| 摘要 |
<p>PROBLEM TO BE SOLVED: To avoid wrong diagnosis depending on fuel property and minimize degradation of exhaust gas of an internal combustion engine by compensating self-diagnosis result of exhaust gas related components, suspending self-diagnosis, or canceling the self-diagnosis result, according to state of fuel property. SOLUTION: Catalyst 16 for purifying exhaust gas and air-fuel ratio sensors 9, 10 are arranged in an exhaust gas passage 15. In correction of self-diagnosis based on fuel property judgment result, an operation state adequate to the diagnosis is judged. Then, the fuel property judgment result is checked, and when the fuel property is heavy oil, corrective value of O2 sensor output response delay is multiplied, and performance degradation judgment of the O2 sensor output response is performed. When the fuel property is not heavy oil, performance degradation is judged without correction. In addition, prohibition of self-diagnosis, correction of catalyst performance self-diagnosis, and change of self-diagnosis region can be respectively judged and processed. Thus, degradation of the exhaust gas can be minimized.</p> |
