 mm Hex Socket Wrench
Removing
– Remove the footwell vent on the driver side. Refer to
⇒ Heating, Ventilation and Air Conditioning; Rep. Gr. 87;
Air Routing; Overview - Passenger Compartment Air Routing
and Air Distribution.
– If installed, remove the TV Tuner -R78- and bracket. Refer to
⇒ Communication; Rep. Gr. 91; Components/Control Mod‐
ules; TV Tuner -R78-, Removing and Installing.
– Disconnect the brake pedal from the brake booster. Refer to
⇒ P5.2 edal, Disconnecting from Brake Booster”, page 157 .
– Remove the clamp -1- at the same time push the control
module -2- slightly to the side.

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

– Remove the mounting pin -3- -arrow-.

– Remove the brake pedal -4- out of the mounting bracket -5-.
Installing
Install in the reverse order of removal while noting the following:
• Replace the clip after removal.
• Do not lubricate or grease the mounting pin.

5. Brake Pedal 161

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• Both bearing bushings must be located in the brake pedal

bearing so that the brake pedal is securely guided into the
mounting bracket.
– Push in the mounting pin -1-.

– Push on the clamp -2- until it clicks into place on the mount‐
ing pin.
– Brake Pedal, Attaching to Brake Booster. Refer to ⇒
P5.3 edal, Attaching to Brake Booster”, page 158 .
– Install the TV Tuner -R78-. Refer to ⇒ Communication; Rep.
Gr. 91; Components/Control Modules; TV Tuner -R78-, Re‐
moving and Installing.
– Install the driver side footwell vent. Refer to ⇒ Heating, Ven‐
tilation and Air Conditioning; Rep. Gr. 87; Air Duct; Overview
- Air Ducts and Air Distribution in Passenger Compartment.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ Body Interior; Rep. Gr. 70; Vehicle Interior Trim
Panels; Overview - Footrest and Carpet.

5.5 Mounting Bracket, Removing and In‐

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
stalling 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.
⇒ B5.5.1 racket, Removing and Installing, LHD Vehicle”, page
162

5.5.1 Mounting Bracket, Removing and In‐

stalling, LHD Vehicle
Removing
– Remove the crash bolster. Refer to ⇒ Body Interior; Rep.
Gr. 70; Instrument Panel Crossmember; Crash Bolster, Re‐
moving and Installing.
– Disconnect the brake pedal from the brake booster. Refer to
⇒ P5.2 edal, Disconnecting from Brake Booster”, page 157 .
– Remove the buttons -arrows-.

162 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Free up the carpet in the area of the universal joint and push
it slightly rearward.
– Remove the bolt -1- and remove the universal joint -2- from
the steering gear -arrow-.

– Release the Headlamp Range Control Module -J431-

-A arrows- and remove it upward from the bracket -1-
-arrow B-

– Disconnect the connector -2- on the control module

– Disconnect the connector -2- on the accelerator pedal mod‐
ule -3- and free up the wire.
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. Brake Pedal 163

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the nuts -1 and 4- and then remove the mounting

bracket.

Installing
Install in the reverse order of removal while noting the following:
– Bring the mounting bracket with the installed brake pedal
into the installation position.
• Make sure that the wire for the accelerator pedal module is
not pinched when inserting the mounting bracket.
• Make sure that the mounting bracket sits in all stud bolts.
– Attach the universal joint to the steering gear. Refer to
⇒ Suspension, Wheels, Steering; Rep. Gr. 48; Steering Col‐
umn; Steering Column, Removing and Installing.
– Attach the brake pedal to the brake booster. Refer to ⇒
P5.3 edal, Attaching
Protected to Copying
by copyright. BrakeforBooster”, page 158
private or commercial . in part or in whole, is not
purposes,
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
– Install the with
crash bolster.
respect Refer oftoinformation
to the correctness ⇒ Bodyin Interior; Rep.
this document. Copyright by AUDI AG.
Gr. 70; Instrument Panel Crossmember; Crash Bolster, Re‐
moving and Installing.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

164 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Tightening Specifications
♦ Refer to ⇒ Fig. ““Mounting Bracket - tightening specification
and sequence”“, page 156

5.5.2 Mounting Bracket, Removing and In‐

stalling, RHD -- Not for North American
Market
Removing
– Disconnect the brake pedal from the brake booster. Refer to
⇒ P5.2 edal, Disconnecting from Brake Booster”, page 157 .
– If installed, remove the TV Tuner -R78- and bracket. Refer to
⇒ Communication; Rep. Gr. 91; Components/Control Mod‐
ules; TV Tuner -R78-, Removing and Installing.
– Remove the windshield wiper motor. Refer to ⇒ Electrical
Equipment; Rep. Gr. 92; Windshield Wiper System; Wind‐
shield Wiper Motor -V-, Removing and Installing.
– Remove the bolt -arrow-.

– Disconnect the connectors -arrows- on the accelerator pedal

module (example 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.

– Free up the wiring harness -2- on the mounting bracket

-arrows- (example illustration).

5. Brake Pedal 165

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the nuts -arrows- and then remove the mounting

bracket.

Installing
Install in the reverse order of removal while noting the following:
– Bring the mounting bracket with the installed brake pedal
into the installation position.
• Make sure that the wire for the accelerator pedal module is
not pinched when inserting the mounting bracket.
• Make sure that the mounting bracket sits in all stud bolts.
– Install the windshield wiper motor. Refer to ⇒ Electrical
Equipment; Rep. Gr. 92; Windshield Wiper System; Wind‐
shield Wiper Motor -V-, Removing and Installing.
– Install the TV Tuner -R78-. Refer to ⇒ Communication; Rep.
Gr. 91; Components/Control Modules; TV Tuner -R78-, Re‐
moving and Installing.
– Brake Pedal, Attaching to Brake Booster. Refer to ⇒
P5.3 edal, Attaching to Brake Booster”, page 158 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Refer to ⇒ Fig. ““Mounting Bracket - tightening specification
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
and sequence”“, page 156 with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Refer to ⇒ Body Interior; Rep. Gr. 70; Vehicle Interior Trim

Panels; Overview - Footrest and Carpet.

166 Rep. Gr.46 - Mechanical Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

47 – Hydraulic Components
1 Safety Precautions
Observe the safety instructions. Refer to ⇒ P2 recautions”, page
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.

1. Safety Precautions 167

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2 Front Brake Caliper

⇒ -2.1 Front Brake Caliper”, page 168
⇒ C2.2 aliper Piston, Removing and Installing”, page 171
⇒ B2.3 ushing and Guide Pin, Replacing”, page 181

2.1 Overview - Front Brake Caliper

⇒ -2.1.1 Front Brake Caliper, Single-Piston Brake 1ZD”, page
168
⇒ -2.1.2Protected
FrontbyBrake Caliper, Single-Piston Brake excluding
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
1ZD”, page with169
respect to the correctness of information in this document. Copyright by AUDI AG.

⇒ -2.1.3 Front Brake Caliper, Dual-Piston Brake”, page 169

⇒ -2.1.4 Front Brake Caliper, Six-Piston Brake”, page 170

2.1.1 Overview - Front Brake Caliper, Single-Piston Brake 1ZD

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

1 - Brake Caliper Housing

2 - Bearing Bushing
❑ Refer to ⇒ B2.3.1 ush‐
ing and Guide Pin, Re‐
placing, Single-Piston
Brake 1ZD”, page 181
3 - Guide Pin
❑ Refer to ⇒ B2.3.1 ush‐
ing and Guide Pin, Re‐
placing, Single-Piston
Brake 1ZD”, page 181
4 - Cap
5 - Seal
❑ Refer to ⇒ C2.2.1 aliper
Piston, Removing and
Installing, Single-Piston
Brake”, page 171
6 - Protective Cap
❑ If damaged, install the
entire seal set
❑ Refer to ⇒ C2.2.1 aliper
Piston, Removing and
Installing, Single-Piston
Brake”, page 171
❑ Mount the cap sealing
lip on the brake caliper
piston.

