Grand Prix V6-3.8L SC VIN 1 (1997)
Intake Air Temperature: 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 ohms at -40°C/-4O°F), while high temperature causes low resistance (70 ohms at 130°C/266°F)
. The PCM supplies a 5 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 engine is cold, and rise as 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 or DTC P0113.
