Set Conditions

Once the vehicle is soaked for a calibrated engine off time and then driven over calibrated speed and load conditions for some calibrated time, the PCM compares the ambient, engine coolant, and intake air temperature sensor values. If ambient air and intake air temperature sensors agree with each other but engine coolant temperature does not agree with them, the engine coolant temperature sensor is declared as irrational. Two Trip Fault. Three good trips to turn off the MIL.