168 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

2.1.2 Overview - Front Brake Caliper, Single-Piston Brake excluding 1ZD

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

1 - Brake Caliper
2 - Guide Pin
❑ Refer to ⇒ B2.3 ushing
and Guide Pin, Replac‐
ing”, page 181
3 - Dust Protector
❑ For the guide pins
❑ Refer to ⇒ B2.3 ushing
and Guide Pin, Replac‐
ing”, page 181
4 - Seal
❑ Refer to ⇒ C2.2.1 aliper
Piston, Removing and
Installing, Single-Piston
Brake”, page 171
❑ Do not damage when
installing the brake cali‐
per piston
5 - Brake Caliper 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
❑ Refer toto⇒theC2.2.1
with respect aliper
correctness of information in this document. Copyright by AUDI AG.
Piston, Removing and
Installing, Single-Piston
Brake”, page 171
6 - Protective Cap
❑ If damaged, install the
entire seal set
❑ Refer to ⇒ C2.2.1 aliper
Piston, Removing and
Installing, Single-Piston
Brake”, page 171
❑ Pull onto the brake cal‐
iper piston with the out‐
er sealing lip
❑ Do not damage when
installing the brake caliper piston

2.1.3 Overview - Front Brake Caliper, Dual-Piston Brake

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

2. Front Brake Caliper 169

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Caliper
2 - Brake Hose
3 - Bleed Screw
4 - Protective Cap
❑ Refer to ⇒ C2.2.2 aliper
Piston, Removing and
Installing, Dual-Piston
Brake”, page 174
5 - Seal
❑ Refer to ⇒ C2.2.2 aliper
Piston, Removing and
Installing, Dual-Piston
Brake”, page 174
6 - Brake Caliper Piston
❑ Refer to ⇒ C2.2.2 aliper
Piston, Removing and
Installing, Dual-Piston
Brake”, page 174
7 - Protective Cap
❑ If damaged, install the
entire seal set
❑ Refer to ⇒ C2.2.2 aliper
Piston, Removing and
Installing, Dual-Piston
Brake”, page 174
❑ Mount the cap sealing
lip on the brake caliper
piston.

2.1.4 Overview - Front Brake Caliper, Six-Piston Brake

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

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.

170 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Caliper
❑ Shown in place of the
steel brakes
2 - Seal
❑ If damaged, install the
entire seal set
❑ Refer to ⇒ C2.2.3 alip‐
er Piston, Removing
and Installing, Six-Pis‐
ton Brake”, page 178
3 - Brake Caliper Piston
❑ No replacement part
4 - Protective Cap
❑ If damaged, install the
entire seal set
❑ Refer to ⇒ C2.2.3 alip‐
er Piston, Removing
and Installing, Six-Pis‐
ton Brake”, page 178
❑ Mount the cap sealing
lip on the brake caliper
piston.

2.2 Brake Caliper Piston, Removing and

Installing
⇒ C2.2.1 aliper Piston, Removing and Installing, Single-Piston
Brake”, page 171
⇒ C2.2.2 aliper Piston, Removing and Installing, Dual-Piston
Brake”, page 174
⇒ C2.2.3 aliper Piston, Removing and Installing, Six-Piston
Brake”, page 178

2.2.1 Brake Caliper Piston, Removing and

Installing, Single-Piston Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required
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 Brake Caliper 171

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Trim Removal Wedge -3409-

♦ Piston Resetting Tool -T10145-

Removing
• The brake caliper is removed. Refer to ⇒ C2.4.1 aliper, Re‐
placing, Single and Dual-Piston Brakes”, page 106 .
– Tension the brake caliper in a vise with protective covers
over the jaws.
TIP:
When removing the brake caliper piston and the protective cap
make sure that the paint coating on the brake caliper is not
damaged.
– Place a wooden board -A- into the recess so the brake cali‐
per piston is not 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.

172 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Leaking brake fluid increases the risk of injury.
Irritation and injury to the skin and eyes are possible.
– Wear protective eyewear.
– Wear safety gloves.

– Place a cloth tightly around the compressed air gun nozzle

on the brake caliper to catch any spraying brake fluid.
– Position the compressed air gun nozzle on the hole -arrow-
for the brake hose and press the brake caliper piston out of
the brake caliper.
– Remove the protective cap from the brake caliper using the
Trim Removal Wedge -3409- -item A-.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
– Remove the seal -2- from the brake caliper -3- using the
Trim Removal Wedge -3409- -item 1-.

• When removing, make sure that the cylinder surface is not

damaged.
Installing
• Install the entire repair kit.
• Only use mineral spirits to clean the brakes.
• When a brake caliper piston or a piston cylinder are dam‐
aged, the brake caliper must be replaced.
– Insert the seal into the brake caliper.
– Place the protective cap -2- with outer sealing lip on the
brake caliper piston -1-.

2. Front Brake Caliper 173

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Insert the inner sealing lip in the cylinder groove using the
Trim Removal Wedge -3409- -item A- at the same time hold
the brake caliper piston in front of the brake caliper.

– Press the brake caliper piston in the brake caliper using the
Piston Resetting Tool -T10145- -item A- do not tilt it while
doing so.

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.

• Outer sealing lip of protective cap will then engage in the

brake caliper piston groove.

2.2.2 Brake Caliper Piston, Removing and

Installing, Dual-Piston Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required

174 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Trim Removal Wedge -3409-

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or

Brake Charger/Bleeder Unit -VAS 5234-

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.

♦ Piston Resetting Tool -T10145-

♦ Reservoir for brake fluid

Removing
• The brake caliper is removed. Refer to ⇒ C2.4.1 aliper, Re‐
placing, Single and Dual-Piston Brakes”, page 106 .
– Tension the brake caliper in a vise with protective covers
over the jaws.
TIP:
Make sure that the paint coat on the brake caliper is not dam‐
aged when removing the brake caliper pistons and the protec‐
tive caps.

2. Front Brake Caliper 175

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Place a wooden board -3- into the recess so the brake cali‐
per piston -2- is not damaged.

CAUTION
Leaking brake fluid increases the risk of injury.
Irritation and injury to the skin and eyes are possible.
– Wear protective eyewear.
– Wear safety gloves.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Place a cloth tightly around the compressed air gun nozzle
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.
on the brake caliper to catch any spraying brake fluid.
– Position the compressed air gun nozzle on the hole -arrow-
for the brake hose and press the brake caliper piston out of
the brake caliper -1-.
– Remove the seals -2- from the brake caliper -1- using the
Trim Removal Wedge -3409- -item. 3-.

• When removing, make sure that the cylinder surface is not

damaged.
Installing
• Install the entire repair kit.
• Only use mineral spirits to clean the brakes.
• When a brake caliper piston or a piston cylinder are dam‐
aged, the brake caliper must be replaced.
– Insert the seal into the brake caliper.
– Place the protective cap -2- with outer sealing lip on the
brake caliper piston -1-.

176 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Insert the inner sealing lip -2- in the cylinder groove using
the Trim Removal Wedge -3409- -item 4- at the same time
hold the piston -3- in front of the brake caliper -1-.

– Press the brake caliper piston -3- with the Piston Resetting
Tool -T10145- -item 2- in the brake calipers -1-, at the same
time do not tilt.

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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.

• Outer sealing lip of protective cap will then engage in the

brake caliper piston groove.

