Here is tutorial on how to check and monitor bmw coolant water temperature on board screen.
Bmw water temperature sensor.
Make sure to clean the sensor s insert area before you reinstall the temperature sensor.
But it will also work o.
Clean the hole where the sensor is located.
Repair and replacement of the temperature sensor.
How to change the temperature sensor on a bmw k75 100.
Remove the coolant temperature sensor.
Explains and demonstrates how to replace the outside temperature sensor.
The sensor controls the fan but more importantly it controls the ecu for the fuel injection.
This includes replacemet of the pi.
Using a drive socket and extension and the correct sized socket usually 19mm loosen the sensor from the engine block and remove it entirely.