Right under the thermostat its had to see because exhaust crossover needs to move to loosen it up. You can also remove the upper motor mount bracket to access the sensor using a wrench to remove sensor.
It is the coolant temp sensor near the upper radiator hose.
Check the temperature sensor
Its located on the radiator passanger side about 3" below the radiator cap.
there's no switch, it has a temperature sensor.
The engine coolant temperature sensor is the two wire sensor near where the upper radiator hose attaches to the engine.
the sensor is located next to the thermostart, driver side of the cylinder head.
The temperature sensor on a BMW 325i is located on top of the engine, near the upper radiator hose. It constantly monitors the temperature of the coolant and triggers the cooling fan as needed.
If radiator cooling fan it turns on only when temperature sensor reaches temp needed to cool car, then when enough cooling takes place, it gets told by sensor to turn off.
There is a sensor that detects temperature to turn the fan on in some vehicles, this sensor may need to be replaced.
A/C or defroster on Relay stuck in closed position Temperature sensor not sensing proper temperature
The computer uses the coolant temperature sensor to decide when to run the fans. It is below the radiator cap on the cylinder head.
The coolant temperature sensor on a Subaru is located on top of the engine near the upper radiator hose. It constantly updates the vehicles computer to regulate the speed of the cooling fan.