Fuel System Monitoring

General Description

The fuel system monitoring includes the lambda controller restriction against the limits for rich and lean and the permanent deviation from the mean position.

Monitoring Structure

If the fuel system is suddenly hard disturbed and therefore the lambda controller reaches the restriction (Lmax/Lmin) a timer is started. The timer is incremented as long as the controller remains at the limit. If the timer exceeds a predetermined value a fault for short trim will be detected and stored for rich and lean exceeding separately.

For permanent deviation from the mean position there are additional lean and rich thresholds (Tlmax/Tlmin). If the accumulated time (sum of all excesses for rich or lean) is greater than a fixed limit during a defined period a fault for long term trim will be detected and stored for rich and lean exceeding separately.

Monitoring Conditions





- closed loop conditions
- evaporative purge amount < below a defined percentage of lambda deviation