2025 Audi Q5 Headlight Defective Warning TSB 2078609/2

Owners of certain 2025 Audi Q5 and SQ5 models may encounter an intermittent warning message in their instrument cluster stating, "Left/right main beam headlight defective. See owner's manual." This issue, identified by Audi Technical Service Bulletin (TSB) 2078609/2, is primarily a software-related concern.

Despite the warning, there are typically no functional restrictions or performance issues with the main beam headlights. The warning lamp may disappear after cycling the ignition but can reappear intermittently during driving. This TSB provides a solution to permanently resolve the 2025 Audi Q5 headlight defective C12FC01 issue.

Symptoms

The primary symptom is the appearance of a yellow warning message in the instrument cluster while driving. The exact message displayed is: "Left/right main beam headlight defective. See owner's manual." This warning may not be constant; it can appear intermittently, sometimes disappearing after the vehicle's ignition is turned off and then on again, only to reappear later. Crucially, even with this warning, the main beam headlights usually continue to function without any noticeable performance degradation.

Fault Codes / DTCs

When this condition occurs, diagnostic scans will typically reveal specific fault codes stored in the vehicle's event memory. The key diagnostic trouble code (DTC) associated with this issue is C12FC01. This code is often accompanied by details such as "LED channel 4, electrical fault" and "symptom 139272." These entries are logged in diagnostic address 0029, which pertains to the Left light control module, and/or diagnostic address 0039, which relates to the Right light control module.

Diagnosis / Trigger Conditions

Technicians can reproduce the customer's complaint by observing the warning message in the instrument cluster. The definitive diagnosis involves checking the vehicle's event memory for the specific entries: C12FC01 LED channel 4, electrical fault, and symptom 139272. These codes confirm that the issue is present within the light control system, even if the headlights appear to be working correctly. The intermittent nature of the warning is a key characteristic that helps identify this particular software-related fault.

Technical Background

Audi has determined that the root cause of the "Left/right main beam headlight defective. See owner's manual" warning and associated DTC C12FC01 is a software issue. This means the problem is not due to a faulty hardware component in the headlight system but rather an anomaly in the vehicle's control unit programming that incorrectly triggers the warning message.

Repair Procedure Summary

The resolution for the 2025 Audi Q5 headlight defective C12FC01 warning involves performing a software update. This Technical Service Bulletin (TSB) 2078609/2 instructs technicians to carry out TSB 2077960, which details a combined software update. The specific software version required for this fix is 03.01.00/C (28.11.01) KD1**. This update is designed to correct the software anomaly that causes the erroneous warning message. It's important to note that this TSB 2078609/2 supersedes and replaces a previous bulletin, PSS 2078182, which also addressed a similar warning lamp issue in the instrument cluster.

Important Warnings

If your vehicle is outside of its warranty period, this Technical Service Bulletin is provided for informational purposes only. This implies that any associated repair costs may not be covered by Audi. Owners should consult with their dealership regarding warranty coverage for this specific software update.

Warranty Information

For vehicles covered under warranty, Audi provides specific codes for processing claims related to TSB 2078609/2. The Service Number for this repair is 9407, and the Damage Code is 0039. The labor operations involved include a software update, which covers the flat rate for the update, bus sleep cycle, adaptation drives, and additional work, identified by labor operation code 0151 0040 and allocated 50 Technical Units (TU). Additionally, charging the battery, labor operation code 2706 8950, may be required. All warranty claims must adhere to the guidelines outlined in the Audi Warranty Policies and Procedures Manual.

TSB Revision History

This Technical Service Bulletin has undergone revisions to ensure accuracy and completeness. The initial publication, Revision 1, was released on August 18, 2025. A subsequent update, Revision 2, revised the title to include the DTC C12FC01 and updated the service verbiage to provide clearer instructions for technicians.

NHTSA ID: 11023788