Method of diagnosing exhaust gas recirculation (EGR) in IC engine e.g. petrol engine, involves determining storage capacities of catalyst during closed and open EGR, and comparing both capacities for EGR abnormalities

摘要

A storage catalyst (12) is located downstream of an exhaust pipe (11) connected to an EGR line (21). The EGR line is connected to an air intake pipe (31). The storage capacities of the storage catalyst during open and closed EGR operations are determined and then compared. Abnormality of EGR operation can be determined based on the difference between storage capacities.