2021-2025 Audi Q7/Q8/SQ7/SQ8/RS Q8 DTC C129700

Owners of 2021-2025 Audi Q7, Q8, SQ7, SQ8, and RS Q8 vehicles may encounter warning messages in their instrument cluster related to the suspension or roll stabilization system. This issue is addressed by Audi Technical Service Bulletin (TSB) 2067804/4, which supersedes TSB Group 40 number 24-72 dated January 18, 2024. The bulletin provides a detailed procedure for diagnosing and resolving the underlying fault.

Symptoms

Drivers may observe one or both of the following messages displayed in the instrument cluster:

• "Air suspension fault"
• A message concerning the "roll stabilization/suspension"

These warnings indicate a potential problem with the vehicle's active roll stabilization system, which is crucial for handling and ride comfort. If you see these messages, it's important to have your vehicle inspected.

Fault Codes / DTCs

The primary diagnostic trouble code (DTC) associated with this issue is:

• C129700 (symptom code 12664851): This code indicates a function limitation due to a malfunction within the sway control module. It is typically logged in one of the two roll stabilizer control units, J924 or J1096, which correspond to diagnostic addresses 00D4 or 00D5.

If your vehicle logs Audi Q8 DTC C129700, it points directly to the active roll stabilization system as the source of the problem.

Diagnosis and Trigger Conditions

Before proceeding with any repair, technicians are instructed to ensure no other relevant DTCs related to the suspension or roll stabilization are present. If only the C129700 DTC is logged, the diagnostic process involves a specific sequence to reset the system and attempt to clear the fault:

1. Unplug the diagnostic connector from the vehicle.
2. Switch off the ignition.
3. Lock the vehicle (ensuring doors, hood, and rear lid are closed).
4. Wait until the vehicle enters bus sleep mode.
5. Unlock the vehicle.
6. Plug the diagnostic connector back into the vehicle.
7. Switch on the ignition.
8. Attempt to erase the DTCs.

Important Warnings for Owners and Technicians

This TSB includes a critical instruction: when performing the "Replace Control Module" step on roll stabilization control units J924 and J1096 with the ODIS tester, do not physically replace the control unit. The procedure is a software-based reset or reconfiguration, not a hardware replacement.

Furthermore, technicians are advised to reproduce the customer complaint to ensure it can be clearly assigned to this TSB. The repair should only be carried out if all criteria—including model/type, VIN number, engine/motor and gearbox code, PR number(s), part number(s), and software version—apply exactly. Failure to adhere to these criteria may result in the problem not being resolved and could lead to rejected warranty claims and re-debiting of parts.

Repair Procedure Summary

After the initial diagnostic steps and attempting to erase DTCs, the core repair involves using the ODIS tester. Technicians must perform the "Replace Control Module" step for both roll stabilization control units J924 and J1096. As noted, this is a software-level operation and does not require replacing the physical control unit.

If the Audi Q8 DTC C129700 persists after these steps, the technician must then follow the instructions provided in Guided Fault Finding (GFF) within the ODIS system to further troubleshoot and resolve the issue.

Warranty Information

This service bulletin provides specific codes for warranty claims:

• Service Number: 4024
• Damage Code: 0040

Labor operations associated with this repair include:

• Charge battery: 2706 8950 (See SRT for associated operations)
• Check vehicle (BUS Sleep mode): 0689 0199 (10 TU)
• Diagnostic Time (GFF): 0150 0000 (Time stated on the diagnostic protocol)
• Road test prior to the service procedure: No allowance (0 TU)
• Road test after the service procedure: No allowance (0 TU)

All warranty claims must comply with the Audi Warranty Policies and Procedures Manual and are subject to review by Audi Warranty. If the vehicle is outside of its warranty period, this Technical Service Bulletin serves as informational guidance only.

NHTSA ID: 11009336