Regal V6-191 3.1L VIN M SFI (1995)
Intake Air Temperature Sensor: Description and Operation
Intake Air Temperature Sensor
Intake Air Temperature Sensor Wiring Schematic
PURPOSE
The Intake Air Temperature (IAT) sensor measures the temperature of the intake air in the air cleaner. The IAT is a thermistor (a resistor which
changes value based on the temperature of air entering the engine) and is mounted in the air cleaner assembly.
OPERATION
Low intake air temperature produces a high IAT sensor resistance, while high intake air temperature produces a low resistance. The Powertrain
Control Module (PCM) supplies a 5 volt signal to the sensor through a resistor in the PCM and measures the voltage. The measured voltage varies
with the temperature of the intake air, due to the changing resistance of the sensor. By measuring the voltage, the PCM calculates the intake air
temperature. The PCM uses this information to control spark timing, air / fuel ratio and delays Exhaust Gas Recirculation (EGR) when the intake
air is cold.
NOTE: A failure in the IAT sensor circuit should set either a Diagnostic Trouble Code (DTC) 23 or DTC 25. Once a DTC is set, the PCM will
use an artificial default value for IAT and some vehicle performance will return.
