Code 23, Intake Air Temp Sensor CKT, High Temp Indicated: Notes

The IAT sensor uses a thermistor to control signal voltage to ECM. ECM applies 4-6 volts on Blue/Black wire to sensor. When intake manifold air is cold, the sensor (thermistor) resistance is high and the ECM senses a high voltage. As intake air warms, sensor resistance drops, and voltage drops.

NOTE: Test numbers refer to test numbers on diagnostic chart.

This checks if Code 23 is due to a hard failure or an intermittent condition. Code 23 is set if IAT temperature is greater than 390°F (199°C) for more than 2 seconds.