2021-2026 Audi Driver Assist System Fault DTC C12D5FA

Owners of 2021-2026 Audi vehicles may encounter warnings related to their driver assist systems. These warnings, such as an "Audi adaptive light: system fault" or an "Audi pre sense: system fault", indicate that the vehicle's advanced safety features are temporarily unavailable. This technical service bulletin (TSB 2071958/1) addresses these specific conditions and provides a straightforward solution for an Audi driver assist fault.

Symptoms of an Audi Driver Assist Fault

Customers may observe one or more of the following messages displayed in the instrument cluster, indicating a temporary malfunction of the driver assist systems:

• "Audi adaptive light: system fault"
• "Audi pre sense: system fault"
• "Adaptive cruise assist: restricted"
• "Adaptive cruise assist: predictive control currently restricted"

It is important to note that these instrument cluster messages typically disappear after an ignition cycle, and the driver assist systems then function normally again. This suggests the issue is often sporadic rather than a persistent hardware failure.

Fault Codes / DTCs

When these symptoms occur, workshops will typically find a specific diagnostic trouble code (DTC) stored in the driver assist systems control unit -J1121- (address word 00A5). This DTC points to an issue with the image processing processor within the control module.

| Code | Description | Module | | :--- | :---------- | | C12D5FA | Driver assistance systems control module image processing processor not reacting (symptom number 221281) (passive/sporadic) | Driver assist systems control unit -J1121- (address word 00A5) |

Important Warning for Owners

Audi has issued a critical warning regarding this specific Audi driver assist fault:

"Do not replace any parts for this issue. Replacing parts does not solve this issue."

This means that technicians should not attempt to replace any components, such as the J1121 control unit, as this will not resolve the underlying problem and could lead to unnecessary costs. Claims for replaced parts may also be debited by warranty if this warning is not heeded.

Repair Procedure Summary

The recommended repair for this condition is simple and does not involve replacing any hardware. Technicians should connect to the vehicle's diagnostic system (ODIS) and delete the stored DTC C12D5FA. This action clears the fault code and restores normal operation of the driver assist systems.

Warranty Information

This service is covered under Audi's warranty for vehicles up to 48 months or 50,000 miles. For Certified Pre-Owned (CPO) vehicles, the claim type is G10, requiring verification of ownership. If the vehicle is outside of the specified warranty period, this Technical Service Bulletin serves as informational guidance. The relevant service codes for warranty claims are:

• Service Number: 9093
• Damage Code: 0039
• Diagnostic Time: GFF (0150 0000)
• Claim Comment: As per TSB 2071958/1

All warranty claims must adhere to the Audi Warranty Policies and Procedures Manual and are subject to review and audit by Audi Warranty.