Cold-Running Subaru Stella Shows Multiple Warning Signs

Had similar symptoms with my 2014 Subaru Legacy 2.5i. The cold air problem turned out to be a failing electric auxiliary heater combined with a faulty temperature control module. The symptoms matched exactly: poor cold running, increased fuel consumption, and weak cabin heat. The blower motor was working, but the heating element wasnt activating properly during cold starts. This prevented the engine from reaching optimal temperature quickly, causing the higher fuel consumption. The repair involved replacing the complete PTC heater assembly and recalibrating the temperature control system. It was a substantial job requiring specialized diagnostic equipment, not something for DIY repair. The system needed proper programming after component replacement. A failing PTC heater is a serious issue since it affects both engine performance and cabin comfort. Would recommend getting those error codes read first, but be prepared for a workshop visit. The repair took almost a full day at the dealership service center. After fixing this, the cold starts improved dramatically and fuel consumption returned to normal. The cabin heating system now works as intended, providing proper heat within minutes of starting.

Thanks for sharing your experience with the Legacy heating system repair. Really helpful info since it sounds exactly like what Im dealing with. The HVAC system symptoms match perfectly, weak heat output and poor engine performance in cold weather. Quick question, do you remember roughly what the total repair cost was for the PTC heater replacement and programming? Also, has everything stayed working properly since the fix? Just want to get an idea what Im looking at cost-wise and if its likely to be a permanent solution.

Great news, got the repair done last week and can confirm the heating system is working perfectly now. The total came to 350€ for replacing the faulty electric auxiliary heater and programming the control module. The cold air problem is completely resolved. The engine performance has returned to normal and fuel consumption dropped back to expected levels. The heating element now kicks in properly during cold starts, and the cabin warms up quickly like it should. My mechanic mentioned these PTC heater repairs typically provide a long-term fix when done correctly. Since the repair, every cold start has been smooth and the heat not working issue is totally resolved. The blower motor delivers proper warm air within minutes now. While the cost might seem high, having a properly functioning heating system is worth it, especially during cold weather. Based on my experience, I'd say go ahead with the repair, it should solve your issues completely just like it did for mine.

Thanks for the input. Finally got the repair done last week and wanted to share my experience. Took it to a small independent workshop that specializes in electrical fault diagnosis. The mechanic confirmed the temperature control system was the culprit. Found a failing heating element and some wiring issues. Total repair cost was 420€ including parts and labor. The heating system now works perfectly, warm air comes through quickly and engine runs smoothly even on cold starts. Fuel consumption has dropped back to normal and those error codes are gone. The whole job took about 4 hours. Much better experience than my previous mechanic and the price seemed fair for the work involved. Really glad I checked here first, helped me understand the problem better before going in. Would definitely recommend getting this fixed promptly if anyone else notices similar symptoms with their heating system.