BMW Auxiliary Heater Dead: DIY or Mechanic Needed?

I had a similar issue with my 2018 BMW 5 series diesel last winter. The glow plug control module was defective, causing the auxiliary heater to fail completely, no response, just like yours. Initially thought it was just a blown fuse, but diagnostic showed multiple error codes. Took it to a different garage than my usual one, since they specialize in BMW diesel systems. The issue was quite serious, the faulty control module had caused one glow plug to burn out completely, and it was starting to affect the others. They had to replace the control module and two glow plugs. The job took about 4 hours, and they also cleaned the entire glow plug system while they were at it. Been working perfectly since then, even in cold starts. These heater systems are pretty complex in modern diesels, so it's worth finding someone who really knows their stuff. Hope this helps point you in the right direction.

Thanks for sharing your experience. That's really helpful as it sounds exactly like what I'm dealing with. Been worried about ending up with more serious damage if I leave it too long. Quick question, do you remember roughly how much the whole repair set you back? And has everything stayed working properly since then, or have you noticed any other quirks with the heating system?

Hey there! Happy to give you an update. Just got my car back actually, took it to that specialist BMW shop I mentioned and they sorted it out completely. The whole auxiliary heater system is working perfectly now. Turns out I was right about the glow plug being the culprit, they found one completely shot and had to replace it. The bill came to 440 € in total, which honestly wasn't as bad as I was expecting given how complex these systems are. And to answer your other question, everything's been running like clockwork since the repair. No more cold start issues, heater kicks in exactly when it should, and the engine's running smoother overall. A word of advice, if you're still having similar symptoms, don't wait too long to get it checked. These things can snowball and cause bigger problems if left alone. The shop I went to really knew their stuff with BMW diesels, made all the difference compared to my previous experiences.

Thanks for the detailed follow-up! Finally got my car sorted yesterday. Took your advice and found a BMW specialist mechanic through a. You were spot on, it was definitely the glow plug system causing trouble. The mechanic found two faulty glow plugs and a worn-out control module. Repair cost was a bit higher than yours at 580 €, but they did a thorough job. They cleaned the entire system and even spotted a minor wiring issue they fixed while they were at it. The heater's working beautifully now, first time in weeks I've had proper heat during cold starts! Really glad I didn't put this off any longer. The mechanic mentioned I could've ended up with engine damage if I'd kept driving it like that. Thanks again for pushing me to get it checked out properly. Sometimes paying a bit more for someone who knows what they're doing really pays off in the long run. Case closed on this one, just in time for the cold weather too!