Patent ID: 6371096
Filing Date: 2002-04-16
Classification: F02D

Abstract:
A diagnosis system comprising:a wide-range air-fuel ratio sensor detecting an air-fuel ratio of air-fuel mixture supplied to an engine; an air-fuel ratio feedback control means for correcting an air-fuel ratio controlled object on the basis of a detection result of said wide-range air-fuel ratio sensor so as to adjust the air-fuel ratio to the engine at a target air-fuel ratio; a target air-fuel ratio switching means for switching the target air-fuel ratio; a detection value variation detecting means for detecting variation of the detection value of said wide-range air-fuel ratio sensor; an abnormality diagnosing means for diagnosing said wide-range air-fuel ratio sensor on the basis of a detection result of said detection value variation detecting means during a time period from the start of the switching of the target air-fuel ratio by said target air-fuel ratio switching means; and a diagnosis control gain setting means for setting a control gain of said air-fuel ratio feedback control means at a value greater than a normal control gain when the diagnosis of said air-fuel ratio sensor is executed.