Intake Air Temperature Sensor
The 2-wire IAT sensor is installed in the intake manifold with the sensor element extended into the air stream. See Fig 1 -Fig 3 . The IAT sensor is a 2-wire Negative Thermal Coefficient (NTC) sensor. As intake air temperature increases, voltage decreases. As intake air temperature decreases, voltage increases. The IAT sensor provides an input voltage to the PCM indicating intake air density based on temperature. At key-on, a 5-volt power circuit is supplied to the sensor from the PCM. The sensor is grounded at the PCM through a low-noise, sensor-return circuit. The PCM uses this input to calculate fuel injector pulse width and ignition timing spark advance (to help prevent spark knock with high intake manifold air-charge temperatures. The resistance values are the same as the Engine Coolant Temperature (ECT) sensor.