Remove the coolant temperature sensor to check or replace it.
Checking the sensor is shown in the section Troubleshooting.
When the sensor is unscrewed, fluid will leak from the cooling system, so we drain the coolant from the engine (see Coolant replacement).
With the ignition off..
... we press the clamp of the block of the wiring harness of the engine management system..
... and disconnect the wiring harness block from the sensor.
With a 19" spanner, unscrew the sensor and remove it.
The connection between the sensor and the cylinder head is sealed with a copper washer.
If damaged, replace the washer with a new one.
Install the coolant temperature sensor in reverse order.
Fill the engine with coolant.