Technical Service Bulletin
27 48V vehicle electrical system warning, DTC U046900 stored in the ECM
27 24 65 2058831/12 January 18, 2024. Supersedes Technical Service Bulletin Group 27 number 23-64 dated
December 22, 2023 for reasons listed below.
Model(s)

Year

A6, A7, A8, and
Q8

2019 – 2023

A6 allroad, and
Q7

2020 – 2023

S8

2020 – 2022

A8 e quattro

2020 – 2021

VIN Range

Vehicle-Specific Equipment

All

48V electrical system

Condition
REVISION HISTORY
Revision Date

Purpose

12

Revised Service (Updated Notices for clarity)

-

Revised Additional Information (Updated reference TSB documents)
11

12/22/2023 Revised Service (Updated verbiage to match ODIS tester)

10

12/13/2023 Revised title (Updated for clarity)
Revised header (Updated DTCs)
Revised Condition (Added image, updated Workshop findings, and added note)
Revised Technical Background (updated statement)
Revised Service (updated TSB instructions)
Revised Warranty (updated Labor Operations)
Revised Additional Information (included links to reference TSB documents)

Customer states:
• The message “Electrical system: Malfunction. See owner’s manual” is displayed on the instrument cluster
(Figure 1).
• A yellow or red battery warning symbol is displayed on the instrument cluster.

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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
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Technical Service Bulletin

Figure 1. Cluster Warning Message.
Workshop findings:
The following DTC is stored:
ECM, J623 (address word 0001), or Gateway, J533 (address word 0019):
• DTC U046900: Invalid data received from starter/generator control module (symptom 36564).

The DTC and symptom must match for this TSB to apply.

Technical Background
The Belt Starter Generator (BSG), together with the vehicle’s 48V system is an intelligent vehicle system that
provides electrical power to the vehicle as needed. Therefore, traditional diagnosis methods, like expecting the
alternator to output at full voltage any time the vehicle is running, are no longer viable, as the output power of the
BSG is regulated according to the current requirements of the vehicle.
For further information, please refer to TSB 2067906: 27 48V Reference: diagnosis and system information.
A hardware related issue may cause the belt starter generator (BSG) to stop working as intended.

Production Solution
Not applicable.

Service
Prior to following the diagnostic instruction:
• VAS tester with the current version of ODIS is installed.

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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
• While diagnosing the 48V system ensure the 48V and 12V battery are charged properly prior to following the
procedure, please refer to TSB 2067906: 27 48V Reference: Charging 48V Battery with 12V Charger DTC
P0A7D00.
Performing the function test “C29 – Check_Erase” and attach to the test plan:
ODIS path for Q7:
• Body
• Electrical system
• 01 - On Board Diagnostic capable systems
• CC - starter-alternator -C29
• CC - Functions
• 00CC – Check/erase event memory entry
ODIS path for A6/A7/A8/Q8:
• Diagnostic capable system
• 00CC - starter alternator -C29
• 00CC - Functions
• 00CC – Check/erase event memory entry
When asked “Are you running this program based on an instruction in a Technical Service Bulletin (TSB)?”,
answer the test plan with YES.
If the following event memory entry is shown in ODIS, replace the starter-alternator according to ETKA and
reevaluate the concern:
• B200096 – Faulty control module (Figure 2).

A screenshot of ODIS with the VIN and DTC Memory Results from the test plan is necessary for billing
under warranty.

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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

Figure 2. ODIS tester screen.

If the listed DTC is not stored in the test plan, then the generator is not faulty and replacing parts will
not fix the problem.

Warranty
Claim Type:

• 110 up to 48 Months/50,000 Miles.
• G10 for CPO Covered Vehicles – Verify Owner.

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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
• 1-GW for vehicles that fall under the Starter-Alternator Limited Warranty
Extension.
Service Number:

2726

Damage Code:

0040

Labor Operations:

Replace starter-alternator (If required
according to this TSB.)

2726 XXXX

See SRT with
associated
operations

Diagnostic Time:

GFF

0150 0060

Time stated on
the diagnostic
protocol
(Max 100 TU)

Road test prior to the service procedure

No allowance

0 TU

Road test after the service procedure

No allowance

0 TU

(Includes time to ensure 12V and 48V
batteries are charged.)

Claim Comment:

As per TSB 2058831/12

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
The following Technical Service Bulletin(s) will be necessary to complete this procedure:
• TSB 2067906: 27 48V Reference: Charging 48V Battery with 12V Charger DTC P0A7D00
• TSB 2067937: 27 48V Reference: diagnosis and system information
All part and service references provided in this TSB (2058831) 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.

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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.