2. Front Brake Caliper 177

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Pre-bleeding

– Tension the brake calipers -1- using the bleed screw

-arrow A- upward in a vise with protective covers over the
jaws.
– Place the container for catching brake fluid underneath.
– Open the bleed screw and fill with brake fluid, until it leaks
out of the connection -arrow B- without bubbles using the
collector bottle -2-.
– Close the bleeder screw.

2.2.3 Brake Caliper Piston, Removing and

Installing, Six-Piston Brake
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
Special tools and workshop equipment required
♦ Piston Resetting Tool -T10145-

♦ Thrust Piece -T40325- (not illustrated)

♦ Removal Tool -T40338-

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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.

178 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Lubricating Grease. Refer to ⇒ Electronic Parts Catalog (ET‐

KA).
Removing
• Brake caliper removed and separated from the hydraulic
system. Refer to ⇒ C2.4.2 aliper, Replacing, Six-Piston Steel
Brake”, page 110 .
– Tension the brake caliper in a vise with protective covers
over the jaws.
TIP:
Make sure that the paint coat on the brake caliper is not dam‐
aged when removing the brake caliper pistons and the protec‐
tive caps.

CAUTION
Leaking brake fluid increases the risk of injury.
Irritation and injury to the skin and eyes are possible.
– Wear protective
Protected by copyright.eyewear.
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
– Wear withsafety
respect togloves.
the correctness of information in this document. Copyright by AUDI AG.

– Place a cloth over the brake caliper chamber to catch any

spraying brake fluid. Place another cloth tightly around the
compressed air gun nozzle on the brake caliper.

CAUTION
Risk of injury due to sudden release of the brake caliper pis‐
ton when pressing out.
– Never reach with the fingers into the brake caliper open‐
ing.

TIP:

Only one brake caliper piston can be pressed out at a time.

– Hold the opposite brake caliper piston firmly in the brake
caliper using the Piston Resetting Tool -T10145- -item a-.
– To prevent damage to the brake caliper paint coating,
place a piece of rubber between the Piston Resetting Tool
-T10145- and the brake caliper.
– Block the other brake caliper pistons using wooden blocks
-b-, for example. Also place a wooden board -c- in front of
the Piston Resetting Tool -T10145- -a- so that the brake cal‐
iper piston does not become damaged when being pressed
out.
• The bleed screws are closed.

2. Front Brake Caliper 179

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Position the compressed air gun nozzle on the hole for the
brake hose and press the brake caliper piston out of the
brake caliper.
TIP:

If the same protective caps should be re-installed, use the Re‐

moval Tool -T40338- to remove them without damaging them.
– Carefully pry the protective cap -1- and the seal out of the
brake caliper with the Removal Tool -T40338- -2- using gen‐
tle lifting movements, and do not damage the groove for the
protective cap in the brake caliper while doing so.
Installing
• Install the entire repair kit.
• Only use mineral spirits to clean the brakes.
• When a brake caliper piston or a piston cylinder are dam‐
aged, the brake caliper must be replaced.
– Clean the surface of the brake caliper piston only with miner‐
al spirits and let it dry.
– Apply a thin coat of Lithium Grease to the seal.
– Insert the seal into the brake caliper.
– Install protective cap on the piston.

– Thinly coat the brake caliper pistons and the protective cap
with Lithium Grease before installing.
– Without tilting it, push the brake caliper pistons using con‐
stant pressure.

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.

180 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Press the protective cap into the groove on the brake cali‐
per.
• The protective cap must fit tightly in the groove. If necessa‐
ry, push down on it slightly with the Piston Resetting Tool
-T10145-.
– Repeat the work procedure on the next brake caliper piston.

2.3 Bearing Bushing and Guide Pin, Re‐

placing
⇒ B2.3.1 ushing and Guide Pin, Replacing, Single-Piston Brake
1ZD”, page 181
⇒ P2.3.2 rotector and Guide Pin, Replacing, Single-Piston
Brake excluding 1ZD”, page 182

2.3.1 Bearing Bushing and Guide Pin, Re‐

placing, Single-Piston Brake 1ZD
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.
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
• Install the repair kit if the bearing bushings or guide pins are
damaged.
Removing
– Remove the brake pads. Refer to ⇒ P2.2.1 ads, Removing
and Installing, Single-Piston Brake 1ZD”, page 75 .
– Pull the guide pin -1- outward from the bearing bushing (ex‐
ample illustration).

– Pull the bearing bushing -2- out of the brake caliper.

– Insert the bearing bushing into the brake caliper.
• The bearing bushing must be seated in the center of the
brake caliper.

2. Front Brake Caliper 181

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Slightly coat the guide pin with grease.

– Push the guide pin into the bearing bushing.
– Check the movement of both guide pins.
• Both guide pins must be able to slide.
– Install the brake pads. Refer to ⇒ P2.2.1 ads, Removing and
Installing, Single-Piston Brake 1ZD”, page 75 .

2.3.2 Dust Protector and Guide Pin, Replac‐

ing, Single-Piston Brake excluding 1ZD
Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .
• Install the repair kit if the dust protectors or guide pins are
damaged.
Removing
• The brake caliper is removed. Refer to ⇒ C3.3 aliper, Re‐
moving and Installing”, page 138 .
– Remove the dust protectors -2- from the groove on the brake
carrier -1-.

– Remove the guide pins -3- from Protected

the brake carrier.
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
– Remove the dust protectors from the guide pins.
with respect to the correctness of information in this document. Copyright by AUDI AG.

Installing
– Lubricate the guide pin before inserting.
– Slide the dust protector over the groove on the guide pin.
– Slide the guide pins -3- with the dust protector -2- through
the brake carrier -1-.
– Press the dust protector over the groove on the brake carri‐
er.

182 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

3 Rear Brake Caliper

⇒ -3.1 Rear Brake Caliper”, page 183
⇒ C3.2 ap, Removing and Installing”, page 183
⇒ B3.3 ushing and Guide Pin, Replacing”, page 186

3.1 Overview - Rear Brake Caliper

Allocation of the PR number. Refer to ⇒ D4.1 ata, Brakes”,
page 9 .

1 - Brake Caliper
❑ The brake caliper pis‐
ton cannot be removed
2 - Guide Pin
❑ Refer to ⇒ B3.3 ushing
and Guide Pin, Replac‐
ing”, page 186
3 - Bearing Bushing
❑ Refer to ⇒ B3.3 ushing
and Guide Pin, Replac‐
ing”, page 186
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
4 -permitted
Caps 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 - Bearing Bushing
❑ Refer to ⇒ B3.3 ushing
and Guide Pin, Replac‐
ing”, page 186
6 - Guide Pin
❑ Refer to ⇒ B3.3 ushing
and Guide Pin, Replac‐
ing”, page 186
7 - Protective Cap
❑ Refer to ⇒ C3.2 ap, Re‐
moving and Installing”,
page 183

3.2 Dust Cap, Removing and Installing

Special tools and workshop equipment required

3. Rear Brake Caliper 183

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Trim Removal Wedge -3409-

♦ Piston Resetting Tool -T10145-

♦ Press Piece -T10502-

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.

♦ Hex Socket -T10621-

♦ Lubricating Grease. Refer to ⇒ Electronic Parts Catalog (ET‐

KA).
Removing
• Brake caliper piston is driven back.

184 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• The parking brake motor is removed. Refer to ⇒ P4.2 arking

Brake MotorV282/Right Parking Brake MotorV283, Remov‐
ing and Installing”, page 150 .
• Install the entire repair kit when servicing.

NOTICE
There is a risk of destroying the ball thread by removing from
the brake caliper piston and thrust nut.
– Never completely remove the brake caliper piston and
thrust nut.

– Remove the brake caliper piston maximum 20 mm

-dimension a- counter-clockwise -arrow- using the Hex
Socket - T10621-.
– Remove the protective cap from the brake caliper using the
Trim Removal Wedge -3409-.

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.

