BMW Hybrid Cooling Leak Causing Emergency Shutdowns

I had a similar issue with my 2014 BMW 5 Series Hybrid. Started with the same symptoms, overheating, emergency mode, and warning lights. Initially thought it was just low coolant, but turned out the wiring harness connecting to the cooling system control module was damaged. Got it checked at my regular garage last month. The mechanic found that some connections were corroded and a few wires were practically bare. This was causing the control unit to receive incorrect temperature readings, leading to the overheating warnings. They had to replace the entire wiring harness and reset the control module. It wasn't a quick fix, but honestly better than replacing the whole cooling system. The car's been running perfectly since then, no warning lights or emergency mode triggers. If your symptoms match, have them check the wiring and connections first before jumping to major cooling system repairs. The issue was serious enough that continuing to drive could have caused actual engine damage, even though the initial problem was just electrical. Worth getting it sorted soon.

Hey, thanks for sharing your experience! Really helpful to hear from someone who's dealt with similar issues. Sounds like my problem could be related to what you had with the wiring harness. I'd be curious to know how much you ended up paying for the repair? Also, has everything been running smoothly since the fix, or have you noticed any other quirks popping up?

Hey there! Happy to give you an update. After getting it fixed at the mechanic's, I paid 95 € for the repair, turned out it was just a faulty cable connection to the component that needed fixing. Much cheaper than I initially feared! And yes, everything's been running perfectly smooth since then. The control unit communication error that was causing all those scary warning lights and overheating issues is completely gone. No more emergency mode, no more warning lights, and the engine temperature's staying exactly where it should be. I was honestly relieved it wasn't anything more serious like a full cooling system replacement. Sometimes these electrical gremlins can make the problem seem way worse than it actually is. Haven't noticed any other issues at all since the repair, my BMW's back to running like a dream. Definitely sounds like you're dealing with something similar to what I had. Best to get it checked out soon, but hopefully it'll be a simple fix for you too!

Thanks for the follow-up! Actually, I just got back from a new mechanic who took a proper look at my car. You were right, it wasn't as terrible as I first thought. The mechanic found some damaged wiring near the coolant sensor, plus a small crack in one of the connecting hoses. Got it all fixed yesterday and it cost me a bit more than yours, around 300 due to the hose replacement, but still way better than what I was imagining. The car's running great now, no more warning lights or emergency mode drama. Temperature gauge is staying steady too. Really glad I asked here before going for a complete cooling system overhaul. Sometimes these problems seem huge but end up being fairly straightforward fixes. Definitely learned my lesson about getting a second opinion when the first mechanic seems unsure. Thanks again for pointing me in the right direction!