MALFUNCTION DIAGNOSTIC DEVICE FOR EXHAUST GAS CONTROL DEVICE

摘要

A malfunction diagnostic device for an exhaust gas control device includes: a malfunction determination unit that determines an exhaust gas control device provided in an exhaust system of an internal combustion engine malfunctions when a parameter that indicates exhaust gas purification performance of the exhaust gas control device crosses a threshold; a deterioration determination unit that determines the degree of deterioration of the exhaust gas control device; and a variable threshold setting unit that variably sets the threshold based on the degree of deterioration of the exhaust gas control device in such a manner that the likelihood that the exhaust gas control device is determined to be malfunctioning is lower at lower degrees of deterioration of the exhaust gas control device.