Monitor Strategy Description

To fulfill the legal requirements of the OBDII lambda sensor diagnosis, the trim of the lambda control by the lambda sensor signal downstream of the catalytic converter must be monitored in addition to the diagnosis of the lambda sensor upstream of the catalytic converter (by determining the switching times and the control frequency). Faulty behavior of the lambda sensors upstream or downstream the catalytic converter exists if sensor limits are reached and in this way one of the emission values in the FTP test is exceeded by 1.5 fold.