Patent ID: 8210034
Filing Date: 2012-07-03
Classification: F01N,F02D,Y02T

Abstract:
1. An oxygen sensor abnormality determination apparatus comprising: a catalyst provided in an exhaust passageway of an internal combustion engine; an oxygen sensor provided in the exhaust passageway on a downstream side of the catalyst; a rich-output continuation time acquisition portion that acquires a rich-output continuation time during which an output value of the oxygen sensor continues being an output value that shows a rich state before a fuel cut is started; a first determination portion that determines whether or not the rich-output continuation time acquired by the rich-output continuation time acquisition portion is longer than a set continuation time that is set beforehand; a second determination portion that determines whether or not, after the fuel cut is started, a degree of change in the output value of the oxygen sensor when the output value of the oxygen sensor changes from a first reference value to a second reference value that shows a leaner state than the first reference value is more gradual than a set degree of change that is set beforehand; and a third determination portion that determines whether or not the oxygen sensor is abnormal based on a result of determination by the first determination portion and a result of determination by the second determination portion.