| 摘要 |
PROBLEM TO BE SOLVED: To reduce exhaust emission by preventing a sensor element from being damaged by contact with water at the time of a low-temperature start and by executing air-fuel ratio feedback control at an earlier stage. SOLUTION: First, at a low-temperature start (S1), a heater of a downstream air-fuel ratio sensor is energized and first air-fuel ratio feedback control is executed (S2 to S6) based on an output of the downstream air-fuel ratio sensor, then, a heater of an upstream air-fuel ratio sensor is energized to switch the first air-fuel ratio feedback control to second air-fuel ratio feedback control (S2, S7 to S9) based on the output of the upstream air-fuel ratio sensor. COPYRIGHT: (C)2009,JPO&INPIT
|
