Air Temperature Sensor ( Ambient / Intake ): Description and Operation

MAT Sensor:

The Manifold Air Temperature (MAT) Sensor is a thermistor (resistor) whose resistance value varies in relation to the temperature of air entering the engine. Low temperature results in high resistance (100K ohms at -40°C / -40°F); high temperature results in low resistance (70 ohms at 130°C / 266°F).

The ECM supplies a 5V reference signal to the sensor and by measuring the voltage change can determine the manifold air temperature. This input is used in ECM calculations of injector pulse width ("ON" time).