Technical Service Bulletin
45 ABS/ESC control unit cannot be reached "DTC U012100 ABS Control Module no communication"
stored
45 24 40 2072977/2 March 22, 2024. Supersedes Technical Service Bulletin Group 45 number 24-39 dated
February 14, 2024 for reasons listed below.
Model(s)

Year

e-tron quattro

VIN Range

Vehicle-Specific Equipment

All

Not Applicable

2019
2021 - 2023

e-tron Sportback
quattro

2020 - 2023

e-tron S

2022 - 2023

Q8 e-tron, Q8
Sportback e-tron,
SQ8 e-tron, and
SQ8 Sportback
e-tron

2024

Condition
REVISION HISTORY
Revision

Date

Purpose

2

-

Revised Service (Updated procedure)
Revised Warranty (Updated Labor Operations)

1

02/14/2024

Initial publication

Customer states:
• There is reduced braking assistance and various warning lamps appearing in the instrument cluster.
Workshop findings:
• ABS/ESC Control unit -J104- (Diagnostic address 0003) cannot be reached in communication.
• The DTC "U012100 (Symptom Code 19875), ABS Control Module no communication" is also logged in the
diagnostic address 0001.

Technical Background
Control unit -J104- has performed a restart. After this, the electromechanical brake servo remains on the hydraulic
fallback level and no bus communication takes place. This results in driver messages from other vehicle systems
being displayed. This restart only occurs in very rare exceptional cases.

© 2024 Audi of America, Inc.
Internal

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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.

Technical Service Bulletin
Production Solution
Not applicable.

Service
Proceed as follows:
Vehicles equipped with ABS/ESC control unit -J104- with software version SW 2XX.
• Disconnect the 12V battery from the vehicle for 5 minutes and then check the accessibility of the control unit J104- in the diagnosis.
• Make sure the current software for the ABS control unit -J104- is at least version 242. (If the software level is
below 242, review if the vehicle is affected by Field Campaign 93N1 and proceed with the necessary updates
prior to moving to the next step).
• Release the parking brake.
• Perform a software update as described below.
• Follow all instructions in TSB 2011732: 00 Software Version Management (SVM), operating instructions.
• Update the ABS control unit (J104) using the SVM action code as listed in the table below, if necessary:
Model

Old Software
Part Number
4KE909059N

Old Software
Version
242

New Software
Part Number

New Software
Version

(or higher)

(or higher)

4KE909059N

245

SVM Code
Input

243
244

e-tron/Q8 e-tron
4KE909059G

242

03A036
4KE909059G

245

243
• Afterwards perform a Basic Settings of the Parking Brake and TPMS.
• If there are no DTCs stored in the ABS control unit -J104-, the vehicle can be released. If there are DTCs
stored in the ABS control unit, please follow GFF instructions.

Vehicles equipped with ABS/ESC control unit with software version SW321, please review: PSS
2073483: 45 PSS ABS/ESC control unit cannot be reached “DTC U012100 ABS Control Module no
communication” stored and follow instructions.

© 2024 Audi of America, Inc.
Internal

Page 2 of 3

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.

Technical Service Bulletin
Do not replace any component. Any control unit replacement for this concern may be denied.

Warranty
Claim Type:

• 110 Up to 48 Months/50,000 Miles.
• G10 for CPO Covered Vehicles – Verify Owner.
• If the vehicle is outside of any warranty, this Technical Service Bulletin is
informational only.

Service Number:

4545

Damage Code:

0040

Labor Operations:

Loosen and secure earth strap

9785 0999

10 TU

Check vehicle (bus sleep mode)

0689 0199

10 TU

Software Update (Includes checking for
DTCs)

0151 0000

Time stated on the
diagnostic protocol

Diagnostic Time:

(Max 50 TU)

Claim Comment:

Road test prior to the service procedure

No allowance

0 TU

Road test after the service procedure

No allowance

0 TU

As per TSB 2072977/2

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.

Additional Information
All part and service references provided in this TSB (2072977) are subject to change and/or removal. Always
check with your Parts Department and/or ETKA for the latest information and parts bulletins. Please check the
Repair Manual for fasteners, bolts, nuts, and screws that require replacement during the repair.©2024 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
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.

© 2024 Audi of America, Inc.
Internal

Page 3 of 3

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.