The intake air temperature (IAT) sensor is a thermistor which measures the temperature of the air entering the engine. The powertrain control module (PCM) applies 5 volts through a pull up resistor. When the intake air is cold, the sensor resistance is high and the PCM will monitor a high signal voltage on the IAT sensor signal circuit.
As the intake air warms, the sensor resistance becomes lower causing the PCM to monitor a lower voltage. If the PCM detects an excessively low IAT sensor signal voltage, high temperature indicated, DTC P0112 will set.
If the PCM detects an excessively high IAT sensor signal voltage, a low temperature is indicated, and DTC P0113 will set.
The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure.
The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Be sure to pull on each of the wires right at the sensor connector. A common failure is broken wires. Pull on them to see if they stretch or break.
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