| 摘要 |
PROBLEM TO BE SOLVED: To early activate an air-fuel ratio sensor at engine automatic starting while reducing the heater power consumption of the air fuel ratio sensor during an engine is automatically stopped. SOLUTION: When an automatic stop condition is satisfied during the engine is in operation, it is determined that an engine stop request is present, and then the engine is automatically stopped. Together with this, the target element temperature of the air-fuel ratio sensor is switched to a target preheating temperature Tb which is lower than a target activation temperature Ta and a heater current is reduced so that the element temperature T of the air-fuel ratio sensor decreases to be near the target preheating temperature Tb during the engine is automatically stopped. Then, it is determined that an engine start request is present when an automatic start condition is satisfied during the engine is automatically stopped. However, before the engine is automatically started, the target element temperature of the air-fuel ratio sensor is switched to the target activation temperature Ta to increase the heater current so as to quickly increase the element temperature T of the air-fuel ratio sensor to be the target activation temperature Ta, and the engine is automatically started after the element temperature T of the air-fuel ratio sensor reaches the target activation temperature Ta.
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