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Technical Service Bulletin

Topic 47 Thermal deformation on vacuum line to brake servo

Market area United States 444 Volkswagen of America, Inc. (6444)

Brand Audi

Transaction No. | 2078475/1

Level EH

Status Released for publishing

Release date Jul 3, 2025

New customer code

Object of complaint

Complaint type

Position

chassis -> brakes, brake regulation -> foot brake -> service brake
braking effect

functionality -> no function

>no
instruction <

information, navigation, communication, entertainment -> indicator
display symbols -> parking brake indicator display

functionality -> activates

chassis -> brakes, brake regulation -> foot brake -> service brake
braking effect

component, automotive
fluids -> too soft

>no
instruction <

information, navigation, communication, entertainment -> malfunction
display symbols -> parking brake malfunction display

functionality -> activates

chassis -> brakes, brake regulation -> brake booster

functionality -> no function

chassis -> brake system -> brake pedal

component, automotive
fluids -> too hard

chassis -> brakes, brake regulation -> brake booster

functionality -> operation
sequence incorrect

chassis -> brakes, brake regulation -> foot brake -> service brake
braking effect

component, automotive
fluids -> too little

>no
instruction <

information, navigation, communication, entertainment -> indicator
display symbols -> driving dynamics regulation (ESC) indicator display

functionality -> activates

information, navigation, communication, entertainment -> warning
display symbols -> parking brake warning display

functionality -> activates

chassis -> brakes, brake regulation -> brake booster

functionality -> decreasing

chassis -> brakes, brake regulation -> anti-lock braking system (ABS)

functionality -> no function

information, navigation, communication, entertainment -> warning
display symbols -> brake failure waming display

functionality -> activates

chassis -> brakes, brake regulation -> foot brake -> service brake
braking effect

functionality -> irregular

>no
instruction <

information, navigation, communication, entertainment -> malfunction

display symbols -> ABS malfunction display

functionality -> activates

Vehicle data
Audi A8

Sales types

Type|MY |Brand| Designation} Engine code |Gearbox code | Final drive code
AN* |2025|A * * *
AN* |2024|/A * * *
A4N* |2023|A * * *
AN* |2022|A * * *
4N* |2021|A * * *
4N* |2020|A * * *

PR numbers

PR numbers
?:with D65

Documents

Document name

master.xml

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Technical Service Bulletin Transaction No.: 2078475/1
47 Thermal deformation on vacuum line to brake servo Release date: Jul 3, 2025
Condition

Customer states:

There may not necessarily be a customer complaint for this TSB. The customer may see a warning about the brake
system, or an increased pedal force may be necessary.

Workshop findings:

The complaint can be reproduced. Thermal deformation is identified on the vacuum line to the brake servo. The line
diameter is decreased due to this deformation.

Technical Background
Excessive heat is generated in the engine compartment.

The function of the brake system is ensured as the vacuum supply has a redundant design. The ABS is also
available to provide backup support when braking.

Production Solution

Gradual introduction from June 2025 onwards.

Service

Please replace the affected vacuum line and also install part 4NO612169.

Warranty
Claim Type: * — If the vehicle is outside of any warranty, this Technical Service Bulletin is
informational only.

Service Number: 477TT

Damage Code: 0010

Labor Operations: Replace vacuum line for brake servo 4777 5599 |See SRT with
associated
operations

Claim Comment: As per TSB 2078475/1

All warranty claims submitted for payment must be in accordance with the Audi Warranty Policies and Procedures
Manual. Claims are subject to review or audit by Audi Warranty.

Please note the information on predecessors and items that are included and excluded in the repair operations, as
well as any associated tasks.

Required Parts and Tools

The part numbers mentioned in this TSB are different than the ones listed in ETKA. Only use parts listed in this
TSB, this includes superseding part numbers!

Part Number

Part Description

Quantity

See ETKA

Fasteners, Bolts, Nuts, and Screws as needed per the Repair Manual

See ETKA/ELSA

4NO0 612 169

Heat reflective mat

01

Additional Information

All parts and service references provided in this TSB (2078475) are subject to change and/or removal.

©2025 Audi of America, Inc. All rights reserved. The 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
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