Installing
• To clean only use mineral spirits.
– Clean the surfaces on the brake caliper piston and brake
caliper using mineral spirits and then dry.
– Thinly coat the brake caliper pistons and the protective cap
with Lithium Grease before installing.
– Place the protective cap in the groove -arrow- on the brake
caliper piston.

3. Rear Brake Caliper 185

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Install the brake caliper piston clockwise -arrow-.

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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.

– Push the protective cap onto the brake caliper using the
Press Piece -T10502- -item 2- and Piston Resetting Tool
-T10145- -item 1- so that the protective cap is touching the
brake caliper all the way around.

3.3 Bearing Bushing and Guide Pin, Re‐

placing
Removing
– Remove the brake pads. Refer to ⇒ P3.2 ads, Removing
and Installing”, page 130 .
– Pull the guide pin -2- outward from the bearing bushing.

186 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Pull the bearing bushing -1- out of the brake caliper.

Installing
– Insert the new bearing bushing into the brake caliper.
• The bearing bushing must be seated in the center of the
brake caliper.
– Push the guide pin into the bearing bushing.
– Check both guide pins for ease of movement.
• Both guide pins must be able to slide.
– Install
Protected the brake
by copyright. Copying pads.
for privateRefer to ⇒ purposes,
or commercial P3.2 ads,
in partRemoving and
or in whole, is not
Installing”,
permitted page
unless authorised 130AG.
by AUDI . 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 Brake Caliper 187

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

4 Brake Booster/Brake Master Cylin‐

der
⇒ -4.1 Brake Booster/Brake Master Cylinder”, page 188
⇒ B4.2 ooster, Removing and Installing”, page 191
⇒ M4.3 aster Cylinder, Removing and Installing”, page 196
⇒ F4.4 luid Reservoir, Removing and Installing”, page 201
⇒ B4.5 rake Fluid Level Warning SwitchF34, Removing and
Installing”, page 205

4.1 Overview - Brake Booster/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.

188 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

1 - Brake Line
❑ Brake master cylin‐
der/primary piston cir‐
cuit to hydraulic unit
❑ Tightening Specifica‐
tions
♦ With standard tool: 14 Nm
♦ With special tool Refer to
⇒ Fig. ““Brake lines tight‐
ening using special tools”“,
page 190 12 Nm
2 - Brake Master Cylinder
❑ There are different ver‐
sions. Refer to the
⇒ Electronic Parts Cat‐
alog (ETKA) for the al‐
location. 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
❑ Cannot be serviced.
with respectIfto the correctness of information in this document. Copyright by AUDI AG.
malfunctioning, replace
as complete unit.
❑ Refer to ⇒ M4.3 as‐
ter Cylinder, Removing
and Installing”, page
196
3 - Brake Line
❑ Brake master cylin‐
der/secondary piston
circuit to hydraulic unit
❑ Tightening Specifica‐
tions
♦ With standard tool: 14 Nm
♦ With special tool Refer to
⇒ Fig. ““Brake lines tight‐
ening using special tools”“,
page 190 12 Nm
4 - Plugs
❑ Replace the brake master cylinder if damaged
❑ To install, coat with brake fluid
5 - Brake Fluid Reservoir
❑ There are different versions. Refer to the ⇒ Electronic Parts Catalog (ETKA) for the allocation.
❑ Refer to ⇒ F4.4 luid Reservoir, Removing and Installing”, page 201
6 - Locking Pin
❑ Slide through the brake fluid reservoir and the master brake cylinder
❑ The locking pin must be pushed into the brake fluid reservoir tab.
7 - Brake Fluid Level Warning Switch -F34-
❑ Refer to ⇒ B4.5 rake Fluid Level Warning SwitchF34, Removing and Installing”, page 205
8 - Cap
❑ With gasket
❑ The seal is not available separately
9 - Nut
❑ Self-locking
❑ Replace after removing

4. Brake Booster/Brake Master Cylinder 189

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

❑ Refer to ⇒ Fig. ““Brake booster - tightening specification and sequence”“, page 190
10 - Seal
❑ Replace after removing
11 - Brake Booster -NX6-
❑ with
♦ Brake Pedal Position Sensor -G100-
♦ Brake Pedal Position Sensor 2 -G836-
♦ Power Supply Sensor Protected
1 -G730- by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Power Supply Sensor 2 -G731-
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 Booster Voltage Sensor -G822-

♦ Brake Booster Temperature Sensor 1 -G838-
♦ Brake Booster Temperature Sensor 2 -G839-
♦ Brake Booster Motor Position Sensor -G840-
♦ Brake Booster Control Module -J539-
♦ Electro-Mechanical Brake Booster Motor -V548-
The components in the brake booster cannot be replaced individually.

Check the function of the brake lamp after installation of the brake booster.
❑ Refer to ⇒ B4.2 ooster, Removing and Installing”, page 191
12 - O-Ring
❑ Replace the brake master cylinder if damaged
13 - Nut
❑ 23 Nm

Brake booster - tightening specification and sequence

– Tighten the nuts to 25 Nm in the sequence -3 and 4- (shown

on LHD).
Brake lines tightening using special tools

190 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Special tools and workshop equipment required

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
♦ Open Ring Spanner permitted
Insert unless
- AF authorised
11mm -V.A.G 1410/6-
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.
♦ Torque Wrench - Universal Joint -V.A.G 1410/7-
♦ Mini Torque Wrench -VAS 6854-
Heat shield - tightening specification

– Tighten the bolt -arrow- to 8 Nm.

4.2 Brake Booster, Removing and Instal‐

ling
⇒ B4.2.1 ooster, Removing and Installing, LHD Vehicles”, page
191

4.2.1 Brake Booster, Removing and Instal‐

ling, LHD Vehicles
Special tools and workshop equipment required
♦ Hot air gun, for example, Wiring Harness Repair Set - Hot
Air Blower -VAS 1978/14A-

4. Brake Booster/Brake Master Cylinder 191

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Removing
– If replacing the brake booster, select the “Control Module,
Replacing” program. Refer to ⇒ E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.
– Remove the main brake cylinder. Refer to ⇒ M4.3 aster
Cylinder, Removing and Installing”, page 196 .
Vehicles with high-voltage system:
– Remove the bracket for the Electric Drive Power and Control
Electronics -JX1-. Refer to ⇒ Rep. Gr. 93; Electric Drive
Power and Control Electronics; Electric Protected
Drive Power and
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Control Electronics -JX1-, Removing andpermitted
Installing.
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.
Continuation for All Vehicles:

– Disconnect the connector -arrow-.

– Disconnect the brake pedal from the brake booster. Refer to
⇒ P5.2 edal, Disconnecting from Brake Booster”, page 157 .
– Remove the nuts -3 and 4- for the brake booster.

– Pull the brake booster off the bonding on the bulkhead and
remove it.
Installing
Install in the reverse order of removal while noting the following:
• Replace the seal between the brake booster and bulkhead.
• The new seal is not bonded.
– Remove any bonded joint -arrows- residue from the brake
booster -2- and the bulkhead -1-.

192 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Using a hot air gun, warm the adhesive residue at a low

setting and remove it.
– Clean the surfaces thoroughly.
– Attach the brake pedal to the brake booster. Refer to ⇒
P5.3 edal, Attaching to Brake Booster”, page 158 .
– Install the brake master cylinder. Refer to ⇒ M4.3 aster Cyl‐
inder, Removing and Installing”, page 196 .
– After removing and installing the same brake booster, se‐
lect the “Brake booster basic setting” program. Refer to ⇒
E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.
– Complete the “Control Module, Replacing” program after re‐
placing the brake booster. Use the ⇒ Vehicle diagnostic test‐
er.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle
Protected for the
by copyright. firstfortime.
Copying private or commercial purposes, in part or in whole, is not
– Check the brake lamp function.
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.

