DTC P0117: Coolant Temp Sensor Low Temp Indicated: Notes

ECT sensor uses a thermistor to control signal voltage to PCM. PCM applies and monitors a 5-volt reference signal to sensor. When engine coolant is cold, sensor (thermistor) resistance is high and PCM will sense a high signal voltage. As engine coolant increases, sensor resistance becomes less and PCM voltage drops.

1. Determines if conditions necessary to set Code P0117 exist.
2. Determines if sensor signal circuit is shorted to ground.