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Technical Service Bulletin

94 Warning lamp for exterior lighting displayed in instrument cluster: DTC U112100,

U110B00, B126A29

Transaction No.: 2074786/3

Release date: Dec 11, 2025

Condition
Model{s) Year(s) VIN Range Vehicle Specific Equipment
A3, $3, RS 3, Q4 e-tron, .
and Q4 Sportback e-tron 2022 -2024 All Not applicable
REVISION HISTORY
Revision Date Purpose
3 - Revised Service (updated procedure)
Revised Warranty (Updated warranty table)
2 09/26/2025 | Revised Condition (Updated DTC verbiage)
Revised Production solution (Updated sw and part number index)
1 08/01/2024 | Initial publication
Customer statement:

Awanrning lamp for the exterior lighting or adaptive light is displayed in the instrument cluster. The lighting system
appears to be working as it should.

This phenomenon occurs only very occasionally.

Pressing the “AUTO” button on the light switch module remedies the fault immediately and causes the warning lamp

to go out.

Workshop findings:

The concern can be reproduced. The following DTCs are stored in the onboard supply control unit J519 (address

0009):

* DTC B126A29 Light switch implausible signal
* DTC U112100 Data bus missing message.
* DTC U110B00 Light switch no communication.

All lighting functions are working.

[O}

Documentation required

Technical Background

Software issue

Production Solution
Depending on vehicle type, new light switch with optimized software 0013 and new part index AC,AD.

Service

This TSB Closes PSS 20373612: 94 PSS Headlight warning in cluster, DTC : B126A29, U110B00 stored in 09
module.

Check whether the situation is as described above.
Pressing the “AUTO” button will cause the warning lamp to go out and the DTC entry to change to intermittent.
The DTC can then be deleted.

If it is not possible to delete the DTC and the entry remains logged as static, the light switch must be replaced.

If only DTC “U110B00 Light switch no communication” is stored without the other entries, the cause may be
a loose connector, a pin that has been pushed back or a wiring problem.

When billing, please always attach photos that clearly show the complaint to DOC-IT. To ensure a reference to the
vehicle, the image(s) must:

« — Include the VIN and date.
* Must not be edited.
* Should be in focus and taken with sufficient light. A high resolution is not necessary.

If appropriate, please mark the location of the problem so that parts analysis has a clear reference to the complaint.
Please ensure that the photo documentation does not show any people and/or faces, license plates, or customer
data.

Warranty

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

* Replace and repair labor operations cannot be claimed together. Only bill according
to what was needed.

Service Number: 9405

Damage Code:

0040

Labor Operations:

Replacing light switch (only if DTC cannot be cleared)

Remove and install main light switch 9405 19xx See SRT with
associated
operations

GFF / Guided Functions 0150 0060 Labor according to

the diagnostic log

Repairing light switch (only if replacing the switch is not necessary)

Repair light switch 9405 4199 Bill according to the
time required

GFF / Guided Functions 0150 0010 See SRT with
associated
operations

GFF / Guided Functions 0150 0060 Labor according to

the diagnostic log

Claim Comment:

As per TSB 2074786/3

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 parts and service references provided in this TSB (2074786) are subject to change and/or removal.

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