Tightening Specifications
♦ Refer to ⇒ -4.1 Brake Booster/Brake Master Cylinder”, page
188

4.2.2 Brake Booster, Removing and Instal‐

ling, RHD Vehicle -- Not for North
American Market
Special tools and workshop equipment required

4. Brake Booster/Brake Master Cylinder 193

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Hot air gun, for example, Wiring Harness Repair Set - Hot
Air Blower -VAS 1978/14A-

Removing
– If replacing the brake booster, select the “Control Module,
Replacing” program. Refer to ⇒ E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.
Vehicle with 1.0L TFSI:
– Remove the refrigerant lines with the inner heat exchanger.
Refer to ⇒ Heating, Ventilation and Air Conditioning; Rep.
Gr. 87; Refrigerant Circuit; Refrigerant Lines with Inner Heat
Exchanger, Removing and Installing.
Vehicle with 1.5L/2.0L TFSI and 2.0L TDI
– Remove the catalytic converter. Refer to ⇒ Engine; Rep.
Gr. 26; Emissions Control; Catalytic Converter, Removing
and Installing.
Continuation for All Vehicles:
– Remove the mounting bracket. Refer to ⇒ B5.5.2 racket,
Removing and Installing, RHD -- Not for North American
Market”, page 165 .
– Remove the main brake cylinder. Refer to ⇒ M4.3.2 aster
Cylinder, Removing and Installing, RHD Vehicles -- Not for
North American Market ”, page 198 .
– Move the noise insulation -1- to the side.

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

– Remove the brake booster out of the bonding, at the same

time warm the bulkhead -2- using the hot air gun on low
heat.
– Disconnect the connectors -1 and 2- and remove the brake
booster -3-.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Installing
Install in the reverse order of removal while noting the following:
• Replace the seal between the brake booster and bulkhead.
• The new seal is not bonded.
– Remove any bonded joint residue from the brake booster
and the bulkhead.
– Clean the surfaces thoroughly.
– Install the brake master cylinder. Refer to ⇒ M4.3.2 aster
Cylinder, Removing and Installing, RHD Vehicles -- Not for
North American Market ”, page 198 .
– Bleed the brake system. Refer to ⇒ S5.2 ystem, Bleeding”,
page 208 .
– Install mounting bracket. Refer to ⇒ B5.5.2 racket, Removing
and Installing, RHD -- Not for North American Market”, page
165 .
– Install the catalytic converter. Refer to ⇒ Engine Mechanical;
Rep. Gr. 26; Emissions Control System; Catalytic Converter,
Removing and Installing.
– Install the refrigerant lines with the inner heat exchanger.
Refer to ⇒ Heating, Ventilation and Air Conditioning; Rep.
Gr. 87; Refrigerant Circuit; Refrigerant Line with Inner Heat
Exchanger, Removing and Installing.
– After removing and installing the same brake booster, se‐
lect the “Brake booster basic setting” program. Refer to ⇒
E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.
– Complete the “Control Module, Replacing” program after re‐
placing the brake booster. Use the ⇒ Vehicle diagnostic test‐
er.
– After installing the brake booster for bleeding the hydraulic
system select the program “0023 - Basic Setting, Brake
Bleeding”. Refer to ⇒ E6.1Protected
ntries”,
by page 21
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
Tightening Specifications with respect to the correctness of information in this document. Copyright by AUDI AG.

♦ Refer to ⇒ -4.1 Brake Booster/Brake Master Cylinder”, page

188

4. Brake Booster/Brake Master Cylinder 195

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

4.3 Brake Master Cylinder, Removing and

Installing
⇒ M4.3.1 aster Cylinder, Removing and Installing, LHD Vehi‐
cles”, page 196

4.3.1 Brake Master Cylinder, Removing and

Installing, LHD Vehicles
Special tools and workshop equipment required
♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

♦ Plugs from the Assembly Part Set -5Q0 698 311-: M10
-item 1- and M12 -item 2-

Removing
Vehicles without high-voltage system excluding 2.0L TFSI North
American/2.5L TFSI:
– Remove the battery tray. Refer to ⇒ Electrical Equipment;
Rep. Gr. 27; Battery; Battery Tray, Removing and Installing.
Vehicles with 2.0L TFSI North American:
– Remove the air filter housing. Refer to ⇒ Engine Mechanical;
Rep. Gr. 24; Air Filter; Air Filter Housing, Removing and
Installing.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not

Vehicles with
with high-voltage 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.

– Remove the electric drive power and control electronics.

Refer to ⇒ Rep. Gr. 93; Electric Drive Power and Control
Electronics; Electric Drive Power and Control Electronics,
Removing and Installing.

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Brake System - Edition 01.2023

– Unclip the Drive Motor High-Voltage Wiring Harness -PX2-

-1- from the bracket -3- -arrows- and put to the side.

– Remove the bolt -3- and the nut -2-.

– Remove the bracket -4-.
Continuation for All Vehicles:
– Remove the brake fluid reservoir. Refer to ⇒ F4.4 luid Res‐
ervoir, Removing and Installing”, page 201 .
– To prevent brake fluid from escaping, place enough lint-free
cloths in the area under the brake master cylinder.

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

– Remove the brake lines -1 and 2- from the brake master

cylinder.
– Immediately close open connection points with a clean plug.
– Remove the nuts -arrows-.
– Disconnect and remove the brake master cylinder from the
brake booster.
Installing
Install in the reverse order of removal while noting the following:
• Do not let any brake fluid run into the brake booster.
– When inserting the brake master cylinder, make sure the
pushrod is seated correctly in the brake booster.
– Install the brake fluid reservoir. Refer to ⇒ F4.4 luid Reser‐
voir, Removing and Installing”, page 201 .
– Install the electric drive power and control electronics. Refer
to ⇒ Rep. Gr. 93; Electric Drive Power and Control Electron‐
ics; Electric Drive Power and Control Electronics, Removing
and Installing.

4. Brake Booster/Brake Master Cylinder 197

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Install the air filter housing. Refer to ⇒ Engine Mechanical;

Rep. Gr. 24; Air Filter; Air Filter Housing, Removing and
Installing.
– Install the battery tray. Refer to ⇒ Electrical Equipment; Rep.
Gr. 27; Battery; Battery Tray, Removing and Installing.
– Bleed the brake system. Refer to ⇒ S5.2 ystem, Bleeding”,
page 208 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -4.1 Brake Booster/Brake Master Cylinder”, page
188

4.3.2 Brake Master Cylinder, Removing and

Installing, RHD Vehicles -- Not for
North American Market
Special tools and workshop equipment required
♦ Bleeding Equipment -VAS 6860- or Brake Charger/Bleeder
Unit -VAS 5234-

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

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.

198 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Plugs from the Assembly Part Set -5Q0 698 311-: M10
-item 1- and M12 -item 2-

Removing
Vehicle with 1.5L/2.0L TFSI:
– Remove the refrigerant lines with the inner heat exchanger.
Refer to ⇒ Heating, Ventilation and Air Conditioning; Rep.
Gr. 87; Refrigerant Circuit; Refrigerant Lines with Inner Heat
Exchanger, Removing and Installing.
Continuation for All Vehicles:

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
CAUTION
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.
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

– Extract as much brake fluid -2- as possible with the suction

hose Brake Filling and Bleeding Equipment -VAS 6860- or
Brake Charger/Bleeder Unit -VAS 5234- (example illustra‐
tion).
– To protect against escaping brake fluid, place enough lint-
free cloths in the area below the brake master cylinder.
– Remove bolt -arrow- and then remove the heat shield.

4. Brake Booster/Brake Master Cylinder 199

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Disconnect the connector -2- for the Brake Fluid Level Warn‐
ing Switch -F34-.

