Diagnostic apparatus for exhaust gas clarification apparatus for internal combustion engine
A diagnostic apparatus for exhaust gas clarification apparatus for internal combustion engine is disclosed. The diagnostic apparatus can diagnoses the individual catalyst independently by means that an air/fuel ratio sensor is mounted before and after the individual catalyst, and that the individual catalyst is diagnosed by estimating the correlation of the output signals from the air/fuel ratio sensors mounted before and after the individual catalyst, and furthermore, that the individual diangosis operation is performed at distinctive operation regions adequate for their corresponding diagnostic mode.