| 摘要 |
<P>PROBLEM TO BE SOLVED: To diagnose with high accuracy in consideration of reduction performance of a NOx catalyst. <P>SOLUTION: First storage capacity after occluded NOx is released is measured on condition that the temperature of the NOx catalyst is a predetermined temperature or above. Second storage capacity after the occluded NOx is released is measured by supplying stoichiometric or rich exhaust gas to the NOx catalyst on condition that the temperature of the NOx catalyst is lower than the predetermined temperature. The measured first storage capacity is compared with a predetermined determining value X, and it is determined whether the NOx catalyst is normal or deteriorated. The determining value X is set based on the measured first storage capacity and second storage capacity. Since the determining value is set based on the second storage capacity representing the reduction performance of the NOx catalyst, it is possible to diagnose with high accuracy in consideration of the reduction performance of the NOx catalyst. <P>COPYRIGHT: (C)2011,JPO&INPIT |
