Theory of Operation

WARNING: This page is about a different car, the 2011 RAM Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Intake Air Temperature (IAT) Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.The IAT sensor is a variable resistor that measures the ambient air temperature. The Powertrain Control Module (PCM) supplies a 5 Volt reference and a ground to the sensors low reference signal circuit. When the IAT is low, the sensor resistance is high. When the IAT is high, the sensor resistance is low.