| 摘要 |
<p>PURPOSE:To precisely detect abnormality of the secondary air supply device and prevent deterioration of operability by displaying that abnormality is recognized in the secondary air supply device if an output of an air-fuel ratio sensor is rich when the secondary air is supplied under a specified operating condition of an internal combustion engine. CONSTITUTION:Specified operating conditions of an internal combustion engine such as idling, decelerating and so on are detected by specified operating condition detecting means A, and only under specified operating conditions, the secondary air is supplied into an intake passage of the internal combustion engine by the secondary air supply device B. The residual oxygen density in exhaust gas is detected by an air-fuel ratio sensor C disposed in an exhaust passage on the downstream side of the secondary air supply device B, and under conditions other than the specified operating conditions, according to an output of the air-fuel ratio sensor C, the air-fuel ratio is F/B controlled by an air-fuel ratio control device D. Under specified operating conditions, it is judged by abnormality detecting means E whether an output of the air-fuel ratio sensor is rich or not, and if it is rich, the abnormal state of the secondary air supply device B is displayed.</p> |
