BMW 3 Series Hybrid Multiple System Failures, Sensor Issue?

Hey there! I had a somewhat similar issue with my 2018 BMW 5 Series Hybrid last winter (I also own a BMW X3). I have some experience working on cars, but nothing too advanced. The symptoms you're describing sound very familiar. My car showed multiple electrical gremlins all at once, climate control acting up, dead mirror heaters, and wonky sensors. Turned out it wasn't the fog sensor itself, but a damaged wiring harness connector that was causing all these issues. My trusted mechanic found that moisture had gotten into one of the main connector plugs, causing corrosion and poor connections. The fix involved cleaning the connector, replacing some damaged pins, and properly sealing it. Total cost was around 95 Euro, mostly labor since the actual parts were minimal. Before I can give more specific advice, could you share: Any specific error codes you're getting? When did these issues start appearing? Have you noticed any pattern when the problems occur (like during wet weather)? This might help narrow down if you're dealing with the same issue I had.

Thanks for sharing your experience! Mine's at 59556 KM since my last service, and I'm getting the exact same symptoms. Just got error codes P0420 and P0443, which started popping up last week during that really wet spell. Haven't spotted any clear pattern yet, but I've noticed the issues get worse early in the morning when there's more moisture in the air. Good to know about the wiring harness connector, that's really helpful and definitely sounds like it could be the same problem. I'll mention this to my mechanic when I take it in. The cost seems reasonable too, much better than what I was worried about! Did you have any issues after the repair was done?

Hey again! Yeah, I can totally relate to those morning issues, that's exactly how mine started too. After my repair, everything's been working perfectly for about 8 months now. Those error codes you mentioned (P0420 and P0443) are actually different from what I had, but the symptoms are spot on the same. Just to update you on my experience, since the repair I mentioned before, I've put another 20,000 km on my BMW and haven't had a single problem with any of those systems. The moisture-related problems completely disappeared after they fixed that connector. The morning fog issues, frozen nozzles, all of it, gone. One thing I'd recommend though, get them to check all the connectors in that area, not just the obvious one. My mechanic found a second connector that was starting to show early signs of corrosion, and we preventively cleaned and sealed that one too. Might save you another trip down the line. The only thing I ended up doing differently was getting some extra weatherproofing applied to those connectors. Cost me a bit more, but totally worth it for the peace of mind. Would you like me to share what specific weatherproofing they used? It might be worth asking your mechanic about it.

Thanks for the detailed follow-up! That's really reassuring to hear everything's been working well for 8 months after your repair. I'll definitely ask about checking all the connectors and getting that extra weatherproofing done, seems like a smart preventive measure. Yes, please let me know what weatherproofing they used! I want to mention it specifically to my mechanic when I take the car in tomorrow. Even if the error codes are different, the matching symptoms make me pretty confident it's a similar issue. Really hoping it'll be a straightforward fix like yours was. I was worried I'd be looking at a massive repair bill, but this sounds much more manageable. Just need to get through these foggy mornings until I can get it sorted! Thanks again for all your help, this kind of real-world experience is exactly what I was looking for when I posted.