BMW M2 Overheating + No Heat = Failed Bypass Valve?

I had very similar issues with my 2014 BMW M4 last year. When my engine started overheating and the heater stopped working, it turned out my water pump had failed, which then caused damage to the thermostat housing. The check engine light came on because the car's computer detected irregular coolant temperature readings. Had to get both the water pump and thermostat replaced, plus a full coolant system flush. It was quite serious since continued driving could've led to engine damage. The technician explained that these parts tend to fail on these engines around the 130-150k km mark. I'd suggest getting it checked soon, those symptoms together usually point to coolant system issues rather than just a bypass valve. Make sure whoever works on it is familiar with BMW M series engines, as they have some specific cooling requirements.

Thanks for sharing your experience with the M4! That's really helpful. My symptoms do sound pretty similar to what you went through. Had the car diagnosed yesterday and you're spot on, looks like I'm dealing with a failing water pump. Quick question, do you remember roughly how much you ended up paying for the full repair? Also, has everything been running smoothly since the fix? I want to make sure I budget properly and know what to expect. Thanks again for the advice about getting it checked by someone who knows M cars. Definitely don't want to risk any engine damage!

Hey again! Glad I could help with the diagnosis! Just want to let you know that after I had my M4 fixed, everything's been running like a dream. The overheating issues and heater problems completely disappeared. Actually, turns out in my case the bypass valve malfunction was just a consequential error from the water pump issue, which they fixed without any extra charge. That was a nice surprise! For the total cost, the water pump replacement, thermostat housing, and coolant flush came to around 1200 € at my BMW specialist. Could vary a bit depending on part prices these days though. But honestly, it was worth every cent to get it done right and prevent any serious engine damage. It's been about 15 months since the repair now, and I haven't had a single cooling-related issue. The engine temperature stays perfectly stable, and the heater works great. Just make sure you get a proper BMW specialist to do the work, it really makes a difference with these M engines. Let me know how it goes with your repair!

Thanks so much for all the detailed info! Just got back from the mechanic today actually. You were absolutely right about everything, the water pump was the main culprit. Found a really good BMW specialist who knew exactly what they were doing. Total cost ended up being pretty close to what you mentioned. They also caught a small coolant leak while they were at it, so got that sorted too. The whole thing took about a day and a half, but the car's running perfectly now. Temperature gauge is steady, heater's working great, and that annoying check engine light is finally off! Really appreciate you taking the time to share your experience. Definitely saved me from stressing too much about it. Will keep an eye on things, but feeling pretty confident about the fix. Thanks again for all your help!