BMW 1 Series Overheating: Dead Fan Leading to Trouble?

Hey there! I had something similar with my 2009 BMW 3 series (320i). I've got some experience working on cars, but cooling issues can be tricky. Initially thought it was just the fan too, but my mechanic diagnosed a faulty speed sensor that was causing the radiator fan to malfunction. Got it fixed at my local workshop and it cost me around 250 Euro. Since then, no more overheating issues. Before you head to the shop, what's your exact engine type and mileage? Also, have you noticed any coolant leaks or unusual noises? These details would help me share more specific advice based on my experience with BMWs. Don't want to alarm you, but I'd avoid driving it until it's checked out, overheating can cause serious engine damage.

Thanks for the info! Just to add, I'm at 110524 KM and had my last service about 3 months ago. I haven't noticed any coolant leaks, but there's definitely a slight humming noise when the engine's running. Appreciate the heads up about not driving it, I've parked it for now. Those BMW speed sensors can be tricky, so that's really helpful to know. Did your mechanic mention any other common causes they typically check for with these symptoms?

Hey again! Thanks for the additional details about your 1 series. Yes, actually, when I had my 320i fixed, my mechanic did mention several other potential causes they usually check with these symptoms. In my case, while the speed sensor was the culprit, they also checked the coolant temperature sensor, thermostat, and the fan relay. These are apparently common failure points in our BMWs. The humming noise you mentioned, I had that too! In my case, it was related to the failing speed sensor, but they told me it could also indicate a failing water pump. My mechanic actually showed me that these BMWs have an electric fan system that's controlled by the ECU (Engine Control Unit), so when the speed sensor goes bad, it can't properly tell the fan when to kick in. That's why you get both the overheating and the check engine light. Since your mileage is pretty similar to what mine was when I had the issue (I was at around 115000 KM), it might be worth having them check all these components. The good news is that once they found and fixed the actual problem, it's been running perfectly for the past year. Just make sure they do a proper diagnostic before replacing parts, learned that lesson the hard way when I first tried fixing it myself!

Thanks everyone for your help! After all this great feedback, I'm definitely getting a clearer picture of what might be wrong with my BMW. That's really interesting about your experience with the speed sensor, seems like these cooling system issues are pretty common in our BMWs. It's actually a relief to hear that fixing your speed sensor solved the problem completely. I've called my mechanic and booked it in for tomorrow morning. Told them about the speed sensor possibility, and they're going to check the water pump, thermostat, and fan relay too. The humming noise thing being related to the speed sensor makes total sense now, hope it's the same in my case! Really glad I asked here before trying to fix it myself. Could've ended up making things worse! I'll update everyone once I get the diagnosis. Thanks again for saving me from potentially damaging my engine, definitely keeping it parked until tomorrow's appointment.