| 摘要 |
PROBLEM TO BE SOLVED: To prevent an inaccurate diagnosis accompanied by temporary increased or decreased catalyst temperature and output an accurate result of diagnosis at a catalyst diagnostic system for diagnosing a deteriorated state of catalyst for purifying exhaust gas of an internal combustion engine.SOLUTION: A control device (37) executes a diagnosis control for catalyst (35) under a condition in which a temperature of the catalyst is kept within an active temperature region. A condition for executing the diagnosis control of the catalyst (35) is set in such a way that a predetermined time elapses from a time in which a temperature of the catalyst (35) approaches a value near a set temperature set in an active temperature region. The predetermined time is set longer as a deviation between a temperature of the catalyst (35) and the set temperature is larger. |
