1.15.8.2 Rationality checks

P0127 (TARmax), P0111 (TARnpl), P111E (TACSmax), P111F (TACSmin) 

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 TARmax fault 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 TARnpl fault will be set.

The low side check monitors the difference between the intake air temperature and the engine coolant temperature during engine start. For a cooled down engine both temperatures must be nearly equal for a short time after start.

If the difference between intake air and engine coolant temperature exceeds a calibrated threshold, a TACSmax fault will be set.

Else, if the difference of engine coolant and intake air temperature exceeds a calibrated threshold, a TACSmin fault will be set.