BMW Climate Control Failure: Temp Sensor Mystery Solved

I have some experience working on BMWs and had a similar issue with my 2016 BMW 4 Series (my daily driver before switching to an X3). I ran into almost identical symptoms, climate control went haywire and temp sensor errors popped up. After taking it to my trusted workshop, they found it was a loose connection in the wiring harness going to the temperature sensor. The fix wasn't too complicated, they had to remove some trim pieces to access and repair the faulty connection, then recalibrate the system. Total cost was around 95 Euro and took about an hour. Could you share if you're getting any specific error codes? Also, does the fan still work at all when you try manual controls? This info would help determine if you're dealing with the same issue I had. Let me know those details and I can give you more specific advice on what to check.

Thanks for sharing your experience! I have similar mileage (95399 KM) and just had my service done last month. Yeah, the fan still works on manual, but it's super inconsistent. Sometimes it blasts full speed, other times barely any air comes out. Haven't checked the error codes yet, but that's a good suggestion. I've noticed the temperature reading on the display seems way off compared to what it actually feels like inside the car. I'll have my mechanic look at the wiring harness. Really hoping it's just a connection issue like yours and not something more serious! Did you notice any weird temperature readings before you got yours fixed?

Hey there again! Yeah, I totally remember having those exact same symptoms with my 2016 BMW 4 Series before I got it fixed. The temperature readings were completely off, sometimes showing like it was freezing inside when it was actually quite warm. Super annoying! What you're describing with the inconsistent fan behavior is exactly what I experienced too. Mine would out of nowhere go full blast then drop to almost nothing, just like yours. The wonky temperature readings were actually what made my mechanic check the wiring harness first. Just want to add, after they fixed mine, I had zero issues for the next 2 years until I traded it in for my X3. The calibration they did after fixing the wiring really made a difference. The whole system worked perfectly after that. Since you're at similar mileage to where I was when this happened (I was around 98000 KM), it's probably the same issue. It's pretty common for these connections to get loose over time with all the vibration from driving. Quick tip, when you take it in, ask them to check all the connectors in that area, not just the main temp sensor one. There are a few smaller connections that can cause similar issues. Better to get them all checked while they're in there. Let me know how it goes after you get it checked out!

Thanks so much for all the detailed info! This makes me feel way better about the situation. Just booked an appointment with my mechanic for next week and mentioned the wiring harness specifically. I'll definitely ask them to check all the connectors while they're at it, great tip! Really appreciate you sharing your long-term experience too. It's good to know the fix lasted for years without any issues coming back. The fact that you had such similar symptoms with the fan and temp readings makes me pretty confident this is the same problem. I was worried I might be looking at replacing the entire climate control system, so hearing it could just be a wiring issue is such a relief. I'll update you after the mechanic takes a look. Thanks again for all your help with this, you've saved me a lot of stress wondering what might be wrong!