Hello NAM members, new member here looking for help. My wife purchased a 2008 S this spring and the other morning she started it and the fan came on high and within a minute the over heat warning came on. Bled for air off the thermo, coolant up no air. Here is the kicker, we live in fairbanks alaska and there are no mini dealers or bmw here, maybe a bad move on our part! I am fairly mechanically inclined and it looks like i will have all winter too figure it out. Electircal? temp senser, ECU. feel'n like parts and process of elimination for me, once i figure out where everything's at. Any help would be deeply appreciated. THANKS!

 

My water pump had to be replaced after my car did the same thing, also an 08 s. It had overheated before but they never got around to telling me why, they just rebuilt part of the engine and pretty much refused to give me an explanation

 

If your engine temperature warning lamp comes on when it's cold, I'd consider replacing your coolant temperature sensor. It is only $22 and it takes aboit 5 minutes to replace. I was getting an overheating warning, the moment I started my car. Fan would come on and drain the battery. When it didn't drain the battery, it would
be nearly impossible to start the next morning. Once I replaced my coolant temperature sensor, it was back to normal. Easy starts, improved fuel mileage, and no blasted erroneous light!!!

 

The sensor just slips in and is held in place with a clip. It's located right next to the bleed screw on the thermostat housing. Just had to pull the air duct from the air filter to the turbo. 2 clamps, a pull clip, and two screws, on the breather unit.

The goofiest thing about my whole problem was that when the car warmed up, the "overheating" issue went away. Obviously, my car was never overheating, it was just the sensor malfunctioning