Roadmaster Estate Wagon V8-350 5.7L VIN P SFI (1996)
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 ohms at -40°C/-40°F). A high temperature causes low resistance (70 ohms 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 engine is cold. The
temperature should 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. If the PCM detects a malfunction in the IAT sensor circuit, the
following DTCs will set:
^
DTC P0112 circuit low.
^
DTC P0113 circuit high.
^
DTC P1111 circuit intermittent high.
^
DTC P1112 circuit intermittent low.
LEGEND
(1) Intake Air Temperature (AT) Sensor
(2) Electrical Harness Connector
