[danielbmw]

can a bad coolant temperature sensor cause the radiator fan to run at full blast on start up?

2013 335i N55

water pump was recently changed but i didn’t change the thermostat because it was working just fine.

[e91Owner]

Originally Posted by danielbmw

can a bad coolant temperature sensor cause the radiator fan to run at full blast on start up?

2013 335i N55

water pump was recently changed but i didn’t change the thermostat because it was working just fine.

This can be caused by a lot of things and guessing based on your description is somewhat of a fool’s errand. If you can posts the codes you are experiencing, it will help. If you’re not getting any DTCs, it’s possible your refrigerant is over-charged, but that wouldn’t just happen out of the blue. I would only suspect that if it had been serviced recently.

[eljay]

Originally Posted by danielbmw

can a bad coolant temperature sensor cause the radiator fan to run at full blast on start up?

2013 335i N55

water pump was recently changed but i didn’t change the thermostat because it was working just fine.

Yes, it can,but it can be another thing in the cooling system.
Basically, if cooling management fails (sensor, thermostat etc.), the car wants to protect itself from overheating and fans come on immediately.

[augustus maximus]

Originally Posted by danielbmw

water pump was recently changed but i didn’t change the thermostat because it was working just fine.

That was a mistake.