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

INTAKE AIR TEMPERATURE SENSOR

DESCRIPTION
The Intake Air Temperature (IAT) sensor is a thermistor (a variable resistor that changes along with temperature changes) in series with a fixed resistor within the Engine Control Module (ECM), that measures the temperature of the air entering the intake manifold.

OPERATION
The ECM applies 5 volts to the sensor. The ECM monitors the voltage across the IAT sensor and converts it into a temperature reading. When the outside air temperature is cold, the IAT sensor resistance is high, and when the outside air temperature is warm, the IAT sensor resistance is low. Therefore, when the air temperature is cold the ECM will receive a high voltage input, and when the air temperature is warm the ECM will receive a low voltage input. The IAT sensor is located on the Air Cleaner (ACL) as shown in the accompanying image.