Code 22, Coolant Temperature Sensor, Open Or Shorted Circuit: Notes

The Coolant Temperature Sensor (CTS) uses a thermistor to control signal voltage to ECM. ECM applies voltage on White wire to the sensor. When engine is cold, thermistor resistance is high. ECM will sense high signal voltage.

As engine warms, thermistor resistance decreases. ECM will sense low signal voltage. When engine reaches normal operating temperature, signal voltage will be about 1.5-2.0 volts at ECM.

1. Verifies 4-5 volts is present at CTS connector.
2. Checks ground side of CTS circuit.
3. Determines if problem is caused by an open Brown wire or the ECM. Ensure ECM connectors fit properly.