Circuit Description

Intake Air Temperature (IAT) sensor is a thermistor, which varies resistance based on temperature. As temperature of sensor increases, resistance decreases. Low temperature will result in a high signal voltage. DTC will set when PCM senses IAT sensor voltage is greater than 5 volts.

Conditions required to set DTC are:

• Engine running for more than 4 minutes.
• Vehicle speed is less than 20 MPH.
• MAF value is less than 20 grams per second.
• ECT signal temperature is greater than 140°F (60°C).
• IAT signal voltage indicates an intake air temperature less than -38°F (-39°C) for 12.5 seconds over a 25-second period.