Intake Air Temperature (IAT) Sensor

The Intake Air Temperature (IAT) sensor is a thermistor (temperature sensitive resistor). Air temperature of -40°F (-40°C) sensor produces a high resistance (100 k/ohms), while air temperature of 266°F (130°C) sensor produces a low resistance (70 ohms).

PCM supplies and monitors a 5-volt reference signal through an internal resistor to IAT sensor and measures return voltage. Voltage is high when temperature is low, and low when temperature is hot. Engine air temperature affects fuel delivery and injector timing.