| 摘要 |
PROBLEM TO BE SOLVED: To provide an abnormality diagnosis device for an internal combustion engine which is a device provided with an air fuel ratio sensor in an upstream and a downstream of a catalyst of an internal combustion engine and executing air fuel ratio feed back control by air fuel ratio sensor output and which materializes accurate abnormality diagnosis of a fuel system abnormality of the internal combustion engine by using signals of a catalyst downstream side air fuel ratio sensor. SOLUTION: A feed back operation state judgment means 32, an O2 storage saturation judgment means 33, an averaging start judgment means 34, an averaging means 35 and an abnormality judgment means 36 are provided in ECU 30 constructing the control device. Fuel system abnormality of the internal combustion engine is judged by using second air fuel ratio signal V2 detected by a second air fuel ratio sensor in a catalyst downstream side only when O2 storage quantity of the catalyst is saturated. COPYRIGHT: (C)2008,JPO&INPIT
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