Patent ID: 8065910
Filing Date: 2011-11-29
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; an output decline acquisition portion that acquires an amount of decline in output value of the oxygen sensor during a period from when an amount of intake air declines or when an amount of exhaust gas declines before a fuel cut is started to when the fuel cut is started; a first determination portion that determines whether or not the amount of decline acquired by the output decline acquisition portion is smaller than a reference amount of decline that is set beforehand; a second determination portion that determines whether or not, after the fuel cut is started, 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.