Rationality checks

P0127, P111E, P111F, P0111 

To determine, whether the intake air temperature is in a plausible range, several checks are performed.

The high side check monitors, depending on mass airflow and vehicle speed, whether the measured intake air temperature exceeds a calculated maximum temperature. If the measured intake air temperature exceeds the calculated maximal temperature while the monitoring conditions are fulfilled, a maximum fault TAR will be set.

The stuck check monitors the rise or drop behavior of the intake air temperature during a calibrated number of engine operation condition changes.

If the difference of the minimum and maximum measured intake air temperature lies below a calibrated threshold, a plausibility fault TAR will be set.

The low side check monitors the difference between the engine coolant temperature and the intake air temperature when the engine is cooled down. For a cooled down engine both temperatures must be nearly equal for a short time after start. If the absolute difference between engine temperature and intake air temperature exceeds a calibrated threshold for a calibrated period of time, a fault TACS will be set.