BMW M4 Multiple Sensor Issues, Temp Controls Dead

Hey there! I have some experience working on BMWs. Had a similar issue with my 2019 BMW M3 last year. The symptoms you're describing sound very familiar, I had the exact same problems with the temp display, AC, and heating features. After taking it to my regular workshop, they found it was just a faulty wiring connection to the temperature sensor module. Some cables had worked loose and weren't making proper contact. The fix was pretty straightforward, they replaced the connection assembly and recalibrated the system. Cost me around 95 Euro total, which wasn't too bad considering I was worried it might be something major. Before I can give more specific advice, could you tell me if you're getting any specific error codes? Also, when did these issues start happening, was it sudden or gradual? This info would help confirm if you're dealing with the same problem I had. BTW, I mentioned the M3 since I know these models share a lot of similar components and electronics.

Thanks for sharing your experience! Mine has 139938 KM and just had its service last month. I'm getting error code 0x394B22 consistently. The issues started quite suddenly, was fine one morning, then everything just stopped working on my drive home. Haven't noticed any warning signs before that. Good to hear it might just be a wiring issue rather than a complete sensor failure. That repair cost sounds way better than what I was worried about. Did you notice any other electrical quirks before getting it fixed? Like unusual warning lights or system resets?

Hey again! Yeah, I can totally relate to that sudden failure, it's exactly how mine went down too. Similar mileage as well, mine was at about 132,000 KM when it happened. Interesting that you're getting that specific error code. When mine failed, I got the same code (0x394B22), which definitely points to the same wiring connection issue I had. And yeah, just like yours, mine also went from perfectly fine to completely dead during a single drive. Actually, now that you mention warning lights, I did notice something I forgot to mention in my first reply. About a week before the total failure, my iDrive system would occasionally show a brief temperature reading error, but it would disappear so quickly I didn't think much of it. Did you happen to notice anything like that? The fix really was straightforward in my case, took the workshop about an hour to sort it out. Just make sure they check the entire wiring harness while they're in there. My mechanic found some slight corrosion on other nearby connections and cleaned those up too, just as preventive maintenance. One thing though, after the repair, it took about three start-stop cycles for all the systems to fully normalize. So don't panic if everything doesn't work perfectly right after the fix. The system just needs a bit of time to recalibrate itself.

Thanks so much for that detailed follow-up! Actually, come to think of it, I did notice that same quick temperature error flash on my iDrive a few times last week. I just brushed it off since it disappeared so fast, but now it makes total sense as an early warning sign. Really glad you mentioned the start-stop cycles thing, that's super helpful to know beforehand. I'll make sure to pass this info to my mechanic about checking the whole wiring harness too. The corrosion tip is especially useful since I'd rather fix everything while they're already working on it. I've actually just booked it in for tomorrow morning. After hearing about your experience with the same error code and similar symptoms, I'm feeling much more confident it's just the wiring connection and not something more serious. I'll probably end up asking them to do that preventive maintenance you mentioned too, seems worth it to avoid any future issues. Thanks again for all the help!