In the engine situated at the left area is where a coolant temperature sensor is located. First remove the engine cover and air intake duct, then drain some coolant from the engine to reduce spillage of coolant. After that, disconnect electrical connector from ECT sensor by depressing the tab on electrical connector. Remove the sensor and discard the washer, as a fresh one should be fitted. To have it fixed back follow what you did when you removed it. Lastly recharge your cooling system.