Diagnosis system for wide-range air-fuel ratio sensor

摘要

A diagnosis system for a wide-range A/F sensor receives an air-fuel ratio (A/F) of air-fuel mixture supplied to an engine for the A/F sensor. An control unit of the diagnosis system corrects an A/F controlled object of a feedback control on the basis of a detection result of the A/F sensor to adjust the A/F at a target A/F. The control unit diagnoses an abnormality of the A/F sensor from variation of the detection value of the A/F sensor during a time period from the start of the switching of the target A/F. The control unit sets a control gain of an A/F feedback control at a value greater than a normal control gain during the diagnosis.