ABNORMALITY DIAGNOSIS SYSTEM OF AIR-FUEL RATIO SENSOR

摘要

An abnormality diagnosis system of an air-fuel ratio sensor 40 or 41 acquires a blowby gas flow ratio showing a ratio of the flow of blowby gas to the flow of gas to a combustion chamber 5 and an output current of an air-fuel ratio sensor 40 or 41 during fuel cut control in which an internal combustion engine stops the feed of fuel to the combustion chamber 5 and at a plurality of points of time of different flows of blowby gas passing through a blowby gas passage 25 and flowing to the downstream side of a throttle valve 17 in the intake passage, calculate an output current of the air-fuel ratio sensor 40 or 41 corresponding to a blowby gas flow ratio smaller than the blowby gas flow ratios acquired at the plurality of points of time, based on the acquired blowby gas flow ratio and output current, and judge the air-fuel ratio sensor 40 or 41 for abnormality based on the calculated output current.