BMW 1 Series Multiple Cold Weather System Failures

Hey there! I've got some experience working on cars, and this sounds very familiar. I had a similar issue with my 2011 BMW 3 Series diesel (and previously owned a 5 Series too). The symptoms you're describing match exactly what I experienced. Turned out it was a faulty wire connection to the humidity sensor. My workshop found that the plug was corroded and wasn't making proper contact. The whole fix, including diagnostics, cost me 95 Euro, money well spent as it solved all those annoying issues at once. Before suggesting anything specific though, could you share: Your exact engine variant? Have you noticed any warning lights? When did these issues start occurring? Might help to narrow down if it's the same problem I had.

Thanks Mark for the feedback! I've got the 2.0L diesel variant, and these issues started about two weeks ago. No warning lights on the dash yet, just these annoying symptoms. My car's at 196230 KM, with the last service done just three months ago. What's interesting is that you mentioned the humidity sensor, my mechanic has been focusing on the fog sensor, but maybe they should look at the humidity sensor connections instead. Would be great if it's just a corroded wire like in your case. Did you notice any gradual deterioration of the symptoms, or did everything just stop working at once? Really appreciate your help on this!

Hey again! Oh wow, that's super interesting, my issues actually started pretty much the same way! Since we're both driving BMWs (mine was at around 180k when this happened), I can totally relate to your situation. In my case, the symptoms actually came on gradually over about a month. First, I noticed the windows getting foggy more often than usual, then the AC started acting up, and finally, the washer nozzles and mirror heating stopped working. My mechanic initially thought it was the fog sensor too, but after some digging, they found that corroded humidity sensor connection. Just a heads up, when they fixed mine, they actually found some moisture had gotten into the connector housing. The funny thing is, the humidity sensor was trying to compensate but couldn't get proper readings because of the bad connection. Classic case of one small issue causing multiple problems! Since your car's got similar mileage to what mine had, and you're experiencing identical symptoms, I'd bet good money it's the same issue. The lack of warning lights is also exactly like my situation, these sensor connection problems often don't trigger dash warnings. Tell your mechanic to specifically check the humidity sensor wiring harness and connector. It's worth looking at even if they're convinced it's the fog sensor. Trust me, you'll be glad you did! Let me know how it goes, really curious to hear if it's the same problem I had!

Thanks so much for the detailed response! You've really given me hope that this might be a simpler fix than initially thought. It's remarkable how similar our situations are, right down to the gradual onset of problems and the absence of warning lights. I just called my mechanic and mentioned what you said about the humidity sensor wiring harness and connector. He seemed quite interested in this angle, especially when I explained how it resolved identical issues in your BMW. He's agreed to check this first thing tomorrow morning. It makes perfect sense now that all these seemingly unrelated problems could be caused by one faulty connection. I'll definitely have them check for moisture in the connector housing too, that's a great tip. I'll update you once they've had a look at it. Really grateful for your help, you might have just saved me from a much more expensive repair job! Take care!