ESP_a138_steeringAngleImplaus

Not Available

What does the ESP_a138_steeringAngleImplaus alert mean?

Steering Wheel Position Sensor: Plausibility fault

What triggers it

The monitoring checks for a physically plausible steering angle signal and consists of following parts:- Sas range monitoringReceived raw sensor hardware value is higher than the maximum, physical steering wheel turn from zero-position to lock in the vehicle (LwAnschlMax) + an additional robustness tolerance value (typical 90 deg)- Sas gradient monitoringIf the signal gradient (steering angle velocity) from one 20 ms-cycle to another is higher than 40 deg for 2 SAS Messages (60 deg for more than 2 SAS messages or no SAS message counter) or - change of this gradient (steering angle acceleration) is higher than 30 deg a failure will be set.- Sas plausibility versus yaw rateThe difference between measured steering angle signal and model value calculated from yaw rate signal is evaluated for fault detection. Dependent on the driving conditions failures in size of (10 + 60 [m/s] / velocity [m/s]) deg at steering angle are recognized through three possible recognition paths evaluating stable driving conditions. This is to prevent a fault recognition due to unstable driving.When the difference is caused by a fault of the steering angle sensor a steering sensor angle fault will be entered. The sensor - yaw rate sensor(YRS) or steering angle sensor(SAS) - showing the largest deviation to the reference yaw rate is marked as faulty.

When it clears

Verify EPAS is awake, in good state, and there is traffic present on the bus. Review EPAS/DI alerts for other indicators of failure

Potential impact

May fault VDC/TC, ABS performance degradation

Affected models