Air Temperature Sensor ( Ambient / Intake ): Description and Operation
DESCRIPTIONThe Intake Air Temperature (IAT) sensor is a thermistor (a resistor which changes value based on temperature). It is mounted in the air intake duct. Low temperature produces a high resistance (100,000 ohms at 40°C / -40°F), while high temperature causes low resistance (70 ohms at 130°C / 266°F).
OPERATION
The Engine Control Module (ECM) supplies a 5 volt signal to the sensor through a resistor in the ECM and measures the voltage. The voltage will be high when the intake air is cold, and low when the intake manifold air is hot. By measuring the voltage, the ECM knows the intake air temperature. A failure in the IAT sensor circuit should set either a DTC 23.