| 摘要 |
PURPOSE: To perform proper control in consideration of a moisture content adhered to a sensor and to prevent breakage of a sensor by differing the heater energization starting timings of sensors from each other, in an internal combustion engine having a an air-fuel ratio sensor with a plurality of built-in heaters. CONSTITUTION: First and second air-fuel ratio sensors 118 and 119 with respective built-in heaters situated upper stream and downstream, respectively, from a catalyst converter 117 are arranged in an exhaust passage 115 in which a catalyst converter 117 is located. Simultaneously with the starting of an engine, the first air-fuel ratio sensor 118 is energized and it is decided whether the heater of the second air-fuel ratio sensor 119 is energized. When it is decided that NO heater is energized, it is decided whether an exhaust gas temperature (h) attains the heater energization starting exhaust gas temperature of the second air-fuel ratio sensor 119. In the case of YES, when it is decided that the heater is energized, energization to the second air-fuel ratio sensor 119 is started. As noted above, by starting energization after a lapse of a given time beginning with a starting, element breakage and running-down of a battery are prevented from occurring. |
