Audi TT Seat Heater Fix: Common Failure Revealed

As someone with moderate experience in automotive repair, I encountered a very similar heating element issue with my 2013 Audi A5. The symptoms were identical, complete heater failure in the driver's seat with error codes showing up. After initial diagnosis, my workshop found that the seat heating mat was defective. The thermal sensor was no longer communicating properly with the temperature control unit. They had to replace the entire heating mat assembly, which was integrated into the seat cushion. The repair took about 3 hours, and the total cost came to 390 Euro, including parts and labor. Since then, the seat heating has worked flawlessly, providing consistent warmth without any error codes. To help provide more specific guidance for your case, could you share: Which seat is affected (driver, passenger, or both)? Are you getting any specific error codes? Did the issue start suddenly or gradually? Does the seat show any signs of wear or previous repairs? These details would help determine if your TT is experiencing the same common heating element failure that affects several Audi models from that generation.

I have exactly 50202 KM on the clock, and the seat warmer issue affects only the drivers side. The initial diagnosis showed error code B109845. It started gradually over the past month, first working intermittently before failing completely. I managed to test the voltage at the connector under the seat, which shows power is reaching the heating element. This suggests the seat heater wiring may not be the culprit, pointing more toward a faulty heating element in the cushion itself. Given the common heating element failures mentioned, I will have the workshop focus on checking the seat heating mat and thermal sensor connection first. The seat is all original with no previous repairs or visible wear. Thanks for sharing your repair experience. Knowing a similar fix cost around 390 Euro helps set realistic expectations for the upcoming workshop visit.

Based on your description and voltage test, this definitely sounds like the same thermal sensor failure I experienced with my A5. The gradual deterioration pattern and error code match exactly what happened in my case. The fact that power reaches the connector but no heat is produced confirms my suspicion about the heating mat assembly. These temperature control systems often fail in a similar way across the Audi lineup from that era, especially in the driver seat which gets the most use. Since completing the heating repair on my car, I learned that the thermal sensor malfunction is quite common in these seat warmer systems. The workshop explained that the connection between the sensor and the temperature control unit can degrade over time, leading to the exact symptoms you describe. For reference, my repair included: Complete heating mat replacement, New thermal sensor installation, System recalibration Total labor time was about 3 hours, though costs may have changed since my repair. The key is ensuring they install the updated version of the heating mat assembly, which has improved durability. The good news is that after the repair, you should have reliable seat heating performance again. Consider having them check the passenger side sensor connections while they are at it, as preventive maintenance could save money in the long run.

Thanks for the detailed information about the thermal sensor and heating mat assembly. The error code B109845 seems to match the common seat heating failures reported in similar Audi models. I appreciate knowing your A5 repair details since it gives me a clear picture of what to expect. The voltage test I did helps confirm this is likely a thermal sensor or heating mat issue rather than a wiring problem. Since my TT has 50202 KM and the failure pattern matches yours, gradual deterioration starting with intermittent function, I feel more confident about the diagnosis. I will schedule the workshop visit next week and have them focus on replacing the heating mat assembly and thermal sensor in the seat cushion. The 390 Euro cost reference is helpful for budgeting. I will also take your advice about checking the passenger side temperature control components preventively. The automotive repair should be straightforward since this seems to be a documented issue. Will update once the seat heating is fixed. Thanks for helping me narrow down the problem before taking it to the shop.