– Remove the brake lines -arrows- from the brake master cyl‐
inder -6-.
– Immediately close open connection points with a clean plug.
– Free up the electrical wire.
– Remove the nuts -1 and 5-
• Do not let anything fall in the brake booster when removing
the brake master cylinder.
– Disconnect and remove the heat shield -3- and brake master
cylinder from the brake booster.
Brake Fluid Reservoir, Removing
– Remove the locking pin -4- and the brake fluid reservoir -3-.
Installing
Install in the reverse order of removal while noting the following:
– Coat the plugs on the brake fluid reservoir with brake fluid.
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
– Insert the brake permitted
fluid reservoir into the
unless authorised plugs
by AUDI in the
AG. AUDI brake
AG does not guarantee or accept any liability
master cylinder. with respect to the correctness of information in this document. Copyright by AUDI AG.
– Slide the locking pin through the brake fluid reservoir and the
master brake cylinder.
• The locking pin must be pushed into the brake fluid reservoir
tab.
• Do not let any brake fluid run into the brake booster.
– When inserting the brake master cylinder, make sure the
pushrod is seated correctly in the brake booster.
– Install the refrigerant lines with the inner heat exchanger.
Refer to ⇒ Heating, Ventilation and Air Conditioning; Rep.

200 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

Gr. 87; Refrigerant Circuit; Refrigerant Line with Inner Heat

Exchanger, Removing and Installing.
– Remove all cloths from the vehicle that were previously
placed down.
– Bleed the brake system. Refer to ⇒ S5.2 ystem, Bleeding”,
page 208 .

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -4.1 Brake Booster/Brake Master Cylinder”, page
188

4.4 Brake Fluid Reservoir, Removing and

Installing
⇒ F4.4.1 luid Reservoir, Removing and Installing, LHD Vehicle”,
page 201

4.4.1 Brake Fluid Reservoir, Removing and

Installing, LHD Vehicle
Special tools and workshop equipment required
♦ Bleeding Equipment -VAS 6860- or Brake Charger/Bleeder
Unit -VAS 5234-

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 Booster/Brake Master Cylinder 201

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Plugs from the Repair Kit -1H0 698 311 A-: M10 -item 1- and
M12 -item 2-

♦ Plugs from the Assembly Part Set -5Q0 698 311-: M10
-item 1- and M12 -item 2-

♦ Safety Gloves
Removing
All vehicles excluding 2.5L TFSI:
– Remove the battery. Refer to ⇒ Electrical Equipment; Rep.
Gr. 27; Battery; Battery, Removing and Installing.
Vehicle with 2.5L FSI:
– Remove the air filter housing. Refer to ⇒ Engine Mechanical;
Rep. Gr. 24; Air Filter; Air Filter Housing, Removing and
Installing.
Continuation for All Vehicles:

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

NOTICE
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.
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Rinse off any leaking brake fluid immediately using plenty
of water.

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 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Risk of accident due to the brakes malfunctioning.
– Brake fluid must never come into contact with fluids con‐
taining mineral oils (oil, gasoline, cleaning solutions).
– Wear safety gloves that are free of oil and grease.

– Open the brake fluid reservoir (example illustration).

CAUTION
Risk of accident due to the brakes malfunctioning.
– Brake fluid must never come into contact with fluids con‐
taining mineral oils (oil, gasoline, cleaning solutions).
– Wear safety gloves that are free of oil and grease.

– Extract as much brake fluid from the brake fluid reservoir

as possible using the Brake Filling and Protected
Bleeding Equipment
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
-VAS 6860- or Brake Charger/Bleeder Unit with-VAS
respect 5234- with of information in this document. Copyright by AUDI AG.
to the correctness
a suction hose.
– To protect against escaping brake fluid, place enough lint-
free cloths in the area below the brake master cylinder.
Vehicle with manual transmission:

– Remove the clutch master cylinder return hose -4- on the

brake fluid reservoir -1-.

4. Brake Booster/Brake Master Cylinder 203

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Immediately close the hose with a clean plug and tie up‐
ward.
Continuation for All Vehicles:

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.

– Disconnect the connector -1- from the Brake Booster Control

Module -J539-.
– Disconnect the connector -2- for the Brake Fluid Level Warn‐
ing Switch -F34- (different installation positions).
– Drive out the locking pin -4- and remove the brake fluid
reservoir -3- from the plugs.
Installing
Install in the reverse order of removal while noting the following:
– Coat the plugs on the brake fluid reservoir with brake fluid.
– Insert the brake fluid reservoir into the plugs in the brake
master cylinder.
– Slide the locking pin through the brake fluid reservoir and the
master brake cylinder.
• The locking pin must be pushed into the brake fluid reservoir
tab.
– Fill the brake fluid reservoir up to the “MIN” mark (example
image).

– Remove all cloths from the vehicle that were previously

placed down.
– Bleed the brake system. Refer to ⇒ S5.2 ystem, Bleeding”,
page 208 .
– Bleed the clutch hydraulic. Refer to ⇒ Transmission; Rep.
Gr. 30; Clutch Mechanism; Clutch Mechanism, Bleeding.

204 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Install the air filter housing. Refer to ⇒ Engine Mechanical;

Rep. Gr. 24; Air Filter; Air Filter Housing, Removing and
Installing.
– Install the battery. Refer to ⇒ Electrical Equipment; Rep.
Gr. 27; Battery; Battery, Removing and Installing.
– Check brake fluid level, and fill if necessary.

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

4.4.2 Brake Fluid Reservoir, Removing and

Installing, RHD -- Not for North Ameri‐
can Market
The brake fluid reservoir is removed together with the brake flu‐
id reservoir and then removed from the brake master cylinder.

4.5 Brake Fluid Level Warning Switch -

F34-, Removing and Installing
Removing
Vehicle with 2.5L FSI:

– Release the retainer -arrow A- and open the cap at the Fuse
Panel 4 -ST4- -item 1- -arrow B-.copyright. Copying for private or commercial purposes, in part or in whole, is not
Protected by
permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
Continuation for All Vehicles:with respect to the correctness of information in this document. Copyright by AUDI AG.

– Disconnect the connector -2-.

4. Brake Booster/Brake Master Cylinder 205

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Release the catch -arrow- and remove the Brake Fluid Level
Warning Switch -F34- -item 1- from the brake fluid reservoir
(example illustration).
Installing
Install in reverse order of 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.

206 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

5 Hydraulic System
⇒ F5.1 luid General Information”, page 207
⇒ S5.2 ystem, Bleeding”, page 208
⇒ T5.3 est”, page 214

5.1 Brake Fluid General Information

Brake fluid is hygroscopic, meaning that it has the capability to
absorb water and moisture from the air.

CAUTION
Risk of an accident due to the water content in the brake
fluid being too high. Brake fluid is hygroscopic, meaning that it
absorbs moisture from the surrounding air.
Brake failure due to the formation of steam bubbles.
– Store brake fluid in air-tight containers.
– Immediately seal any open brake hoses and brake lines.

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

If water has been absorbed, the boiling point will drop, for ex‐
ample, during high braking temperatures the brake fluid may
develop steam bubbles and cause the brakes to fail.
Over time, brake fluid will darken in color. Dark-colored brake
fluid does not indicate anything about its quality. The color
forms due to chemical reactions.

CAUTION
Risk of accident due to the brakes malfunctioning.
– Brake fluid must never come into contact with fluids con‐
taining mineral oils (oil, gasoline, cleaning solutions).
– Wear safety gloves that are free of oil and grease.

5. Hydraulic System 207

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

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.

