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

IAT sensor uses a thermistor to control signal voltage to ECM. ECM applies 4-6 volts on Red/Black wire to sensor. When intake air is cold, sensor resistance is high. ECM will sense high signal voltage. As intake air temperature warms, sensor resistance decreases, and voltage drops.

Code 23 will set if voltage input at ECM indicates an air temperature below 52°F (-47°C) for at least 5 seconds.

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

This test simulates Code 25. If ECM stores Code 25, ECM and its wiring are okay, and IAT sensor is faulty. If Code 23 resets, IAT sensor is okay, and wiring to ECM or ECM is faulty.
This test determines whether there in an open in the Red/Black or Gray/Yellow wires, a short to B+ in the Red/Black wire or a faulty ECM.