| 摘要 |
PROBLEM TO BE SOLVED: To determine normality/abnormality of an exhaust gas temperature raising system and a secondary air introducing system, in a catalyst early warm-up control system which introduces a secondary air into an exhaust pipe while raising temperature of an exhaust gas during catalyst early warm-up control, to generate after burning. SOLUTION: During the catalyst early warm-up control, the temperature of the exhaust gas flowing in a periphery of an air-fuel ratio sensor and in a catalyst is changed depending on the normality/abnormality of the exhaust gas temperature raising system and the secondary air introducing system, and according to this change, a proceeding state of warm-up of the catalyst and a proceeding state of an activation of an air-fuel ratio sensor are changed. When the secondary air introducing system becomes abnormal and a secondary air introducing amount runs short or becomes excess, an air-fuel ratio of the exhaust gas in the periphery of the air-fuel ratio sensor is changed accordingly. By focusing attention on the relationship, the proceeding state of the activation of the air-fuel ratio sensor and an output (air-fuel ratio of the exhaust gas) of the air-fuel ratio sensor are determined, thereby respectively determining the normality/abnormality of the exhaust gas temperature raising system and the normality/abnormality of the secondary air introducing system. |
