BMW X1 Overheating Crisis: Coolant Leak Nightmare

Hey there! I had a really similar issue with my 2017 BMW X3 last year (I have some experience working on cars but nothing too advanced). Those symptoms sound exactly like what I dealt with, the overheating, emergency mode, and warning lights were giving me anxiety! Turned out it was a faulty wiring connection to the coolant control module. My trusted mechanic found that one of the connector plugs was corroded and not making proper contact. The repair was pretty straightforward, they replaced the wiring harness and connector, which cost me around 95 Euro, and that sorted everything out. Could you tell me if you've noticed any other symptoms, like rough idling or changes in engine performance? Also, which engine variant does your X1 have? This info would help me confirm if it's the same issue I experienced. P.S. I know BMW also had similar issues with the X2 from that generation, so it's a known weak point in some models.

Thanks for the detailed reply! Yeah, now that you mention it, I've noticed some rough idling, especially when the engine's warm. My X1 has been running perfectly until this started happening at 11117 KM. Had my last service just two months ago and everything was fine then. I'll definitely have my mechanic check the wiring connections to the coolant module. That's actually really helpful to know about the connector corrosion issue, makes total sense given the symptoms. Did you notice any particular signs before the problem got really bad? Just wondering if I should watch out for anything specific while getting this sorted.

Hey again! Glad I could help with my previous experience. Yeah, looking back now, I definitely noticed some warning signs before it got serious with my X3. About 2-3 weeks before the full breakdown, I started getting occasional temperature fluctuations on the gauge, but they were so brief I brushed them off, big mistake! The rough idling you mentioned is exactly what I experienced too. Mine started doing it particularly when stopping at lights. I also remember the coolant level dropping faster than usual, but I kept topping it up thinking it was normal in hot weather (another mistake!). Since you've got low mileage like I did when it happened (mine was around 12000 KM), and especially since you've had a recent service, I'm even more convinced it's the same wiring issue. When my mechanic fixed it, he showed me how the connector had gotten corroded despite the low mileage, apparently, it's just a design weakness in these models. Quick tip from my experience: while you're getting it checked, have them look at the coolant temperature sensor too. Mine was starting to act up as well, though it wasn't the main problem. Better safe than sorry with these things. Keep me posted on what you find out. I'm really curious if it turns out to be the same issue!

Thanks so much for all these details! It's actually a huge relief to hear about those early warning signs you experienced, the temperature gauge fluctuations and faster coolant consumption match exactly what I've been seeing. I was definitely making the same mistake of ignoring those initial signs! Really appreciate the tip about checking the coolant temperature sensor too. I've already called my mechanic and managed to get an appointment for tomorrow morning. I mentioned the wiring harness issue and connector corrosion you experienced, and he seemed to think it's a strong possibility given the symptoms. This has been super helpful, definitely saved me from spending ages trying to diagnose the problem. I'll update you once the mechanic has taken a look. Fingers crossed it's as straightforward as your repair was!