BMW X7 Climate Control Nightmare: AUC Sensor Gone Bad?

Hey there! I went through something very similar with my 2019 BMW X5 last year. I have some experience working on cars, but mostly basic maintenance stuff. The symptoms you're describing sound exactly like what I dealt with. My workshop found that the AUC sensor's wiring connection had worked itself loose over time, causing both the blower issues and the unwanted air intake. The fix was pretty straightforward, they had to replace a faulty connector and properly secure the wiring. Cost me around 95 Euro and solved both problems completely. Could you share how long you've been having these symptoms? Also, what's your mileage? And did you notice if it started happening after any specific event (like a car wash or heavy rain)? These details would help me understand if you're dealing with the exact same issue I had with my X5. The X series seems prone to these AUC sensor connection issues, but it's usually a pretty quick fix once diagnosed correctly.

Thanks for sharing your experience! Really helpful. My car has only done 11870 KM and had its latest service about two months ago. The issue started gradually over the past couple of weeks, and I haven't noticed any connection to specific events like rain or car washes. It's reassuring to hear your fix was relatively straightforward and affordable. I'm starting to think it might be the same connector issue since the symptoms match up perfectly. Will definitely mention this to my service advisor when I take it in. Did your car throw any other warning lights besides the AUC error code?

Hey again! Yeah, in my case, there weren't any other warning lights, just that AUC error code. With such low mileage on your X7 (mine had about 45000 KM when the issue cropped up), you're definitely still under warranty, so the repair should be covered. The gradual onset matches what I experienced too. It started with occasional funky smells, then the blower became more and more temperamental before finally giving up. Since you mentioned it started after a recent service, you might want to have them check if something was accidentally knocked loose during the maintenance work. One thing I forgot to mention in my first reply, after they fixed mine, they also did a quick system adaptation procedure with their diagnostic tool to make sure everything was properly calibrated. Make sure they do that for yours too, as it seems to prevent the issue from coming back. It's been over a year now, and I haven't had any similar problems since. Let me know how it goes with the service center. I'm curious if it turns out to be the same connector issue!

Thanks so much for all this detail! It's super helpful to know about the system adaptation procedure, I'll definitely make sure to ask about that when I take it in. You're right about the warranty too, that's a relief. I'll schedule an appointment with my service center tomorrow and mention everything you've shared, especially about checking if anything got disturbed during the recent service. Really appreciate you taking the time to explain your experience so thoroughly. I feel much more confident now about what to expect and what to ask for. I'll update this thread once I get it sorted out. Thanks again for all your help with this!