Theory Of Operation
WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The Intake Air Temperature (IAT) Sensor diagnostic, under cold start conditions, following a start to run delay time, compares the values of the Ambient, Engine Coolant, and Intake Air Temperature Sensors. If the Engine Coolant Temperature (ECT) and Ambient Air Temperature (AAT) Sensors agree and the IAT Sensor does not agree, the IAT Sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle.