BMW 4 Diesel Overheating & Limp Mode: Fan Failure Help

Had the same issue with my 2020 BMW 3 Series diesel last month. Initially thought it was the electric fan too, but turned out the problem was more basic. The technician found a damaged wiring harness connecting to the coolant temperature sensor, some cables were corroded and making poor contact. The sensor wasn't getting proper readings to the ECU, causing the engine management system to think it was overheating and triggering limp mode. It wasn't a major repair, but definitely needed immediate attention to prevent any actual overheating damage. If you're looking for peace of mind, I'd suggest going to a certified BMW specialist. They have the right diagnostic tools to pinpoint the exact issue. Better not to risk it with general mechanics on these modern engines. In my case, they also found and fixed a minor coolant leak while they were at it, which could've caused real overheating problems down the line. The whole thing took about half a day to sort out.

Thanks for sharing your experience! That's quite interesting about the wiring harness, really helpful to know. It's good you caught that coolant leak too before it turned into something worse. How much did the whole repair end up costing you, if you don't mind me asking? Also, have you had any other cooling-related issues pop up since the repair was done? I'm trying to get an idea of what I might be looking at here with my car.

Hey there! Happy to give you the update. After getting the car fixed, I haven't had a single cooling issue, it's running perfectly now. The mechanic found exactly what I suspected: the electric fan wasn't working because of a faulty cable connection. Pretty straightforward fix, actually. The total bill came to 95 € which was mainly for fixing that cable connection. Much cheaper than I initially feared! The mechanic also did a thorough check of the entire cooling system while they were at it, just to be safe. Everything else was in good shape. I've put about 3,000 km on the car since the repair, and the temperature gauge has stayed exactly where it should be, no more overheating warnings or limp mode. It's such a relief when these things turn out to be simpler than you expect. The BMW is running like new again. Honestly, it sounds like your symptoms are pretty similar to what I experienced, so hopefully it's something equally straightforward for you too.

Thanks so much for the detailed follow-up! I actually went ahead and got my car checked out after reading your earlier response. You were right about it being a relatively simple fix, turned out my radiator fan motor was failing. The mechanic I found was really thorough and showed me exactly what was wrong. Cost me a bit more than yours at around 300 for parts and labor, but totally worth it for peace of mind. They had it done in about three hours. Best part is, the car's running perfectly now. No more overheating warnings or limp mode issues. I've driven it hard for the past few days just to be sure, and the temperature stays rock steady. Guess I was lucky to catch it before any serious damage happened! Really appreciate everyone's input on this. It definitely helped me make a more informed decision about getting it fixed. Sometimes these car problems seem scary at first, but they often turn out to be quite manageable.