Ok, my wife has a 2008 mini Cooper S (turbo) model. I have replaced the temperature sensor housing unit three times now. The check engine light is still on. In this third time around, after bleeding out the air etc, it still acts as if it's overheating. The following morning I walked with my wife to her car and she didn't even crank it up and the damned fans came on by itself!
WTH? If I'd known that these cars are such a pain in the rear, I'd have talked her into getting a different car! What is going on here? Anyone else ever had this issue? This is beyond ridiculous! Thanks in advance for any help I can get.

 

I had this issue on my girlfriends R55 Clubman S after doing the thermostat. Turned out to be a bad Coolant temp sensor for me. If the fan is coming on when the car is cold it sounds like the Coolant temp sensor. The fan will also come on if you unplug the sensor. Have you scanned the car to see what the code is?

 

^^^^ Chances are that the coolant temp sensor has failed and is giving a false reading.

We have plenty of thermostats in stock if you end up needing one!

N14 Thermostat