| 摘要 |
PROBLEM TO BE SOLVED: To purge evaporated gas without substantially deteriorating emission, even when abnormality is caused in a catalyst upstream side exhaust gas sensor. SOLUTION: The exhaust gas sensors 24 and 25 are respectively arranged on the upstream side and the downstream side of an exhaust emission control catalyst 23, and the air-fuel ratio is controlled by making a feedback process based on output of at least the upstream side exhaust gas sensor 24, and the evaporated gas is purged in an intake pipe 12 from a canister 34 in response to an engine operation state. When detecting the abnormality of the upstream side exhaust gas sensor 24, air-fuel ratio feedback control based on the output of the upstream side exhaust gas sensor 24 is stopped, and evaporated gas purge control at normal time is also stopped. Instead of it, the evaporated gas is purged by starting current-carrying to a purge control valve 36 when a predetermined abnormal time purge performing condition is realized in a period when the output of the downstream side exhaust gas sensor 25 becomes lean. COPYRIGHT: (C)2009,JPO&INPIT
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