2025 Audi A5 / S5 Steering Warning Lamp TSB B200042

Audi has issued Technical Service Bulletin (TSB) 2079733/3 to address a steering control module fault affecting certain 2025 Audi A5 and S5 vehicles. This bulletin, released on January 28, 2026, outlines a specific software issue that can lead to a warning lamp illumination and diagnostic trouble codes. If you are experiencing the Audi A5 steering warning B200042, this information is relevant to your vehicle.

Symptoms

Owners of affected 2025 Audi A5 and S5 vehicles may observe "The yellow steering warning lamp lights up in the instrument cluster after a software update / workshop visit." This visual warning indicates a potential issue with the steering system's control module. If you experience the Audi A5 steering warning B200042, it's important to have your vehicle inspected.

Fault Codes / DTCs

During diagnosis, technicians may find the following diagnostic trouble code (DTC) logged in diagnostic address 0044:

• DTC B200042 - Control module faulty, with symptom 5243138 or 13631746.

These codes specifically point to a control module fault related to the steering system.

Technical Background

Audi has identified the root cause as a software issue concerning the internal memory layout within the steering control module. This internal software anomaly can lead to the system incorrectly flagging a fault, resulting in the Audi A5 steering warning B200042.

Repair Procedure Summary

To resolve the steering control module fault and the associated warning lamp, a software update is required. The repair procedure involves performing a software update described in a separate bulletin, TSB 2079690, specifically referencing "00 Combined software update 03.10.00/C (28.13.01) KD2".

It is crucial to connect a battery charger to the vehicle during this process to ensure stable voltage throughout the software update. The update procedure encompasses all necessary preliminary and follow-up work, which includes managing the bus sleep cycle and performing calibration drives. This comprehensive update aims to optimize the internal memory layout and prevent the recurrence of the fault.

Production Solution

Audi implemented an optimization of the internal memory layout in production vehicles from specific dates onward to prevent this issue in newer models. This includes:

• Audi A5 FU from September 2, 2025, onward
• Audi A6 FN from August 29, 2025, onward
• Audi Q6 e-tron GF from September 10, 2025, onward
• Audi A6 e-tron GH from September 18, 2025, onward

Warranty Information

For vehicles still under warranty, this repair is covered. The claim type is informational only if the vehicle is outside of any warranty. The service number for this operation is 4835, with a damage code of KD02.

Labor operations for this TSB include:

• 0151 0010: Software update, including connecting a battery charger. Refer to the Standard Repair Time (SRT) for associated operations.
• 0151 0040: Fixed rate for software update, including all required preliminary and follow-up work (such as bus sleep cycle, calibration drives, and additional work), allocated 130 time units (TU).
• 0150 9999: In the case of additional attempts after a flash abort occurred, an additional lump sum of 50 time units can be claimed per flash cancellation, with 50 TU per each documented attempt.

The claim comment for this procedure is "As per TSB 2079733/3". All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review or audit by Audi Warranty. When performing the combined software update, time stamps are not required for billing under warranty, allowing technicians to work on other vehicles simultaneously. This update can also be performed by non-productive personnel.

Important Revision History

This TSB has undergone several revisions:

• Revision 3: Revised header, adding Model & Software Level information.
• Revision 2 (December 18, 2025): Revised the Condition section, adding the model table and revision history. Also, the Warranty section was revised to update labor operations.
• Revision 1 (October 22, 2025): Initial publication of the bulletin.

Additional Information

All part and service references provided in this TSB (2079733) are subject to change and/or removal. Always check with your Parts Department and/or ETKA for the latest information and parts bulletins. Additionally, please consult the Repair Manual for any fasteners, bolts, nuts, and screws that require replacement during the repair.

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Source: NHTSA ID: 11028458, TSB ID: 2079733/3