BMW i3 AUC Sensor Failure Causing Nasty Cabin Smells

Had the exact same problem with my 2018 BMW i8 Hybrid last winter. The AUC (Automatic Recirculated Air Control) sensor went bad on mine too. When I finally got it checked, turned out the main connector cable had corroded and lost contact with the sensor unit. The blower failure was actually a safety response to the faulty sensor readings. It wasn't a major repair, but definitely needed professional attention since it's tucked behind several components in the HVAC system. My fix required replacing both the sensor and the wiring harness. The mechanic also found some debris blocking the external air intake, which was contributing to the smell. Took about 3 hours to complete everything. Honestly, it's not something you want to ignore, bad air quality sensors can let in harmful exhaust fumes. I'd suggest finding a certified BMW technician for this one. Not the most complex repair, but needs proper diagnostic tools and expertise.

Thanks so much for sharing your experience! Glad to hear it wasn't a super complex repair. I'm curious, do you remember roughly how much the whole thing set you back? Also, has everything been working smoothly since the fix, or have you noticed any other quirks pop up? Really appreciate your help with this!

Hey again! Absolutely happy to help out! Actually, I just got my i8 back from the shop last week for this exact issue. Great news, everything's running perfectly now! The AUC sensor is working like a charm, and those nasty smells are completely gone. My repair was way simpler than I initially thought. Unlike my situation where I needed both sensor and wiring replaced, turns out you've got the same issue I had at first, just a dodgy cable connection. The mechanic only charged me 95 € to sort out the faulty connection, which was way less than I expected. Since the fix, the blower's back to normal and the air quality control is spot on. Haven't noticed any other issues at all, it's like having a brand new car again! The auto-recirculation is working exactly as it should, switching perfectly between fresh and recirculated air. If you're still on the fence about getting it fixed, I'd say definitely go for it. It's a relatively small investment for something that makes such a big difference to your driving comfort. Plus, you really don't want to mess around with potentially bad air quality in your car.

Thanks for all that detailed info about your repair! I actually bit the bullet and took my i3 to a different certified mechanic yesterday. You were spot on, it was a pretty straightforward fix. The mechanic found some gunk around the sensor connections and a bit of water damage that was causing the whole issue. Just got my car back today, and what a difference! No more funky smells, the blower's working perfectly, and that annoying error code is gone. The whole thing only cost me about 120 bucks, which honestly feels like a steal considering how worried I was initially. Really glad I didn't put this off any longer. The new mechanic was super professional and even showed me what was causing the problem. Can't believe I stressed so much about such a simple fix! Thanks again for helping me make the decision to get it sorted.