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Rennadler

BMW 7 Series Cold Start Issues: Diagnosis Needed

Fault stored

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Engine noise when cold

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Poor fuel economy

Hey all! Having some concerns with my 2008 BMW 7 (53k km, gas engine) and wondering if anyone has dealt with similar issues. The car's taking forever to warm up, runs rough when cold, and I'm burning through more fuel than usual. There's also a check engine light. I suspect it might be the PTC heater, but after a bad experience with my last mechanic, I'd love to hear from others who've had these symptoms. Did you get it fixed? What was the actual problem? Any recommendations for handling this? Thanks in advance!

4 comment(s)


AlexSch

I had similar symptoms with my 2005 BMW 5-series last winter. Initially thought it was just the cold weather, but the check engine light and rough idle were concerning. Took it to my mechanic and you're right about suspecting the PTC heater, that's exactly what it was in my case. The auxiliary heater had failed and wasn't supporting the engine warm-up properly. The diagnosis showed the heating element was completely burnt out. It wasn't just affecting comfort; it was making the engine management system run a richer fuel mixture to compensate, hence the higher fuel consumption. It turned out to be a serious issue that needed immediate attention because it was affecting multiple systems. The repair involved replacing the entire PTC heater unit and reprogramming the control module. The car runs perfectly now, warms up normally, idles smoothly, and fuel consumption is back to normal. Based on the symptoms you've described, I'd definitely get it checked out soon. These issues tend to worsen and could potentially lead to more complications if left unaddressed.

Rennadler (Author)

Thanks for sharing your experience! That sounds exactly like what I'm dealing with. Really helpful to know it was the PTC heater in your case. Can't remember if you mentioned, do you recall roughly how much the repair set you back? Also, has everything been running smoothly since the fix, or have you noticed any other issues pop up? Been a bit worried about potential related problems that might show up later.

AlexSch

Hey there! Happy to update you on this. Yes, since my last post I can confirm the PTC heater repair has been absolutely spot on. Had to shell out 350 € for the fix, which included replacing the faulty electric auxiliary heater and some programming work. I know it might sound a bit steep, but considering how much better the car runs now, it was totally worth it. Everything's been running like a dream since the repair, no kidding! The car warms up properly now, idles perfectly smooth (even on those really cold mornings), and my fuel consumption is back to what it should be. No more check engine light either, which is a relief. And to answer your question about related issues, nope, haven't had a single problem since. It's been several months now, and the car's performing exactly as it should. Seems like catching and fixing the PTC heater issue early prevented any knock-on problems. My mechanic really knew their stuff on this one! Let me know if you need any other details. Sounds like you're dealing with exactly what I had, so hopefully this helps with your decision!

Rennadler (Author)

Thanks so much for all the info! Actually, I bit the bullet and took my car to a mechanic yesterday. You'll never believe it, turns out my situation was different from what I expected. The mechanic found a cracked vacuum line and a faulty coolant temperature sensor. Makes sense why it was acting similar to your PTC heater issue though! The repair was pretty straightforward. Got it all fixed up for about 200 bucks. Much better than I was fearing! The mechanic was great too, really took the time to explain everything and even showed me the damaged parts. Such a relief after my last bad experience with repairs. Car's running like new now. Started right up this morning with no rough idle, and the engine warning light is finally off. Guess sometimes it pays to stop worrying and just get it checked out properly. Really appreciate everyone's help and advice on this one, helped me get the courage to just take it in!

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