SQ7 PTC Heater Issues Trigger Cold Start Problems

I experienced similar heating system problems with my Q8 50 TDI from 2017. The electrical fault in the heating element caused exactly these symptoms, rough cold starts and higher fuel consumption. The temperature control system uses the PTC auxiliary heater to assist engine warm-up and cabin heating, especially crucial in diesel engines. When it fails, the engine management compensates by injecting more fuel during cold starts, explaining the increased consumption. The diagnosis revealed a defective heating element in the HVAC system. This required removing parts of the dashboard to access the heater assembly. The repair involved replacing the complete PTC heater unit since individual elements cannot be serviced separately. This was a serious issue requiring specialized diagnostic equipment. The repair took two full days at the shop due to the complex disassembly needed to access the heating system components. After replacement, both the cold start behavior and fuel economy returned to normal. Without repair, continuous operation risks further damage to related components and keeps putting extra stress on the engine during cold starts.

Thanks for sharing your experience. I had a nearly identical issue on my 2019 SQ7. Heat not working properly, terrible fuel consumption and those awful cold starts. Really glad I got it fixed because the symptoms were getting worse each week. The repair fixed everything in my case and has been running perfect for the last 6 months. The PTC heater replacement made a huge difference, cold starts are smooth again and fuel consumption is back to normal. Did you happen to track the repair costs? Would be interesting to compare since prices seem to vary quite a bit. Also curious if you noticed any other issues pop up since the heating element was replaced?

Since having the PTC heater replaced at my dealer, the heating system has worked flawlessly. The repair cost came to 350 Euro which covered both parts and labor. This resolved all the electrical fault issues with the heating element I mentioned earlier. The cold air problems completely disappeared after the fix. Cold starts are now perfectly smooth and fuel consumption dropped back to normal levels. No other issues have surfaced in my HVAC system since the repair was completed. The investment was definitely worth it, as running with a faulty auxiliary heater could have led to more expensive problems down the line. For anyone experiencing similar symptoms, I strongly recommend getting the heating element checked and replaced if needed, rather than waiting for potential complications.

Thanks for the input. Went to my mechanic last week and got the PTC heater replaced. The whole repair took about 8 hours and cost me 420 Euro. The electrical fault was exactly what you all described. The temperature control is working perfectly now. My mechanic found the HVAC system had some buildup around the heating element which made the replacement a bit trickier than usual. They had to clean everything thoroughly before installing the new unit. The cold starts are finally smooth again and fuel consumption has dropped significantly. Really glad I got this fixed before winter, no more freezing cold air in the cabin during startup. Best thing is the check engine light is finally off and the car feels like new again. No other issues have come up since the repair. If anyone else runs into similar heating system problems, definitely worth getting it checked out right away.