Rationality check

P0120, P0121, P0221, 

The rationality check uses the measured voltages of sensor 1 and of sensor 2 to calculate the corresponding throttle position angles. The two throttle position angles are compared to each other to get deviation (synchronism) information. If the deviation between the two throttle position angles exceeds a calibrated threshold a further check is done to define which of the throttle position sensors is defective. To exactly decide which sensor is defective a theoretical reference throttle position angle is calculated with the help of the mass airflow and compared to the measured throttle position angles. If any fault of sensor 1 or of sensor 2 is set, the checks below are also performed for the error-free sensor, regardless of the synchronism result.

If the deviation of sensor 1 to reference angle is greater than the deviation of sensor 2 to reference angle (checked only without sensor fault) or

a fault of mass airflow sensor and intake manifold pressure sensor is set or

the deviation of sensor 1 to reference angle exceeds a calibrated threshold

a malfunction of sensor 1 is detected and a plausibility fault DK1P is set.

If the deviation of sensor 2 to reference angle is greater than the deviation of sensor 1 to reference angle (checked only without sensor fault) or

a fault of mass airflow sensor and intake manifold pressure sensor is set or

the deviation of sensor 2 to reference angle exceeds a calibrated threshold

a malfunction of sensor 2 is detected and a plausibility fault DK1P is set.

Additionally a plausibility summary fault DK is set.