Temperature Sensor (Gauge): Testing and Inspection

The engine coolant temperature sender is a thermistor, in which resistance decreases as engine coolant temperature increases. The sender operates the engine coolant temperature gauge.

1. Turn ignition switch to On position.
2. Disconnect engine coolant temperature sender, then ground YEL/BLK wire.
3. If coolant temperature gauge does read hot, proceed to next step.
4. Remove engine coolant temperature sender.
5. Place sender in water, then heat water slowly and check resistance of the sender with ohmmeter.
6. If resistance is not 190-260 ohms at 122 °F, then replace engine coolant temperature sender.