Procedure for determining offset signal value from NOx detector in IC engine exhaust system, uses signal values taken during stoichiometric operating mode

摘要

The procedure, designed to determine the offset value of a signal from a NOx detector (9, 10) positioned after an IC engine consists of operating the engine with a stoichiometric relationship of air and fuel (lambda = 1), with the signal taken during a stoichiometric operating mode and the offset value taken as a representative value of the values determined and authorized if the authorization conditions are fulfilled. In the event of one or more authorization conditions not being fulfilled the determination of the signal values does not take place or is interrupted. The verification of the authorization conditions is effected before the signal values are determined, and the offset signal value is effected only after a predetermined time has elapsed following the verification of the authorization conditions.