Nissan 22630-51E00 Engine Coolant Temperature Sensor

The coolant temperature indicator system consists of a temperature gauge mounted in the instrument panel and a coolant temperature sending unit mounted in the water passage on the timing belt end of the lower intake manifold. There is more than one temperature sensor, but only one is used for the indicator system. If an overheating indication occurs even when the engine is cold, check the wiring between the dash and the sending unit for a short circuit to ground. If the gauge is inoperative, test the circuit by briefly grounding the wire to the sending unit while the ignition is On (engine not running for safety). If the gauge deflects full scale, replace the sending unit. If the gauge doesn't respond, check for an open circuit in the gauge wiring. To test the sending unit, disconnect the electrical connector and attach an ohmmeter from the pin on top of the sender to an engine ground. With the engine warm (167 degreesresistance should be 179 to 219 ohms. When the engine is hot (212 degrees F), the resistance should drop to 60 to 72 ohms. If the sender fails the test, replace it. If the sending unit must be replaced, unscrew it from the engine and quickly install the replacement. Use a conductive sealant on the threads (not Teflon tape). Make sure the engine is cool before removing the defective sending unit. There will be some coolant loss as the unit is removed, so be prepared to catch it. Check the coolant level after the replacement part has been installed.