The engine cooling temperature sensor is a thermistor that modifies its resistance as the temperature changes. It is screwed into the intake manifold coolant passage on 4-cylinder and 3.3 L V6 models, and into coolant pipe on 3.5 L V6 models. The sensor senses coolant temperature and this information is used by the PCM to compute the engine operating temperature. A problem in the sensor circuit can set a trouble code due to wiring or connection issues or a faulty sensor. Therefore it is important to first check for voltage supply and ground circuits from PCM before checking the sensor. In case voltage supply is not correct, check wiring; if not inspected, PCM may be needed in this case. The resistance between two terminals of this sensor can be measured with ohmmeter. Replace it if the resistance test results are not right.If you replace it, wrap Teflon sealing tape around threads to prevent leakage and corrosion.The old one should be disconnected and removed quickly replaced with new one to minimize coolant loss.They should tightly secure the sensor and reconnect electrical connector. Check coolant level to see whether it needs filling up with coolant or not.Starting engine and allowing it reach normal operating temperature means checking for any leakage of coolant.Coolant level in expansion tank should also be checked after engine has both warmed up and cooled down.