| 摘要 |
<p>PURPOSE:To exactly judge the existance of the deterioration of a catalyst, even if the deterioration of an air-fuel ratio sensor itself brings about the change of the characteristic of its output, in the case where the feedback control of air-fuel ratio is distinguished from the deterioration of the catalyst through the outputs of the air-fuel ratio sensors on the upstream and downstream sides of the catalyst. CONSTITUTION:The locus length LVOM of the output VOM of a O2 sensor on an upstream side, an area AVOM surrounded by VOM and reference voltage, the locus length LVOS of the output VOS of the O2 sensor on a downstream side, and an area AVOS surrounded by VOS and the reference voltage are obtained, and the deterioration of a catalyst is distinguished using the values of a locus length ratio LVOS/LVOM and of an area ratio AVOS/AVOM.</p> |
