BMW 7 Series AUC Sensor & Blower Failure: Fix Needed

Hey there! I had a similar issue with my 2014 BMW 5 Series diesel last month. The symptoms you're describing match exactly what I experienced, funky smells and blower problems. Mine turned out to be more than just an AUC sensor fault. In my case, the mechanic found that the cable harness connecting to the blower motor had corroded and some wires were damaged. The connections had gotten loose over time, causing intermittent blower operation. They also discovered that the cabin air filter was completely clogged, which wasn't helping with those traffic smells. The repair included replacing the wiring harness and installing new connectors. It was actually a serious electrical issue that could have caused other problems if left unfixed. Not a quick fix, took the shop most of the day to sort it out properly. You'll want someone who knows BMWs well for this one. The ventilation system in these cars is pretty complex, and it's worth getting it diagnosed properly by a specialist. Best of luck with the repair.

Thanks so much for sharing your experience! That wiring issue sounds exactly like what might be happening with mine. The symptoms are spot on. Since it's been a little while since your repair, could you remember roughly how much you ended up paying to get it all sorted? Also, just wondering if you've had any other issues pop up since then? Really appreciate your help with this, trying to get an idea of what I'm in for.

Hey again! Great news, I just got my car back from the mechanic last week! Turns out it was exactly what we suspected from the AUC sensor fault. The fix was actually much simpler and cheaper than my previous repair experience that I mentioned before. They found a faulty cable connection to the AUC sensor which they were able to repair. Only cost me 95 € and it's working perfectly now, no more weird smells or blower issues. Much better outcome than my previous repair where they had to replace the whole wiring harness! Haven't had any problems since the fix. The ventilation system is working like new again and the blower's running smoothly. Such a relief it wasn't anything more serious this time around. Hope this helps give you a better idea of what you might be dealing with. Let me know how you get on with yours!

Thanks for the update! I actually just got my car fixed too and wanted to share my experience. Took it to a BMW specialist who was really thorough. They found a couple of damaged wires near the blower motor, plus the cabin filter was completely blocked. Fixed the wiring, replaced the filter, and checked all the connections. Total bill came to around 200 with parts and labor. The best part? No more funky smells in traffic, and the blower's working perfectly again! Such a relief it wasn't anything major. Been driving for about a week now with zero issues. Really appreciate everyone's advice here, helped me understand what I was dealing with and gave me confidence to get it sorted. Thanks again for sharing your experiences!