If the sensor is open [ check w/ohm meter] , the fans will run all the time..regardless of temp..
Same is true if it is unplugged.
When either of these condition arise, the computer defaults to ON fan mode....
I have a sensor ohm/temp reference chart, if needed...
The resistance goes down as the temp goes up... this is called NTC thermistor [ Neg temp] , so an ohms reading at gauge temp
camparison to chart will tell if the sensor is OK and in calibration...