Code 23, Intake Air Temp Sensor CKT Low Temp Indicated
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 the intake air warms, the sensor resistance becomes less, 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 engine has been running longer than 2 minutes and signal voltage indicates IAT temperature is less than -22°F (-30°C).
- Simulates conditions for a Code 23 (high temperature indicated). If Scan tester displays a high temperature, ECM and wiring are okay.
- Checks continuity of Blue/Black and Black wires. If Black wire is open, a Code 21 may also be present.