Audi S6 Turn Signal & Electrical System Issues Decoded

Had the exact same issue on my 2018 Audi A6 TDI. As someone with moderate experience working on cars, I initially thought it was just a broken lens or simple bulb replacement needed for the indicator light. The symptoms were identical, warning lights, signal lamp issues, and error messages. After attempting basic troubleshooting, I took it to a workshop where they diagnosed a faulty connection in the wiring harness connected to the lighting control module. The signal lamp errors were actually a symptom of this larger electrical issue. The repair involved cleaning and reseating several plug connections, plus replacing one damaged connector. Total cost was 95 Euro including diagnostic time. The automotive lighting system has worked flawlessly since then. Before suggesting more specific solutions, could you share: Do all indicator lights malfunction or just one side? Are the errors constant or intermittent? Have you noticed any correlation with weather conditions? Did you recently have any work done on the electrical system? This would help determine if your issue matches what I experienced or might be something different.

Thanks for checking, my vehicle has 174618 KM on the odometer. After reading the previous messages, the electrical fault seems to be getting worse. The turn signal malfunction only affects the passenger side, and the errors appear out of nowhere, usually when starting the car. The warning messages in the instrument cluster are most frequent during damp weather. The automotive lighting system worked fine until last week. No recent work has been done on any electrical components. The signal lamp issues started suddenly while driving on the highway. Had the car serviced 2 months ago for routine maintenance, but nothing related to the electrical system was touched. A more concerning development is that now the indicator light sometimes flickers even when not activated. Given these symptoms, the wiring harness issue mentioned sounds very similar to what I am experiencing.

Thanks for the additional details. The flickering indicator light without activation definitely matches the symptoms I experienced before getting my A6 fixed. Since our vehicles are so similar, I am almost certain you are dealing with the same wiring harness connection issue. The correlation with damp weather is a telltale sign. In my case, moisture was getting into a damaged connector, causing intermittent signal lamp failures and triggering the error messages. The flasher relay would sometimes activate out of nowhere due to the faulty connection. Before the full repair, I tried a basic bulb replacement thinking it might solve the issue, but the problems persisted. The workshop found corrosion in the connector pins near the passenger side lamp assembly. They also discovered the wiring harness grommet had deteriorated, allowing moisture to reach the electrical connections. The complete fix included: Cleaning all connector terminals, Replacing the damaged wiring harness section, Installing a new grommet seal, Updating the lighting control module software Something to check: Look for any signs of water in the passenger side lamp housing. This could indicate where moisture is entering the system. Do not wait too long to address this. In my case, delaying the repair led to more extensive damage and higher costs. The initial estimate was 85 Euro, but waiting made it worse.

Thanks for the detailed response. Your diagnosis matches exactly what is happening with my car. I checked the passenger side lamp housing as suggested and found some condensation inside, that explains the correlation with damp weather. The turn signal issues and unusual flickering are really starting to worry me, especially since the indicator light problems are getting more frequent. The flasher relay acting up without being activated is particularly concerning. I will schedule a workshop visit this week to have them check the wiring harness and connections. Based on your experience, I will make sure they inspect the grommet seal and look for corroded connector pins. Better to fix it now before moisture causes more extensive electrical damage. The automotive lighting system on these cars seems quite sensitive to water intrusion. Hopefully a thorough cleaning of the connections and replacing any damaged parts will resolve these electrical gremlins. Will update once I get it checked out.