Intake Air Temperature (IAT) Sensor
The IAT sensor is a thermistor device in which resistance changes with temperature. The resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor pins and provides electrical signals to the PCM corresponding to temperature.
Thermistor type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.
The IAT sensor provides air temperature information to the PCM. The PCM uses the air temperature information as a correction factor in the calculation of fuel, spark, and airflow.
The IAT sensor provides a quicker temperature change response time than the ECT or CHT sensor.
Currently there are 2 types of IAT sensors used, a stand alone and an integrated type. Both types function the same, however the integrated type is incorporated into the mass airflow (MAF) sensor, the manifold absolute pressure and temperature (MAPT) sensor, or the turbocharger intake pressure and temperature (TCIPT) sensor instead of being a stand alone sensor.
The IAT2 sensor is centrally located on the intake manifold and is used to measure the intake manifold temperature. The PCM uses this information to determine the air charge and provide input for various engine control functions. The IAT2 sensor is integrated with the manifold absolute pressure (MAP) sensor.
The Ford GT uses 2 integrated MAF/IAT sensors, a bank 1 and a bank 2 sensor. The bank 1 sensor is used for most diagnostics and engine control functions. Each sensor provides data to the PCM that is used for diagnostics related to the dual intake air system configuration. The sensors are located on opposite sides of the vehicle in the duct next to the air filter.