Grand Prix V6-3.1L VIN J (2000)
Intake Air Temperature (IAT) Sensor: Description and Operation
The Intake Air Temperature (IAT) sensor is a thermistor which changes value based on the temperature of air entering the engine. Low temperature
produces a high resistance (100,000 Ohm at -40°C/-40°F), while high temperature causes low resistance (70 Ohm at 130°C/266°F).
The PCM supplies a 5.0 volt signal to the sensor through a resistor in the PCM and measures the voltage. The voltage will be high when the incoming air
is cold, and low when the air is hot. By measuring the voltage, the PCM calculates the incoming air temperature. The IAT sensor signal is used to adjust
spark timing according to incoming air density.
The scan tool displays temperature of the air entering the engine, which should read close to ambient air temperature when the engine is cold, and rise as
the underhood temperature increases.
If the engine has not been run for several hours (overnight) the IAT sensor temperature and engine coolant temperature should read close to each other.
A failure in the IAT sensor circuit should set DTC P0112 In take Air Temperature (IAT) Sensor Circuit Low Voltage or DTC P0113 In take Air
Temperature (IAT) Sensor Circuit High Voltage.
