Code 24, Manifold Air Temperature (Mat) Sensor Circuit Low Temperature Indicated: Notes

The MAT sensor uses a thermistor to control the signal voltage at the ECM. The ECM applies 4-6 volts to the sensor. When air is cold, thermistor resistance is high, so ECM sees a high signal voltage. If air is warm, sensor resistance is low, so ECM sees a low voltage.

1. This verifies 4-5 volts are present at MAT sensor connector.
2. This checks ground side of MAT sensor circuit.
3. This determines if problem is caused by an open circuit or ECM.
4. This determines if Black wire (VIN 5) or Yellow/Black wire (VIN 6) is open or if ECM is defective.