| 摘要 |
<p>PURPOSE:To improve accuracy of trouble diagnosis of a secondary air introduction device. CONSTITUTION:A trouble diagnostic device is provided with an oxygen sensor 4 for detecting oxygen concentration in exhaust gas while being interposed downstream from the connection part between an exhaust passage and a secondary air introduction passage, a means 1 for judging whether the secondary air is being introduced or not, and a means 2 for diagnosing abnormality of the secondary air introduction device during introduction of the secondary air, based on a detection signal of the oxygen sensor, and a means 3 for stopping abnormality diagnosis of the secondary air introduction device under an operation condition in which at least one of a fuel injection quantity, an increase rate of the fuel injection quantity, and rotational speed increases beyond its standard value.</p> |
