| 摘要 |
PROBLEM TO BE SOLVED: To prevent an O<SB>2</SB>sensor from being erroneously determined by evaporator gas purge as to whether it is normal in a vehicle having a self-diagnosing function performing the abnormality diagnosis of the O<SB>2</SB>sensor (exhaust gas sensor) and an engine gas purge system. SOLUTION: The abnormality diagnosis of the O<SB>2</SB>sensor is prohibited until a predetermined time is elapsed from the start of evaporator gas purge when the learned value of an evaporator gas concentration used as the detected information of the evaporator gas concentration is equal to or higher than a predetermined value K1. When the amount of variation of an evaporator gas purge amount within a predetermined time is equal to or higher than the predetermined value K2, the abnormality diagnosis of the O<SB>2</SB>sensor is prohibited. When the learned values of an air-fuel ratio correction values used before and after the change of an engine operation area when the engine operation area is changed, is changed by a predetermined value K3 or higher, the abnormality diagnosis of the O<SB>2</SB>sensor is prohibited. COPYRIGHT: (C)2008,JPO&INPIT
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