BMW Z4 Electric Fan Failure Causing Engine Overheating

Had the same issue on my 2017 BMW M240i last summer. The overheating and emergency mode turned out to be more than just the fan, it was a faulty wiring harness connector to the cooling system control module. Initially thought it was the fan too, but my mechanic found corroded pins in the main connector that controls both the fan and temp sensors. The connection would fail intermittently, especially during hot weather or long drives. Had to get the entire harness assembly replaced as the corrosion had spread. It's definitely a serious issue that needs immediate attention since continuous overheating can damage your engine. The repair involved removing several components to access and replace the wiring harness. Cars in this series seem prone to this issue after about 100,000 km. Don't wait on this one, get it checked by a certified BMW specialist. My car runs perfectly now with no overheating issues since the repair.

Thanks so much for sharing your experience with the wiring harness issue. Super helpful to know it wasn't just the fan! My Z4's showing the exact same symptoms you described, especially acting up after longer drives. I'll definitely get a BMW specialist to check the connectors and wiring. Can't help but wonder, do you remember roughly how much you ended up paying for the whole repair? Also, has everything been running smoothly since then, or have you noticed any other cooling-related quirks?

Hey again! Just wanted to update you since my last post about my M240i's cooling issues. I actually just got my car back from the shop last week. Turns out I was lucky, it wasn't the whole wiring harness after all. The mechanic found it was just a faulty cable connection to the electric fan component. Much simpler fix than what I initially had done on my car last summer! Total bill came to 95 €, way less than I expected after my previous experience. The car's running like a dream now. No more overheating warnings or emergency mode triggers, even on longer drives. Honestly, what a relief! Sometimes the simpler fix is all you need. If your symptoms are similar to what mine were, might be worth having them check the fan connections first before diving into bigger repairs. Let me know how it goes with your Z4. Always happy to share experiences with fellow BMW owners.

Just got back from the mechanic and thought I'd update everyone. What a relief, it turned out to be a quick fix! Took your advice and went to a certified BMW specialist. They found the same issue, just a bad connection to the electric fan. Spent about two hours in the shop while they cleaned the connections and replaced a couple of worn wires. Cost me less than I expected, and now my Z4's running perfectly. The mechanic also did a quick check of the entire cooling system while they were at it. Everything else looked good, which was reassuring. No more emergency mode warnings or overheating problems since then, even on my longer commutes. Thanks again for pointing me in the right direction! Really saved me from potentially spending way more on unnecessary repairs. Sometimes the simplest solution really is the best one.