BMW 7 Series Fog Sensor Mystery Causing Multiple Issues

Hey there! I actually dealt with almost identical issues on my 2013 BMW 5 Series diesel last winter. Same symptoms, fog sensor problems, misting windows, and climate control acting up. After struggling with this for a couple weeks, it turned out to be a faulty wiring connection between the sensor and the climate control module. The mechanic found that moisture had gotten into the connector plug, causing corrosion. They had to replace the entire wiring harness for that section since the corrosion had spread. While it wasn't a major mechanical issue, it was really annoying because the whole climate system was unreliable. The repair wasn't quick, took them a full day because they had to remove several panels to access the wiring. For what it's worth, I haven't had any issues since they fixed it. It's definitely worth getting a second opinion from a different mechanic who specializes in BMW electronics. Hope this helps with your troubleshooting.

Thanks for sharing your experience. That sounds exactly like what I'm dealing with! Would you mind telling me roughly how much you ended up paying for the repair? Also curious if you've had any other electrical gremlins pop up since they fixed it? My last mechanic quoted me a crazy price, so I'm trying to get a sense of what's reasonable.

Hey again! Happy to report I got the fog sensor issue sorted! Took it to a BMW specialist and they found it was exactly what I suspected, a corroded cable connection. Total bill came to 95 Euro, which was such a relief after the crazy quote from my previous mechanic. The best part? Everything's working perfectly now. The windows don't fog up anymore, climate control is spot-on, and those annoying freezing spray nozzles are a thing of the past. Been about three months since the repair and haven't seen any other electrical issues pop up. Honestly, the repair was way simpler than my previous mechanic made it sound. They just had to clean up and fix the connection, no need for that whole wiring harness replacement they initially talked about. If you're still looking for someone to fix yours, definitely get a second opinion from a BMW specialist. These electrical gremlins can be tricky, but they don't always need expensive solutions. Let me know if you need anything else!

Thanks everyone for the feedback! Just wanted to update you all on what happened. Finally got my BMW fixed yesterday and wow, what a difference! Found this certified BMW specialist through a and I'm so glad I listened. The mechanic discovered it was indeed a corroded wire connection, just like you mentioned. They cleaned it up, replaced a small section of the wiring, and everything's working perfectly now. The whole thing cost me way less than expected, around 120 Euro for parts and labor. Such a relief after that ridiculous quote from my previous mechanic! Drove home with clear windows, working climate control, and properly functioning spray nozzles. No more dealing with foggy windows during my morning drives. The mechanic also showed me exactly what was wrong and explained how to spot early signs of similar issues. Really appreciated their transparency. Guess sometimes you just need to find the right mechanic for the job. Thanks again for steering me in the right direction, saved me quite a bit of money and headache!