| abstract |
In an internal combustion engine, in an engine exhaust passage, a solid electrolyte (61), electrodes (62, 63) covering both side surfaces of the solid electrolyte (61), and a diffusion resistance layer (64) covering one electrode (63), respectively. An air-fuel ratio sensor (23, 24) having When the air-fuel ratio of the exhaust gas changes and the air-fuel ratio detected by the air-fuel ratio sensor (23, 24) changes, the change in the air-fuel ratio detected by the air-fuel ratio sensor (23, 24) changes. , 24) depends on the amount of sulfur component adhering to the air-fuel ratio sensor (23, 24). As the amount decreases, the air-fuel ratio change period increases. The sulfur poisoning amount of the air-fuel ratio sensor (23, 24) is detected from the change of the air-fuel ratio detected by the air-fuel ratio sensor (23, 24). |