BMW X7 Coolant Leak Nightmare: Emergency Mode Issues

Hey there! I've had some experience working on cars, nothing too extensive but I know my way around basic repairs. I actually faced something similar with my 2017 BMW X5 about eight months ago. The symptoms were pretty much identical, overheating, emergency mode, and those annoying warning lights. Turned out the coolant level sensor had a faulty connection, which was causing all sorts of confusion in the system. Took it to my regular workshop, and they diagnosed a damaged wiring harness that connects to the coolant sensor. The cable had worn out and was causing intermittent connection issues. Fixed me up with a new harness and properly sealed connections, cost me 95 Euro and haven't had any problems since. Can you share your vehicle's mileage and whether you've had any recent repairs done to the cooling system? Also, when you notice the coolant leak, is it more prominent after the car has been running for a while or is it constant? This info would help figure out if you're dealing with the same issue.

Thanks for sharing your experience! My X7 has 115664 KM on the clock, and the last service was just regular maintenance about 2 months ago. The coolant leak seems to be worse after the car's been running for about 20 minutes, especially when the engine's hot. I'll definitely get that wiring harness checked out since your symptoms match mine pretty closely. It's giving me some hope that this might not be as serious as I initially thought. Did you notice any specific signs before your sensor completely failed? Just trying to understand if I should look out for anything particular when I take it to the workshop.

Hey again! Thanks for the follow-up. After reading about your leak pattern, I'm actually thinking it might be different from what I experienced. With my X5, even when the wiring harness was acting up, I never had actual coolant leaks, it was more about false readings. Given that you're seeing real coolant loss when the engine's hot, I'd bet you're dealing with a failing water pump or a cracked expansion tank. These are pretty common issues in our BMWs. I actually had my expansion tank replaced about two years before the wiring problem happened. The timing of your leak (20 minutes into running) is really telling. That's typically when the system hits full pressure and temperature. In my case, before the wiring issue, I didn't notice any warning signs except for occasional temperature gauge fluctuations. But your situation sounds more mechanical than electrical. Have you noticed any sweet-smelling coolant vapor when the engine's running? With my previous expansion tank issue, that was a major tip-off. Might be worth checking, just don't get too close to the hot engine while doing it. I learned that lesson the hard way! I'd suggest getting it checked soon though. These cooling issues can escalate pretty quickly in our BMWs. Trust me, it's not something you want to put off!

Thanks for the detailed insight! You've actually got me worried now about the water pump or expansion tank, that makes a lot more sense given the actual coolant loss. And yes, now that you mention it, I have noticed that sweet smell, especially when parked after a drive. I just didn't connect the dots earlier. You're absolutely right about not putting it off. I've already called my mechanic and booked it in for tomorrow morning. Better safe than sorry, especially with these complex cooling systems. Really appreciate you taking the time to share both your experiences, the wiring issue and the expansion tank problem. It's given me a much clearer picture of what to discuss with the mechanic. I'll definitely avoid getting too close to the hot engine, thanks for that warning! Will update the forum once I know what's actually causing the problem. Thanks again for all your help!

Where have my questions gone, I wanted to see if I have already received an answer, I can't remember the exact question I asked. Only that terminal 30g-f switches off from time to time and I have to reset the time. I would also like to know where I can find the oil pressure switch and the oil temperature sensor on my bmw 3 series e90 n47d20a 🤔 I think the oil pressure switch is located right under the oil filter. But I can't find the oil temperature sensor. And when changing the replacement water pump, do I have to bleed the coolant again after feeling it? Can you help me there thanks LG.

(Translated from German)

Hello Mani39, For your BMW E90 N47D20A, the oil pressure switch is indeed below the oil filter housing, while the oil temperature sensor is likely near the oil pan or filter housing. When replacing the water pump, you must bleed the coolant system to prevent air pockets that can cause overheating. If you have trouble, consulting a professional mechanic might be helpful. Let me know if this resolves the problem or if you need further assistance.