Even the smallest amount of mineral oil on a seal or rubber

grommet can cause the parts to change and thereby affect the
function of the brakes. The results of an unclean brake system
first show themselves months later, causing increased repair
costs, especially on vehicles with ABS.
A - Rubber Grommet - Original Size
B - Rubber Grommet - Swollen Through Contact with Mineral
Oil

CAUTION
Health risk due to poisonous fluid.
– Never extract brake fluid by mouth.

As a result of the previously mentioned points:

♦ Always keep brake fluid containers securely closed. This is
to make sure that no oil, dirt, cleaning materials or humidity
can enter the container.
♦ Store brake fluid containers away from oil (even hydraulic
oil) and cleaning fluids to prevent an accidental mixing of
both fluids or even filling the brake system with the wrong
fluid.

CAUTION
Leaking brake fluid increases the risk of injury.
Risk of skin irritation and injury.
– Wear safety gloves.

• Close the open brake hoses and brake lines with a plug.
• Always store brake fluid in air-tight containers.

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Rinse off any leaking brake fluid immediately using plenty
of water.

• Only use new brake fluid.

• Follow all waste disposal regulations.

5.2 Hydraulic System, Bleeding

Special tools and workshop equipment required

208 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Bleeding Equipment -VAS 6860- or Brake Charger/Bleeder

Unit -VAS 5234-

♦ Brake Charger/Bleeder Unit - Adapter -VAS 5234/1A-

♦ Collection bottle from the Bleeding Equipment -VAS 6860- or
Brake Charger/Bleeder Unit -VAS 5234-

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.

♦ Wrench - Brake Bleeder Set -VAS 5519-

5. Hydraulic System 209

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

♦ Brake Bleeding Tool Set -VAS 6564-

Bleed brakes
The brake system is divided diagonally:
♦ Left front wheel and right rear wheel.
♦ Right front wheel and left rear wheel.
• Depending on the wheel combination, remove the wheels.
Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.
Component Conventional Bleeding with the
bleeding ⇒ Vehicle diagnos‐
tic tester
Brake line from 1 2
brake booster to
hydraulic unit
Hydraulic Unit 1 2
Suction Line 1 2
Brake line from hy‐ 1 –
draulic unit to brake
caliper
Brake Caliper 1 –
1. Conventional bleeding

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.

– Attach the Brake Bleeder Adapter -VAS 5234/1A- to the

brake fluid reservoir (example illustration).
– Connect the filling hose from the Brake Filling and Bleeding
Equipment -VAS 6860- or Brake Charger/Bleeder Unit -VAS
5234-.
– Set a work pressure of 2.0 bar (29.01 psi) at the Bleeding
Equipment -VAS 6860- or Brake Charger/Bleeder Unit -VAS
5234- and turn it on. Refer to ⇒ Owner's Manual.

210 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Remove the protective cap -3- from the bleed screw -1- on
the respective brake caliper (example illustration).

• Use a suitable bleeder hose -2-. It must be seated tightly on

the bleed screw so that no air can enter the brake system.
The six-piston brake calipers each have two bleed screws.

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.

– Position the socket -3- at the bleed screw using the ratchet
-2-.
– Attach the bleeder hose -1- through the socket onto the
bleed screw.
– Position the socket -3- at the inner bleed screw using the
ratchet -2-.

5. Hydraulic System 211

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Attach the bleeder hose -1- through the socket onto the
bleed screw.
• Bleed the brake caliper at each bleed screw.
Bleeding sequence
1- Outer Left Front Six-Piston Brake Caliper
2- Left front inner brake caliper
3- Outer Right Front Six-Piston Brake Caliper
4- Right front inner brake caliper
5- Left Rear Brake Caliper
6- Right Rear Brake Caliper
– Open the bleed screw and leave open until the leaking brake
fluid is clear and without bubbles.
– Press brake pedal five times to assist the bleeding proce‐
dure.
– Tighten the bleed screw, remove the bleeder hose and place
the protective cap on the bleed screw.
– Repeat the bleeding procedure in the specified sequence for
the remaining brake calipers.
– Fill the brake fluid reservoir under consideration of brake
pad wear up to the “MAX” mark and tighten the fuel cap
(example 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.

– Carefully remove leaked brake fluid.

– Start the engine and check the brake pedal travel and pres‐
sure.
• If the brake pedal travel and brake pedal pressure are not
OK, perform the bleeding procedure using the Vehicle Diag‐
nostic Tester.
2. Bleeding using the Vehicle Diagnostic Tester
– Connect the battery charger. Refer to ⇒ Electrical Equip‐
ment; Rep. Gr. 27; Battery; Battery, Charging.
– Attach the Brake Bleeder Adapter -VAS 5234/1A- to the
brake fluid reservoir (example illustration).

212 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

– Connect the filling hose from the Brake Filling and Bleeding
Equipment -VAS 6860- or Brake Charger/Bleeder Unit -VAS
5234-.
– Set a work pressure of 2.0 bar (29.01 psi) at the Bleeding
Equipment -VAS 6860- or Brake Charger/Bleeder Unit -VAS
5234- and turn it on. Refer to ⇒ Owner's Manual.
– Select the “0003 - Basic Setting, Brake Bleeding” program.
Refer to ⇒ E6.1 ntries”, page 21 .
– Follow the instructions in the Vehicle Diagnostic Tester dis‐
play.
– Check the brake pedal travel and brake pedal pressure after
bleeding.
• If the brake pedal travel and brake pedal pressure are not
OK, repeat the bleeding procedure using the ⇒ Vehicle diag‐
nostic tester.
– Remove the Adapter -VAS 5234/1- from the brake fluid res‐
ervoir.
– Fill the brake fluid reservoir under consideration of brake
pad wear up to the “MAX” mark and tighten the fuel cap
(example illustration).

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

NOTICE
There is a risk of contamination and paint damage from leak‐
ing brake fluid.
– Rinse off any leaking brake fluid immediately using plenty
of water.

• A road test must be performed after bleeding. During this, at

least one ABS control must be performed!

5. Hydraulic System 213

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

CAUTION
Faulty brakes increase the risk of an accident.
– Make sure the brakes are working correctly before driving
the vehicle for the first time.

Tightening Specifications
♦ Refer to ⇒ -2.1 Front Brakes”, page 61
♦ Refer to ⇒ -3.1 Rear Brakes”, page 127
♦ Refer to ⇒ Suspension, Wheels, Steering; Rep. Gr. 44;
Wheels, Tires.

5.3 Leak Test

Special tools and workshop equipment required
♦ Brake Pressure Gauge -V.A.G 1310A-

♦ Brake Pedal Actuator -V.A.G 1869/2-.

High Pressure Test:

• Brake system (brake master cylinder, brake hoses, brake
lines and brake calipers) tested for function and leaks.
– Remove the bleed screw at one of the front brake calipers.
Connect the Brake Pressure GaugeCopying
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commercial
bleed. 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.
– Insert the Brake Pedal Actuator -V.A.G 1869/2- -item A- be‐
tween the brake pedal and driver seat. Apply pressure to the
brake pedal until the pressure gauge indicates a pressure of
50 bar (725.19 psi).

214 Rep. Gr.47 - Hydraulic Components

 Audi A3 2021 ➤, Audi A3 China 2021 ➤
Brake System - Edition 01.2023

• The pressure must not drop more than 4 bar (58.02 psi)
during the test period of 45 seconds.
• Replace the brake master cylinder if the pressure decrease
is too high.
Low pressure testing:
– Set the brake pedal actuator back far enough that the pres‐
sure gauge indicates 6 bar (87.02 psi) positive pressure.
• The pressure must not drop by more than 1 bar (14.5 psi)
during a test period of 3 minutes.
• Replace the brake master cylinder if the pressure decrease
is too high.

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. Hydraulic System 215

 Cautions & Warnings

Please read these WARNINGS and CAUTIONS before proceeding with maintenance and
repair work. You must answer that you have read and you understand these WARNINGS and
CAUTIONS before you will be allowed to view this information.

