| 摘要 |
PROBLEM TO BE SOLVED: To possibly execute failure determination in a failure detection device for an exhaust emission control device in which a catalyst unit including an electronically heated catalyst(EHC) is arranged on an exhaust passage of an engine, an air pump is arranged on the exhaust passage for supplying secondary air, current is carried to the EHC and the air pump during cold starting, even when the current carrying is early stopped due to operation starting immediately after starting-up. SOLUTION: After starting current carrying, IAP(pump current) is increased to a peak point. It takes time to stabilize IAP. On the other hand, IEHC(heater current) is speedily stabilized. Waiting time Ytm2A from the starting of current carrying to the starting of detecting IEHC is set shorter than waiting time Ytm2B to the starting of detecting IAP. By advancing the detection starting timing of IEHC, specified detecting time can be secured until the stopping of current carrying to EHC(electronically heated catalyst) even when the stopping timing is advanced due to starting of operation immediately after starting-up. Frequency of malfunction in failure determination of the EHC is reduced. |
