BMW M4 Cabin Odor Linked to Blower Motor Failure

Hey there! I have some experience with cars and had a very similar issue with my 2016 BMW M3. The symptoms were almost identical, cabin odors and blower problems. Took it to my trusted workshop and it turned out to be a loose connection between the AUC sensor and its wiring harness. They found the plug was slightly corroded too. The whole repair, including diagnostics and fixing the connection, cost me 95 Euro. After that, everything worked perfectly again, no more smells, and the blower was back to normal. Since you're dealing with a similar BMW platform, it could be the same issue. However, I'd need to know: Has the check engine light come on? Are you getting any other warning messages? Did this start suddenly or develop gradually? This info would help determine if you're facing the exact same problem I had. Just a heads up, don't wait too long to get it checked. Having proper ventilation is crucial, and these issues can sometimes lead to bigger problems if left unattended.

Thanks for sharing your experience! My check engine light hasn't come on, but I do get a "Check Control Message" about the automatic air circulation. The issue started gradually over the past few weeks. At first, I thought it was just regular traffic fumes, but it's definitely getting worse. I've kept up with all maintenance (last service was at 38312 KM), so it's frustrating to have this pop up. Good to know about the potential wiring issue, that sounds like it could be the culprit, especially since it's way less expensive than replacing the whole sensor unit. I'll get it checked out this week. Better safe than sorry, and I definitely don't want to risk any bigger problems developing from this.

Hey again! Just wanted to follow up since your symptoms sound exactly like what I experienced. The gradual onset and that specific Check Control Message, it's like déjà vu from my M3 situation. Honestly, good call on planning to get it checked this week. When my issue started, I also thought it was just normal traffic smells at first. The fact that you're getting that warning message about the auto air circulation is pretty much identical to what I saw before discovering my wiring issue. Since you mentioned your recent maintenance, I'm even more convinced it could be that connector/wiring problem I had. These things sometimes just happen with age, regardless of how well you maintain the car. The corrosion on my connector developed despite regular servicing too. Quick tip though, when you take it in, make sure they check the entire wiring harness while they're at it. After my repair, my mechanic mentioned he found a couple of other connections that were starting to show early signs of wear. Getting those cleaned up at the same time probably saved me from future headaches. Keep us posted on what they find! Always curious to know if these BMW quirks follow the same patterns.

Thanks so much for all the detailed follow-up info! Just got back from scheduling an appointment with my mechanic, and I made sure to mention everything about the wiring harness and connectors you talked about. They seemed to agree it's likely similar to your situation. Really appreciate the tip about having them check the whole wiring harness, definitely wouldn't have thought to ask about that. It makes total sense to prevent future issues while they're already poking around in there. Your experience has been super helpful in making me feel less worried about this whole thing. I was initially concerned it might be something major, but now I'm pretty optimistic it's just that connector issue. I'll update the thread once I get it fixed, hopefully with good news about a simple, affordable repair like yours! Thanks again for taking the time to share your experience. It's exactly the kind of real-world feedback I was hoping for when I posted this question.