BMW Z4 Radiator Fan Fails, Engine Overheating Signs

Had similar issues with my 2014 BMW M235i last summer. The symptoms you're describing match exactly what I experienced, overheating engine and inactive cooling fan with CEL on. Initially thought it was just the fan, but my mechanic found it was actually a failed speed sensor that wasn't triggering the fan operation. The sensor was totally shot, and because it wasn't sending proper signals, the fan wasn't activating when needed. The repair wasn't terribly complicated, but it was crucial to fix quickly to prevent potential engine damage from overheating. They had to replace both the speed sensor and clean out some corrosion in the connector. The cooling system got a full inspection while they were at it. After the fix, everything went back to normal. No overheating issues since then, and the fan kicks in exactly when it should. I'd suggest getting it checked soon, running hot isn't something you want to ignore on these engines.

Hey, thanks for sharing your experience. That's really helpful since it sounds exactly like what I'm dealing with. Good to know it might be the speed sensor rather than the entire fan assembly. Just curious, do you remember roughly how much the repair set you back? Also, has everything stayed working properly since the fix? I'm trying to budget for this and want to make sure I fix it right the first time.

Hey there! Yeah, happy to help clear things up. Just got back from my mechanic last week actually, the total bill came to 250 € for fixing that pesky speed sensor. Pretty reasonable considering what could've gone wrong if left unfixed. And I'm stoked to report everything's running like a charm now! That radiator fan is working exactly as it should, kicks in right when needed and keeps the engine temp perfectly regulated. Such a relief after dealing with those overheating issues. The M235i's been performing beautifully since the repair, no problems whatsoever. Trust me, getting it sorted properly the first time is definitely worth it. You'll save yourself a lot of stress and potentially bigger problems down the road. My mechanic did a thorough job checking everything while they were in there, which gave me good peace of mind. Best money I've spent on the car in a while!

Thanks a lot for the detailed info! I actually bit the bullet and got it fixed yesterday. Turns out you were spot on, it was the speed sensor causing all the trouble. Found a really good mechanic through a car enthusiast. The repair was pretty straightforward and cost me about 300 with parts and labor. They did a full cooling system check while they were at it, which was reassuring. The fan's now kicking in perfectly and the engine temp's staying right where it should be. Funny thing is, they showed me the old sensor and it was completely corroded. Can't believe such a small part caused so much worry! Really glad I didn't put this off any longer. The car's running great now, and I actually trust this new mechanic, they explained everything clearly and didn't try to upsell me on unnecessary work. Sometimes good things come from bad situations, right?