BMW i3 Coolant Warning: Fix Before Major Engine Damage

I had a similar issue with my 2018 BMW i8 Hybrid last month. The coolant warning light and check engine popped up around 115,000 km. After checking at the garage, it turned out the coolant temperature sensor connection was loose and had some corrosion. The wire harness needed cleaning and the connector needed replacement. The mechanic said it could've been serious if ignored, potentially leading to overheating and engine damage. While checking that, they also found the coolant level was slightly low due to a minor leak at one of the hose clamps. Not sure if your issue is identical, but with these symptoms on a BMW hybrid, it's usually either the sensor connection or a leak in the cooling system. Better to get it checked soon to avoid any major problems. My repair wasn't too complicated, took about half a day at the garage.

Hey, thanks for sharing your experience! That sounds exactly like what I'm dealing with right now. My mechanic actually fixed it last week, and it was indeed a sensor issue plus a small leak. Really glad I didn't ignore it. By the way, do you remember roughly how much you ended up paying for the repair? Also, has everything been running smoothly since then? Just wondering if any other issues popped up afterward. I've heard these sensor problems can sometimes be a sign of other stuff going wrong.

Hey again! Glad to hear you got it sorted, sensor issues can be really annoying! For my repair, I paid 95 € to fix the cable connection problem. Pretty reasonable considering what could've happened if left unchecked. And yep, they topped up the low coolant level while they were at it. Since the repair, my i8's been running like a dream, no warning lights, no temperature issues, nothing. It's been about six weeks now, and everything's still perfect. I was worried like you about other potential problems, but honestly, it seems it was just an isolated issue with that sensor connection. These hybrids are pretty solid once you sort out the little niggles. Just keep an eye on your coolant level for the next few weeks, I check mine every couple of weeks now just to be on the safe side. But I doubt you'll have any more trouble since they've fixed both the sensor and the leak. Sounds like you caught it at the right time, just like I did!

Thanks for the follow-up! You're right about catching it early, that was definitely key. I ended up paying a bit more than you, around 150 for parts and labor, but totally worth it for peace of mind. Let me tell you about my mechanic visit though, it was actually a way better experience than my last one. This guy really knew his stuff about hybrids. I drove in pretty nervous after that horrible experience at my previous mechanic, but this new place was different. They diagnosed it quickly, explained everything clearly, and had me back on the road the same day. The mechanic even showed me exactly where the sensor was failing and how the small leak had developed. Now my car's running perfectly, no more warning lights or temperature issues. Really appreciate your help on this. Think I've found my new go-to mechanic too, which is a huge relief. Just checked the coolant level yesterday actually, and everything's still spot on. Lesson learned though, won't ignore those warning lights again!