Reference signal check

P0327, P1327, P0328; P1328, P1329, P1330, P033C, P033D 

A reference signal is calculated based on the knock sensor signal. This reference value represents the basic noise of the current sensor being analyzed. When the monitoring conditions are fulfilled, A refernce signal is compared with the lower and upper calibrated engine-speed-dependent thresholds and detected faults are counted.

If the fault counter exceeds a calibrated threshold and Uref lies below the lower calibrated threshold, (for a calibrated period of time) a malfunction is detected and a minimum fault KSx is set.

If the fault counter exceeds a calibrated threshold and Uref exceeds the upper calibrated threshold, (for a calibrated period of time) a malfunction is detected and a maximum fault KSx is set.

The fault path is cleared when the current reference level for a calibrated number of successive checks again lies within the range bounded by the upper and lower calibrated reference thresholds (for a calibrated period of time).