Camaro V8-5.7L VIN G (1998)
Intake Air Temperature Sensor: Description and Operation
Intake Air Temperature (IAT) Sensor
DESCRIPTION
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 -38°C/-39°F). A high temperature causes low resistance (70 ohms at 130°C/266°F).
OPERATION
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. The PCM calculates the incoming air temperature by measuring the IAT voltage. 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. The following DTCs set if the PCM detects a malfunction in the AT
sensor circuit:
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DTC P0112 AT Sensor Circuit Low Voltage.
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DTC P0113 AT Sensor Circuit High Voltage.
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DTC P1111 IAT Sensor CKT Intermittent High Voltage.
^
DTC P1112 AT Sensor CKT Intermittent Low Voltage.
