| 摘要 |
PURPOSE: To ensure a wide diagnosis area corresponding to the location without misjudging even on a higher level road and to detect accurately the abnormality of exhaust gas recirculation system by setting a diagnosis area of detecting abnormality in a range of number of revolutions of engine which is set in advance, a range of load of engine, and a range of throttle opening. CONSTITUTION: In an engine recirculating exhaust gas from an exhaust system to an intake system via an EGR passageaway 28 provided with an EGR valve 29 therebetween, when detecting abnormality of exhaust gas recirculation system of a controller, a diagnosis area is set by a range of number of revolutions of an engine which is set in advance, a range of load of the engine, and a range of a throttle opening. That is to say, in the case of driving on a lower level road the diagnosis area is set in a wide range of less than a large thresholdθth1 of the throttle opening, in the case of driving on a higher level road it is set in a narrow range of less than a small thresholdθth3 of the throttle opening (<θth1), and in the case of driving on a middle level road it is set in a range of a middle thresholdθth2 of the throttle opening (θth3<θth2<θth1).
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