BMW 6 Diesel Overheating + Coolant Leak: What's Wrong?

Hey there! Had a similar issue with my '04 BMW 5 diesel (had around 95k km then). From my experience at the garage last month, this sounds exactly like what I dealt with. The symptoms matched, engine overheating, limp mode, warning lights, and coolant leak. Turned out the electric water pump's wiring harness was damaged, causing communication errors with the control unit. The coolant leak was actually coming from a cracked connection where the cable routing had worn through over time. It wasn't just a simple fix, the mechanics had to replace the entire wiring harness and connectors to the water pump. They also found some corrosion in the connector pins that needed cleaning. While they were at it, they replaced the water pump as a precaution since everything was already apart. Not trying to scare you, but this isn't something you want to ignore, the engine can get seriously damaged if it keeps overheating. My advice would be to get it checked at a BMW specialist rather than a general mechanic. Hope this helps with your decision making!

Thanks for sharing your experience! that sounds exactly like what I'm dealing with. The wiring harness issue makes total sense with these symptoms. How much did you end up paying for all that work? Also, just curious, has everything been running smooth since the repair or have you noticed any other issues pop up?

Hey again! Just wanted to let you know that after getting my car fixed, everything's been running perfectly fine, no more issues at all! The control unit communication error they found was exactly what was causing the trouble, and fixing that sorted everything out. The repair was actually way cheaper than I expected, only 95 € to fix the faulty cable connection. Way better than what I initially paid for all that work I mentioned before! Honestly, I was relieved it wasn't something more serious like when they had to replace my entire wiring harness. The car's been running like a dream since then, no more overheating, no warning lights, and definitely no more coolant leaks. It's amazing how something as simple as a bad connection can cause so many scary symptoms! I'd definitely recommend getting yours checked out asap, might save you from a bigger repair bill down the road. Let me know how it goes with yours. Always happy to share more about my experience if you need it!

Thanks for the follow-up! Just got back from a different mechanic and wanted to share what happened. You were right about getting it checked quickly. Turned out my issue was a bit different though. The coolant leak was coming from a cracked thermostat housing, and they found some loose connections in the wiring that were causing those error messages. Cost me around 200 for parts and labor, which wasn't as bad as I feared. Got it back yesterday and the engine's running cool again, no warning lights, and best of all, no more leaks! Really glad I didn't wait any longer to get it fixed. This new mechanic was actually great, took the time to show me exactly what was wrong and explained everything clearly. Think I've finally found a reliable place for future repairs. Thanks again for your help and sharing your experience, it really helped me understand what I was dealing with!