BMW M6 Warning Lights: Coolant Issue or Engine Trouble?

Hi there! I have some experience working on BMWs. Actually, I had a similar issue with my 2017 BMW 4 Series last year. Those warning lights can definitely be nerve-wracking! In my case, it turned out to be a faulty wiring connection to the coolant temperature sensor. The workshop found that the connector was corroded and not making proper contact. They replaced the wiring harness and connector, which cost me around 95 Euro. Problem solved after that! What's your exact model (630i, 640i) and how many miles do you have on it? Also, have you noticed any coolant leaks or had to top up the coolant recently? This info would help me understand if you're dealing with the same issue I had. If you're getting an error code, I'd recommend getting it scanned first before assuming it's just low coolant. Sometimes these symptoms can be misleading.

Thanks for your reply! I've got a 640i with 16227 KM on the clock, and just had its service last month. Haven't noticed any coolant leaks on the ground, but I'll definitely get that error code scanned as you suggested. Really appreciate your detailed explanation about the wiring harness issue, gives me a good starting point to investigate. Just trying to gather as much info as possible before heading to the workshop.

Hey again! Thanks for coming back with those details about your 640i. You know, hearing about your recent service actually reminds me of something I forgot to mention about my experience. When I had that wiring harness issue on my 4 Series, it also happened pretty soon after a service, probably about 6 weeks later. The interesting thing is that the mechanic told me sometimes when they're doing other work in that area during service, the wiring can get slightly disturbed without anyone noticing. Since you haven't noticed any leaks and you've just had it serviced, I'm even more convinced it might be similar to what I experienced. The symptoms are just too similar, same warning lights and everything. Mine was showing around 15000 KM when it happened, so pretty close to your mileage too. Just a heads up though, when you get it checked, make sure they look at the whole cooling system while they're at it. Even though my main issue was the wiring, they found that my coolant temperature sensor was starting to go bad too. Might be worth checking in your case as well. Let me know what you find out when you get it looked at. Always curious to hear if these issues are becoming a pattern in these models!

Thanks so much for sharing those extra details! It's really helpful to know your issue happened right after servicing too, that's such a interesting connection. I'm actually feeling a bit more optimistic now since your symptoms match mine so closely, and we're even in the same mileage range. I've already called my regular mechanic and booked it in for tomorrow morning. I'll definitely ask them to check both the wiring and the coolant temperature sensor like you suggested. Really appreciate you taking the time to share your experience in such detail. I'll try to remember to post an update once I get the diagnosis, might help other BMW owners down the line if they run into similar issues. Thanks again for all your help!