BMW Z3 Electric Fan Failure Causing Critical Engine Heat

Hey there! I had a similar issue with my 2003 BMW M3 last summer. The overheating symptoms matched yours exactly, emergency mode and all. Turned out the cooling fan wasn't engaging because of a faulty connection at the control module. Initially thought it was the fan itself, but my mechanic found corroded wiring between the fan control module and the ECU. They had to replace the wiring harness and clean the connector pins. Not a complex repair, but definitely needed professional diagnostic tools to pinpoint the exact issue. It's not something you want to ignore though, mine started intermittently at first but got worse quickly. If left unchecked, it could lead to serious engine damage. The repair took about 4 hours including diagnostics. Been running perfectly since then, no more emergency mode or overheating issues. Worth getting it checked out by a BMW specialist rather than a general mechanic, they'll know exactly where to look for these model-specific issues.

Thanks so much for sharing your experience! Really helpful to hear from someone who went through the same thing. Since you had it fixed, I was wondering, do you remember roughly how much the repair set you back? And has everything stayed running smoothly with the cooling system since then, or have you noticed any other quirks pop up? I'm trying to get a sense of what I might be looking at cost-wise and whether this fix tends to last. My Z3's symptoms sound identical to what you described.

Hey again! Just wanted to follow up, I actually got this fixed last week and I'm happy to share how it went. Just like in my case with the M3, it turned out to be exactly what I suspected, a faulty connection was causing the electric fan issues. The mechanic found and repaired the problematic cable connection and it cost me 95€, which honestly wasn't as bad as I feared. The car's running like a dream now, no more emergency mode or overheating problems. The fix was pretty straightforward once they identified the exact issue. I've put quite a few miles on it since the repair and everything's stayed perfect with the cooling system. Really glad I didn't put it off any longer. When these electrical connections go bad, they can definitely cause bigger headaches if left unchecked. If your symptoms are matching what mine were, you're probably looking at a similar fix. At least now you have a rough idea of the potential cost. Hope this helps with your decision!

Thanks for all the details about your repair! You've actually convinced me to bite the bullet and get it checked out. I took my Z3 to a specialist mechanic yesterday, and you were spot on about the wiring issue. The problem was a bit different though, turned out I had a cracked coolant reservoir that was causing the overheating, plus some worn-out wiring that needed replacing. The whole thing was pricier than yours, came to about double what you paid, but the mechanic did a thorough job. They even spotted and fixed a few minor issues I hadn't noticed. Been driving it since yesterday, and what a difference! No more emergency mode warnings, and the temperature gauge stays exactly where it should. Really appreciate you sharing your experience, it gave me the push I needed to get it sorted before it turned into something worse. Looks like we both dodged some potentially serious engine damage by getting it fixed when we did!