RS3 Cold Start Issues Linked to Faulty PTC Heater

I dealt with a similar heating system issue on my 2018 S3. The symptoms matched yours exactly, rough cold starts and the HVAC system acting up, particularly during initial startup. With some experience working on these models, I knew it likely involved the auxiliary heater. The blower motor would run but barely any heat came through. After checking error codes, my workshop confirmed the electric auxiliary heater was defective. The repair involved replacing the PTC heating element and testing the electrical connections. Total cost was 350 Euro including parts and labor. The fix completely resolved both the cold start roughness and heating problems. Fuel consumption returned to normal levels too, since the engine wasnt struggling to compensate for the faulty heater. To help diagnose your specific case, could you share: Current mileage, When the symptoms first appeared, Whether the check engine light is on, Any other electrical issues youve noticed, Specific error codes stored This information would help confirm if youre dealing with the same electrical fault I experienced. The repair is straightforward but requires proper diagnosis first.

After checking the codes again at 196536 KM, my check engine light came on this morning. The electrical fault definitely seems to match what you described. The symptoms started about two weeks ago when temperatures dropped. The stored fault codes are P2463 and P0301. The heat not working properly during cold starts is my biggest concern, and the engine feels particularly rough for the first few minutes. No other electrical issues noticed so far, but the HVAC system takes much longer than usual to warm up. Thanks for sharing your repair costs. That gives me a good reference point for what to expect at the workshop.

Based on those fault codes and symptoms, sounds like exactly what I dealt with on my S3. The P0301 misfire code combined with the P2463 DPF code during cold starts strongly points to the PTC heating element failing, just like in my case. The cold air issues and rough running during startup are classic signs of a faulty heating system, especially since it coincided with colder weather. When the auxiliary heater fails, it puts extra strain on the engine during warm-up, leading to those misfires you're experiencing. After getting my heating element replaced, the cold start behavior improved immediately. The engine ran smoother from startup and the HVAC worked normally again. Your mileage is similar to when mine failed too. The electrical fault triggering your check engine light matches the sequence I saw, it started intermittent then became constant. Getting it fixed sooner rather than later is smart since a failing heater can impact other components if left too long. One tip: make sure they check all the electrical connections during repair. Sometimes corrosion at the connectors can contribute to heating system failures. The full diagnostic and repair should run close to what I paid, assuming no other issues are found.

The codes and cold start symptoms you described definitely align with my situation. Our mileage is very close too, which makes sense for when these heaters typically fail. The rough running and cold air issues during startup have gotten worse this past week. Just scheduled a workshop appointment for next week. They quoted 380 Euro for the PTC heating element replacement and electrical fault diagnosis, so pretty close to what you paid. Hopefully fixing the heating system will resolve both the cold start behavior and HVAC warm-up delays. Will update once the repair is done to confirm if it solves the misfire codes and fuel consumption issues. Really glad you shared your experience, saved me from potentially replacing wrong parts while trying to fix the cold start problems. Thanks for the tip about checking the electrical connections too. Will make sure they inspect those during the repair since the heating system troubles seemed to start right when temperatures dropped.