VW Passat Cold Start Issues: Failed PTC Heater Fix

I encountered almost the exact same issue with my 2017 VW Golf diesel. Having some experience with diesel engine troubles, I recognize these cold start symptoms well. The PTC heater failure caused similar problems, rough cold starts, heat not working properly, and increased fuel consumption. My check engine light also came on, indicating an electrical fault in the heating system. After multiple cold starts with temperature control issues, I took it to my regular workshop. They ran a complete diagnostic which confirmed the auxiliary heater was defective. The entire repair, including parts and labor, cost 350€. The repair process involved: Full system diagnostic scan, Testing the PTC heater resistance values, Checking all related electrical connections, Replacing the faulty electrical auxiliary heater unit, Clearing fault codes and testing The cold start issues disappeared completely after the repair, and fuel consumption returned to normal. Before suggesting more specific solutions, could you share: What error codes are showing up in your scan? Does the cabin heat work normally once the engine warms up? Have you noticed any changes in battery performance? How long does the rough running last after cold starts? This information would help determine if your issue matches what I experienced.

Just had my last service at 126180km and the mechanic confirmed similar symptoms. The blower motor and temperature control were working fine, but the electrical fault was definitely linked to the heating element in the PTC heater system. My codes were P0670 and P0671, suggesting a control module issue. Once the mechanic replaced the glow plug control module and PTC heater assembly, the cold start problems resolved completely. Total repair cost was 420€. The whole diagnosis and repair took about 4 hours. Worth mentioning the fuel consumption dropped back to normal after fixing it, was using about 0.8L more per 100km during the issue.

Thanks for sharing those details about your repair experience. Interesting that we had such similar issues with our VWs. The P0670/P0671 codes you mentioned match exactly what my HVAC system was showing before the repair. Just like in your case, my fuel consumption also spiked by roughly 0.7-0.8L/100km while the PTC heater was faulty. After my repair, the cold start behavior improved immediately and the fuel economy returned to normal. One thing I learned from my experience, the blower motor can test fine even when the PTC heater itself is failing. The heating element is really the critical component that affects cold start performance. My repair also involved the control module, which seems to be a common failure point in these systems. Good to hear you got it fixed properly. The 420€ repair cost sounds about right, slightly more than what I paid but prices for these parts tend to fluctuate. The 4-hour repair time matches my experience too, as they need to access several components in the HVAC system.

Just had my last service at 126180km and the mechanic confirmed similar symptoms. The blower motor and temperature control were working fine, but the electrical fault was definitely linked to the heating element in the PTC heater system. My codes were P0670 and P0671, suggesting a control module issue. Once the mechanic replaced the glow plug control module and PTC heater assembly, the cold start problems resolved completely. Total repair cost was 420€. The whole diagnosis and repair took about 4 hours. Worth mentioning the fuel consumption dropped back to normal after fixing it, was using about 0.8L more per 100km during the issue. Thanks for confirming your similar experience. The repair cost was a bit higher in my case, but getting rid of those cold start issues and fixing the electrical fault made it worthwhile. Fuel savings alone will help offset the repair cost over time.