FILTER FAILURE DETERMINING SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a filter failure determining system for timely performing the failure determination of a filter.SOLUTION: The filter failure determining system performs the failure determination of the filter on the basis of an estimated accumulation amount of particulate matters estimated by a PM accumulation estimating unit and an exhaust pressure difference detected by a differential pressure sensor. When predetermined conditions for the particulate matters trapped by the filter to be oxidized by NOin exhaust gas are established, the execution of the failure determination is allowed if an integrated PM oxidization amount showing how much the particulate matters trapped by the filter are oxidized by the NOin the exhaust gas since the predetermined conditions are established, is smaller than an allowable PM oxidization amount. The allowable PM oxidization amount is calculated on the basis of the estimated accumulation amount of the particulate matters estimated by the PM accumulation estimating unit when the predetermined conditions are established.