BMW M4 Climate Control Problems, Fog and Weak Heat Fix?

Hi there! I have some experience working on BMWs and faced a similar issue with my BMW M3 2016. The symptoms you're describing sound very familiar to what I dealt with on my car. In my case, it turned out to be a faulty cable connection to the climate control module. My workshop found that one of the main plugs had developed a poor connection over time, causing the system to malfunction. The repair cost me 95 Euro, including diagnostics and fixing the connection. Could you share more details about: When did these issues start? Are there any warning lights on the dashboard? Does the problem occur more during specific weather conditions? With this info, I can give you more specific advice based on my experience with both my M3 and what I know about the M4.

Thanks for the detailed response! Just had my service done last month at 151683 KM. My issues actually started about 3 weeks ago. No warning lights showing up on the dash, but I'm getting unusual climate control errors on the display screen. The fogging is definitely worse during colder mornings, especially after rain. When the car is running for about 15-20 minutes, the heating sometimes kicks in properly, but it's really inconsistent. The cable connection issue you mentioned sounds promising, did you notice any intermittent behavior like this before finding the loose connection? I'll definitely have the workshop check the connections when I take it in. Would hate to replace the entire module if it's just a connection problem like yours was.

Hey again! Thanks for those extra details about your M4. Yes, what you're describing sounds exactly like what I experienced with my M3! The intermittent behavior is what really rings a bell here, it's almost identical to what I dealt with. Before finding the loose connection, my heating would also work fine some days and then act up completely unusual on others. The inconsistency was super frustrating! I also noticed the same thing with it sometimes working better after the car had been running for a while, just like you mentioned. The morning fog issue was what actually led my mechanic to check the connections in the first place. He said these cables can get stressed over time from heat cycles and vibration, especially around the 150,000 km mark, which is right where your car is. One thing I learned through this, don't let them jump straight to replacing the whole module. Insist they thoroughly check all the connections first. My mechanic initially thought I needed a new module too, which would've cost a fortune! Might save you some serious cash. Quick tip: while you're waiting to get it checked, try running your AC for a few minutes before switching to heat, it helped reduce the fogging in my case as a temporary fix.

That's super helpful info, especially about running the AC first, I'll definitely try that trick tomorrow morning! Really relieved to hear your symptoms matched mine so closely. I've booked it in for next week and will definitely make sure they check all the connections before even thinking about replacing the module. You've saved me from stressing about potentially massive repair costs. Fingers crossed it's just the cable connection like yours was. I'll keep the mileage factor in mind too, makes total sense that these things start acting up around 150,000 km. Thanks again for sharing your experience with the M3, you've given me a much clearer direction on what to look out for. I'll update once I get it sorted!