BMW 1 Series Temp Gauge Issues: Cold Engine Mystery

Hey there! I had similar issues with my 2019 BMW 3 Series 320d. Last month, my car showed the same symptoms, slow warm-up, temp gauge fluctuating, and check engine light. Took it to the garage and the diagnostic revealed a faulty thermostat and a blown fuse in the cooling system's control module. The thermostat wasn't opening properly, which explained the warming-up issues. The cooling grille wasn't even part of the problem. It was a relatively serious issue because running the engine too cold for extended periods can cause carbon buildup and affect fuel efficiency. Not something you want to ignore. The fix wasn't too complicated, replaced the thermostat, control module fuse, and did a system reset. Back to normal now, temp gauge's steady and warm-up time is back to about 5-7 minutes. Best to get it checked soon. These symptoms shouldn't be ignored, especially in a diesel engine.

Hey, thanks for sharing your experience! That's really helpful since I've been worried about my car too. Same exact symptoms you had, the temp gauge going crazy and slow warm-up times. Definitely sounds like we had the same issue. Would you mind telling me how much the repair set you back? Also, has everything been running smoothly since the fix, or have you noticed any other problems pop up?

Hey again! Happy to update you! My fix was actually different from what we initially thought. When I took it to the mechanic, it turned out the main issue was just the cooling grille being restricted, much simpler than my first guess about the thermostat. They also found and replaced a blown fuse which cost 52€. Everything's been running perfectly since then, temp gauge is stable, car warms up normally now, and no more check engine light. Such a relief! It's been about three weeks since the repair and honestly, the car feels like new again. The engine's running smoother and the warm-up time is back to normal. I was really lucky it wasn't the thermostat after all, as that would've been a much bigger job. Sometimes the simplest fixes make the biggest difference! Just goes to show it's worth getting things checked out properly rather than making assumptions. Hope this helps with your decision! Let us know how you get on with yours.

Thanks everyone for the advice! Just wanted to update you on what happened with my car. I bit the bullet and took it to a new mechanic yesterday. Turns out it wasn't the cooling grille after all, they found a cracked thermostat housing and a couple of loose connections in the cooling system. The mechanic showed me everything and explained it really well, which was a nice change from my last experience. The repair took about three hours, and while it wasn't cheap, at least I know what I paid for. Best part is, the car's running like a dream now. The temperature gauge is steady, it warms up normally, and that annoying check engine light is finally off. Really glad I didn't try to diagnose it myself or delay getting it fixed. These things can get worse pretty quickly. Thanks again for sharing your experiences, helped me make the right call!