Code 25 (1.6L Turbo) - Manifold Air Temperature (Mat) Sensor Circuit (High Temperature Indicated): Notes

The MAT sensor uses a thermistor to control signal voltage to the ECM. The ECM applies 4-6 volts on Blue/Black wire to MAT sensor. When manifold air is cold, sensor resistance is high and ECM will see a high voltage. As air temperature increases, sensor resistance decreases and the voltage drops.

1. This determines if Code 25 is the result of a hard failure or an intermittent condition. Code 25 will set if MAT temperature is greater than 293°F (145°C) for more than 2 minutes.