RS6 Cold Start Issues Linked to PTC Heater Failure

Had similar symptoms with an Audi S4 2007. The electrical fault in the PTC auxiliary heating element caused cold start issues and increased fuel consumption. The heating element helps warm up the engine faster in cold conditions, and when defective, the HVAC system compensates by running rich fuel mixture. The blower motor kept working but no warm air was coming through. After diagnosis, it turned out the PTC heater failed completely, affecting engine temperature management. This is a serious issue that needs professional attention since it impacts both engine performance and interior comfort. The repair required replacing the complete heating element assembly and updating the control module. Cold starts improved immediately after the fix, and fuel economy returned to normal. The check engine light cleared once the new heating element was properly integrated with the system. Based on the symptoms and mileage described, strongly recommend getting it checked by an Audi specialist. Continuing to drive with a faulty heater can lead to increased engine wear and fuel system issues.

Thanks for sharing that experience. I had identical cold start troubles with my RS6 last winter. Got it fixed at a specialized workshop and it runs perfectly now. The PTC heater replacement resolved both the rough idle and high fuel usage completely. Been 6 months since the repair and no issues whatsoever. Just curious, do you remember roughly what you paid for the complete fix? Also wondering if you noticed any other electrical gremlins popping up before or after the heater problems?

Glad the repair worked out well for you too. The total bill came to 350 Euro for replacing the defective electric auxiliary heater, which is pretty standard for this type of work. The HVAC system has been working flawlessly since the fix. I did notice the temperature control acting up a few weeks before the main heater problem, sometimes the heat not working properly or taking longer to warm up. But once the PTC heater was replaced, all those minor electrical issues disappeared completely. The blower motor and entire heating system have been running perfectly for over a year now. The investment was worth it, considering how much extra fuel the car was burning before the repair. Plus, having reliable heat during cold starts makes a huge difference in engine performance and comfort.

Thanks for the input. I finally took it to an independent Audi specialist who diagnosed and fixed the heating system issue. The total repair cost was 380 Euro, a bit more than expected but worth every cent. The mechanic showed me the old PTC heating element which was completely burned out. No wonder the engine was running so rough on cold starts. They also found and fixed a loose connection in the blower motor wiring while doing the heater repair. Its been running perfectly for 2 weeks now, starts smoothly even in cold weather and fuel consumption is back to normal. Really happy I got it sorted before winter. The new workshop did a much better job than my previous experience, and I actually learned a lot about how the heating system works in these cars.