| 摘要 |
PROBLEM TO BE SOLVED: To specify an abnormal region causing an abnormality when an abnormality (abnormality in air-fuel ratio) occurs in a control system of an internal combustion engine. SOLUTION: An "abnormality diagnosis of an air fuel ratio control system" for determining whether there is an abnormality in an air-fuel ratio control system as an abnormality in a first level, is executed. When an abnormality in the air-fuel ratio control system (abnormality in air-fuel ratio) is detected, so as to specify the abnormal region, an "abnormality diagnosis of an EGR system 36" for determining whether there is an abnormality in the EGR system 36, and an "abnormality diagnosis of a purge system 41" for determining whether there is an abnormality in the purge system 41, are executed as an abnormality in a second level. As a result, when it is determined that there is an abnormality in the EGR system 36, the EGR system 36 is specified to be the cause of the abnormality of the air-fuel ratio, and when it is determined that there is an abnormality in the purge system 41, the purge system 41 is specified to be the cause of the abnormality in the air-fuel ratio. COPYRIGHT: (C)2008,JPO&INPIT
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