2025-2026 Audi A5/Q5 Drive System Fault TSB 2079998/3

Audi has issued Technical Service Bulletin (TSB) 2079998/3 to address a specific "drive system fault" that may appear in the instrument cluster of certain 2025-2026 Audi A5, S5, Q5, and SQ5 models. This bulletin, released on December 18, 2025, provides a solution for customers experiencing this warning, which is often linked to specific diagnostic trouble codes (DTCs) related to the gearbox electronics.

This TSB supersedes PSS TSB 2078847 and highlights that the primary fix for the Audi A5 drive system fault is a combined software update. It's crucial for owners to be aware of this bulletin, as it outlines the proper diagnostic and repair procedures for this condition.

Revision History

Technical Service Bulletin 2079998/3 has undergone several revisions to ensure accuracy and completeness:

• Revision 1 (November 10, 2025): Initial publication of the bulletin.
• Revision 2 (November 10, 2025): Revised the condition description and corrected instructions.
• Revision 3 (December 18, 2025): Revised the header to add model years and updated warranty information, including labor operations.

Symptoms Owners May Notice

Owners of affected 2025-2026 Audi vehicles may observe the following symptom:

• "The drive system fault warning lamp lights up in the dash panel insert."

In some cases, there might not be a direct customer complaint, but the fault codes are found during routine service or in connection with other issues. The primary indication for the driver is the illumination of the warning lamp, signaling a potential Audi A5 drive system fault.

Fault Codes / DTCs

When a "drive system fault" is present, technicians may find one or both of the following event memory entries (DTCs) logged in the gearbox electronics control unit J217, specifically at diagnostic address 0002:

Code	Description	Symptom Number
P071100	"Transmission Fluid Temperature Sensor "A" Circuit Range/Performance"	20756
P270800	"Solenoid Valve 6 is sticking on"	20859

These codes indicate specific issues within the transmission system that trigger the overall Audi A5 drive system fault warning, pointing to potential problems with the transmission fluid temperature sensor or a solenoid valve.

Diagnosis and Trigger Conditions

To properly diagnose the issue and ensure it aligns with TSB 2079998/3, technicians are instructed to try and reproduce the customer complaint. This helps confirm that the observed symptoms and logged DTCs precisely match the conditions described in the bulletin. The repair procedure should only be carried out if all criteria, including model/type, chassis number, engine/motor, gearbox code, PR number(s), part number, and software version, are met. Failure to do so may not resolve the problem and could lead to repeat repairs or warranty claim rejections. It is also important to check if TSB 2079690, "00 Combined software update 03.10.00/C (28.13.01) KD2," is applicable to the specific vehicle, and if so, its described software update should be performed.

Repair Procedure Summary

The recommended repair for the Audi A5 drive system fault involves performing a combined software update. This update is designed to optimize the vehicle's software, specifically for the gearbox electronics control unit J217, to prevent the fault from occurring. The process includes:

1. Connecting a battery charger: This ensures stable voltage during the software update process.
2. Performing the software update: This is a fixed-rate operation that includes all necessary preliminary and follow-up work, such as bus sleep cycle management and calibration drives. The specific service number for this operation is 3730, with a damage code of KD02.
3. Labor Operations:
   • 0151 0010: Software update, including connecting the battery charger (refer to SRT for associated operations).
   • 0151 0040: Fixed rate for software update, including all required preliminary and follow-up work (bus sleep cycle, calibration drives, additional work), allocated 130 time units (TU).
   • 0150 9999: For additional attempts due to flash cancellation, an additional lump sum of 50 time units per documented attempt is possible.

When performing the combined software update, time stamps are not required for billing under warranty, allowing technicians to work on other vehicles simultaneously. This combined software update can also be performed by non-productive personnel.

Important Warnings for Owners

Owners should be aware of the following critical information regarding this software update and their vehicle's warranty:

• Warranty Coverage: If your vehicle is outside of its warranty period, this Technical Service Bulletin 2079998/3 is for informational purposes only. All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual. Claims are subject to review or audit by Audi Warranty.
• Chip Tuning: If your vehicle's engine control unit software has been modified by chip tuning, you must inform the dealer. Updating the engine control unit software will render chip tuning ineffective. In certain circumstances, the engine control unit may even be damaged by the software update. Audi advises that you clarify with the tuning company in advance whether a software update is possible. Damage to the engine control unit resulting from chip tuning cannot be billed to AUDI AG under warranty. Neither AUDI AG nor the dealership can be held responsible for damage caused by the software update or for damage that occurs as the result of not having the update performed. It is crucial to make a note to this effect on the repair order before it is signed by the customer and include this information in the customer file.

Owner Action

If you own a 2025-2026 Audi A5, S5, Q5, or SQ5 and experience the "drive system fault warning lamp lights up in the dash panel insert" or suspect your vehicle may be affected by the P071100 or P270800 DTCs, you should schedule an appointment with an authorized Audi service center. The service center will diagnose the issue and perform the necessary combined software update as outlined in TSB 2079998/3. This service is typically covered under warranty if your vehicle qualifies.

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Source: NHTSA ID: 11027421, Transaction No.: 2079998/3