Check the Air Temperature Reading
Allow the engine to run until it is warm. Use a scan gauge to compare the air temperature reading to the coolant temperature. Typically, a functional IAT sensor will report a slightly lower temperature than the coolant temperature sensor.
Examine Wiring Between the PCM and IAT
This error can be caused by wiring that has come loose or corroded, so examine the physical circuit between the IAT and the vehicle’s computer.
Test the Resistance
First, remove the IAT from the vehicle. Using an ohmmeter, measure the resistance of the IAT at room temperature. Then apply heat to the IAT sensor tip with a hair dryer and check to see if the resistance has decreased. No change in resistance or an infinite resistance reading indicate that the IAT sensor is faulty.