 If you lack the skills, tools and equipment, or a suitable workshop for any procedure described
in this manual, we suggest you leave such repairs to an authorized Audi retailer or other
qualified shop. We especially urge you to consult an authorized Audi retailer before beginning
repairs on any vehicle that may still be covered wholly or in part by any of the extensive
warranties issued by Audi.

 Disconnect the battery negative terminal (ground strap) whenever you work on the fuel system
or the electrical system. Do not smoke or work near heaters or other fire hazards. Keep an
approved fire extinguisher handy.

 Audi is constantly improving its vehicles and sometimes these changes, both in parts and
specifications, are made applicable to earlier models. Therefore, part numbers listed in this
manual are for reference only. Always check with your authorized Audi retailer parts
department for the latest information.

 Any time the battery has been disconnected on an automatic transmission vehicle, it will be
necessary to reestablish Transmission Control Module (TCM) basic settings using the Audi
Factory Approved Scan Tool (ST).

 Never work under a lifted vehicle unless it is solidly supported on stands designed for the
purpose. Do not support a vehicle on cinder blocks, hollow tiles or other props that may
crumble under continuous load. Never work under a vehicle that is supported solely by a jack.
Never work under the vehicle while the engine is running.

 For vehicles equipped with an anti-theft radio, be sure of the correct radio activation code
before disconnecting the battery or removing the radio. If the wrong code is entered when the
power is restored, the radio may lock up and become inoperable, even if the correct code is
used in a later attempt.

 If you are going to work under a vehicle on the ground, make sure that the ground is level.
Block the wheels to keep the vehicle from rolling. Disconnect the battery negative terminal
(ground strap) to prevent others from starting the vehicle while you are under it.
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 attempt to workwithon your
respect vehicle
to the if you
correctness do notinfeel
of information well. You
of
this document. increase
Copyright by AUDI the
AG. danger
injury to yourself and others if you are tired, upset or have taken medicine or any other
substances that may impair you or keep you from being fully alert.

 Never run the engine unless the work area is well ventilated. Carbon monoxide (CO) kills.

 Always observe good workshop practices. Wear goggles when you operate machine tools or
work with acid. Wear goggles, gloves and other protective clothing whenever the job requires
working with harmful substances.

 Tie long hair behind your head. Do not wear a necktie, a scarf, loose clothing, or a necklace
when you work near machine tools or running engines. If your hair, clothing, or jewelry were to
get caught in the machinery, severe injury could result.

Page 1 of 3
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other
intellectual property rights of Audi of America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of
this document may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,
nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the publisher.

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 Cautions & Warnings

 Do not re-use any fasteners that are worn or deformed in normal use. Some fasteners are
designed to be used only once and are unreliable and may fail if used a second time. This
includes, but is not limited to, nuts, bolts, washers, circlips and cotter pins. Always follow the
recommendations in this manual - replace these fasteners with new parts where indicated,
and any other time it is deemed necessary by inspection.

 Illuminate the work area adequately but safely. Use a portable safety light for working inside or
under the vehicle. Make sure the bulb is enclosed by a wire cage. The hot filament of an
accidentally broken bulb can ignite spilled fuel or oil.

 Friction materials such as brake pads and clutch discs may contain asbestos fibers. Do not
create dust by grinding, sanding, or by cleaning with compressed air. Avoid breathing
asbestos fibers and asbestos dust. Breathing asbestos can cause serious diseases such as
asbestosis or cancer, and may result in death.

 Finger rings should be removed so that they cannot cause electrical shorts, get caught in
running machinery, or be crushed by heavy parts.

 Before starting a job, make certain that you have all the necessary tools and parts on hand.
Read all the instructions thoroughly, do not attempt shortcuts. Use tools that are appropriate to
the work and use only replacement parts meeting Audi specifications. Makeshift tools, parts
and procedures will not make good repairs.

 Catch draining fuel, oil or brake fluid in suitable containers. Do not use empty food or
beverage containers that might mislead someone into drinking from them. Store flammable
fluids away from fire hazards. Wipe up spills at once, but do not store the oily rags, which can
ignite and burn spontaneously.

 Use pneumatic and electric tools only to loosen threaded parts and fasteners. Never use these
tools to tighten fasteners, especially on light alloy parts. Always use a torque wrench to tighten
fasteners to the tightening torque listed.

 Keep sparks, lighted matches, and open flame away from the top of the battery. If escaping
hydrogen gas is ignited, it will ignite gas trapped in the cells and cause the battery to explode.

 Be mindful of the environment and ecology. Before you drain the crankcase, find out the
proper way to dispose of the oil. Do not pour oil onto the ground, down a drain, or into a
stream, pond, or lake. Consult local ordinances that govern the disposal of wastes.

 The air-conditioning (A/C) system is filled with a chemical refrigerant that is hazardous. The
A/C system should be serviced only by trained automotive service technicians using approved
Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not
refrigerant recovery/recycling equipment, trained
permitted unless in related
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AG does not guarantee accept any liability
with regulations governing the discharging and
with respect disposal
to the correctnessof automotive
of information chemical
in this document. refrigerants.
Copyright by AUDI AG.

 Before doing any electrical welding on vehicles equipped with anti-lock brakes (ABS),
disconnect the battery negative terminal (ground strap) and the ABS control module
connector.

 Do not expose any part of the A/C system to high temperatures such as open flame.
Excessive heat will increase system pressure and may cause the system to burst.

Page 2 of 3
© 2018 Audi of America, Inc.
All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other
intellectual property rights of Audi of America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of
this document may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,
nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the publisher.

Version 2.0
 Cautions & Warnings

 When boost-charging the battery, first remove the fuses for the Engine Control Module (ECM),
the Transmission Control Module (TCM), the ABS control module, and the trip computer. In
cases where one or more of these components is not separately fused, disconnect the control
module connector(s).

 Some of the vehicles covered by this manual are equipped with a supplemental restraint
system (SRS), that automatically deploys an airbag in the event of a frontal impact. The airbag
is operated by an explosive device. Handled improperly or without adequate safeguards, it can
be accidentally activated and cause serious personal injury. To guard against personal injury
or airbag system failure, only trained Audi Service technicians should test, disassemble or
service the airbag system.

 Do not quick-charge the battery (for boost starting) for longer than one minute, and do not
exceed 16.5 volts at the battery with the boosting cables attached. Wait at least one minute
before boosting the battery a second time.

 Never use a test light to conduct electrical tests of the airbag system. The system must only
be tested by trained Audi Service technicians using the Audi Factory Approved Scan Tool (ST)
or an approved equivalent. The airbag unit must never be electrically tested while it is not
installed in the vehicle.

 Some aerosol tire inflators are highly flammable. Be extremely cautious when repairing a tire
that may have been inflated using an aerosol tire inflator. Keep sparks, open flame or other
sources of ignition away from the tire repair area. Inflate and deflate the tire at least four times
before breaking the bead from the rim. Completely remove the tire from the rim before
attempting any repair.

 When driving or riding in an airbag-equipped vehicle, never hold test equipment in your hands
or lap while the vehicle is in motion. Objects between you and the airbag can increase the risk
of injury in an accident.

I have read and I understand these Cautions and Warnings.

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Page 3 of 3
with respect to the correctness of information in this document. Copyright by AUDI AG.

© 2018 Audi of America, Inc.

All rights reserved. Information contained in this document is based on the latest information available at the time of printing and is subject to the copyright and other
intellectual property rights of Audi of America, Inc., its affiliated companies and its licensors. All rights are reserved to make changes at any time without notice. No part of
this document may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,
nor may these materials be modified or reposted to other sites, without the prior expressed written permission of the publisher.

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