| 摘要 |
<p>PURPOSE:To prevent the erroneous judgement of the deterioration of a catalyst by prohibiting the catalyst deterioration detection by a catalyst deterioration detecting means when an air-fuel ratio sensor deterioration detecting means detects the deterioration of the first air-fuel ratio sensor. CONSTITUTION:The specific component concentration in exhaust gas is detected by the first and second air-fuel ratio sensors M1 and M2 on the upstream and downstream sides of a catalytic converter CCRO, and an air-fuel ratio adjusting means M3 calculates the air-fuel ratio correction quantity according to the output M1 of the first air-fuel ratio sensor and adjusts the air-fuel ratio of an engine. Further, a catalyst deterioration detecting means M4 judges the deterioration of the catalyst in a catalytic converter according to the output of the second air-fuel ratio sensor M2, when the air-fuel ratio is adjusted. Accordingly, when an air-fuel ratio sensor deterioration detecting means M5 detects the deterioration of the first air-fuel ratio sensor M1, a catalyst deterioration detection prohibiting means M6 prohibits the catalyst deterioration detection by the catalyst deterioration detecting means M4. Accordingly, the erroneous judgement of the deterioration of the catalyst in spite of the fact that the catalyst is normal can be prevented.</p> |
