Code 25, Manifold Air Temperature (Mat) Sensor Circuit High Temperature Indicated: Notes

MAT sensor uses a thermistor to control signal voltage to the ECM. The ECM applies 4-6 volts on Gray wire to the sensor. When manifold air is cold, sensor resistance is high. This means ECM will see high signal voltage. As air temperature warms, sensor resistance reduces and voltage drops.

1. Code 25 will set if signal voltage indicates air temperature greater than 277°F (136°C) for 2 seconds.
2. If resistance is less than 100 ohms, replace sensor.