Audi TT Cruise Control Failure, Common Fix Guide

I had a similar issue with my 2019 Audi A5, and after some troubleshooting, it turned out to be fairly straightforward to fix. Having some experience with basic car maintenance, I first checked the brake light switch since that often interferes with cruise control operation. However, the real culprit was a loose connection in the wiring harness leading to the steering wheel controls. My workshop found that the cable connection to the cruise control module had worked itself loose over time, causing intermittent failures. The repair involved properly securing and reconnecting the wiring, plus a system reset. Total cost was 95 Euro for diagnostics and repair. Before jumping to conclusions though, could you share: Have you noticed any other electrical issues? Does the brake light function normally? Are there any specific error codes stored? Have you had any recent work done on the steering wheel or column? This information would help determine if youre dealing with the same issue I had or if its something else entirely.

Thanks for sharing your experience. The last service was at 12000KM and the current mileage is 13019KM. Since then, I noticed the throttle position sensor light briefly flashing on the dashboard before the cruise control stopped working. I havent had any other electrical issues, and the brake lights are working fine. The error code is P0578, which keeps showing up even after clearing it. No recent work has been done on the steering wheel or related components. I will have the wiring checked as per your suggestion, but I am starting to think it might be related to the sensor issues.

Thanks for the additional details. That throttle position sensor warning light actually makes this situation quite different from my initial diagnosis. In my case with the A5, it was purely a wiring issue, but your P0578 code combined with the flashing sensor light suggests a more specific problem. After seeing similar symptoms in my car months after the initial wiring fix, I learned that the throttle position sensor can indeed cause cruise control failures. The dashboard light flashing before the system failed is a telling sign, something I wish I had mentioned earlier as a potential warning indicator. The error code P0578 typically indicates a cruise control switch correlation issue, but in my experience, this can also be triggered by a faulty throttle position sensor sending incorrect signals to the control module. When this happened to my A5, replacing the throttle position sensor resolved both the warning light and the cruise control functionality. The repair cost for my throttle position sensor replacement was around 280 Euro, including diagnostics. Given your low mileage, this might even be covered under warranty. Before heading to the workshop, you might want to have them specifically check: Throttle position sensor connections, Speed sensor functionality, Cruise control module inputs, Electrical ground connections These components often work together, and a fault in one can trigger error codes that seem unrelated.

Thanks for the detailed suggestions. After reading about your similar experiences, I decided to take my TT to the dealer since its still under warranty. The technician confirmed the throttle position sensor was failing, which caused the cruise control system to disable itself as a safety measure. They also found a minor issue with the clock spring in the steering wheel that needed adjustment. The good news is both issues were covered under warranty. The dashboard light is now gone and the cruise control works perfectly after the sensor replacement and clock spring adjustment. This matches what you mentioned about the sensor being the likely culprit when the warning light appears before cruise control failure. For anyone else facing similar issues, definitely check if the throttle position sensor light appears before the cruise control stops working, seems to be a common connection between these systems that isnt immediately obvious.