Code 23B - Mat Circuit (High Temperature Indicated): Notes

Manifold Air Temperature (MAT) sensor uses a thermistor to control signal to ECM. ECM applies and monitors 4-6 volts to sensor. When manifold air is cold, sensor resistance is high, the ECM will see a high MAT signal. As air warms, sensor resistance drops and MAT signal drops.

1. Code 23B will set if engine has been running for longer than 3 minutes and a MAT greater than 302°F (150°C) is detected.