ABNORMALITY DIAGNOSIS APPARATUS FOR EXHAUST GAS RECIRCULATION APPARATUS AND ABNORMALITY DIAGNOSIS METHOD FOR EXHAUST GAS RECIRCULATION APPARATUS

摘要

An EGR apparatus (20) includes an EGR passage (21) that connects an intake passage (11) and an exhaust passage (13) of an internal combustion engine (10) in order to introduce a part of an exhaust gas into the intake passage (11), and an EGR valve (22) for adjusting the amount of exhaust gas flowing through the passage (21). An oxygen concentration sensor (54) that outputs a continuous value corresponding to the oxygen concentration of the exhaust gas flowing through the exhaust passage (13) is provided in the exhaust passage (13). Valve-opening driving is performed on the EGR valve (22) during fuel cut processing for halting the fuel supply of the internal combustion engine (10), and when a variation range of the output value of the oxygen concentration sensor (54) accompanying the valve-opening driving is smaller than a predetermined value, it is determined that an abnormality is present in the EGR apparatus (20).