POST UPDATED IN October, 2021
The Multiple Air Temperature Sensor, or MAT, is a thermistor that is located at the junction of the air filter, and thus allows the ECM (Engine Control Module) to balance exactly the air flow readings, all this is done based on the temperature of the incoming air. Its behavior is similar to that of the Input Air Temperature Sensor (IAT), except that they have different positions, but they have a similar function: To study the air temperature.
The MAT sensor has 2 wires, one ground and the other signal and the pull up voltage. Also note that this sensor is connected to terminals F16 and E5 of the Engine Control Module (ECM). It has a variation of internal resistance that is precise; in addition, its position serves to have a good estimate of the air entering through the manifold.
The Multiple Air Temperature sensor (MAT) converts the temperature into a reference signal. Terminal E5 is connected to ground inside the ECM and thus obtains an accurate reading. In turn, the ECM, through terminal F16, sends a reference voltage of 5 volts of little regulated amperage with the help of a resistance that goes inside.
When the air temperature rises, the resistance drops, when this happens the Engine Control Module (ECM) determines that there is a low voltage through the terminal F16, so it adapts the operation of the engine.
At the moment when the engine is cold, the resistance of the Multiple Air Temperature Sensor (MAT) increases, so the ECM detects that the voltage is high and modifies the operation of the engine, so that it is the most suitable cold.