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

Manifold Air Temperature (MAT) sensor uses a thermistor to control signal to ECM. ECM applies 4-6 volts to circuit No. D7 of sensor. When manifold air is cold, sensor resistance is high and ECM will see a MAT signal. As air warms, sensor resistance is low and MAT signal drops.

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