| 摘要 |
A catalyst deterioration diagnostic device for a multiple-cylinder internal combustion engine including a first cylinder group having exhaust system that is equipped with an exhaust gas recirculation (EGR) device with an EGR catalyst and a second cylinder group having exhaust system that is not equipped with the EGR device. The catalyst deterioration diagnostic device implements active air-fuel ratio control to diagnose deterioration of a main catalyst. During the active air-fuel ratio control, the catalyst deterioration diagnostic device oscillates only a target air-fuel ratio of the second cylinder group, without oscillating a target air-fuel ratio of the first cylinder group, in a case where the EGR device is stopped. |
