| 摘要 |
PURPOSE: To provide a device deciding the active state of an air-fuel ratio sensor at a low cost with high precision. CONSTITUTION: From a point of time when an output signal based on a limit current flowing through the element 3a of an air-fuel ratio sensor 3 to indicate a constant value at an initial stage exceeds a predetermined threshold and a fluctuation is started, a difference between the heater resistance value of the heater 3b of the air-fuel ratio sensor 3 and a heater resistance value at a reference temperature is integrated. When an integrating value attains a predetermined decision value, it is decided that the air-fuel ratio sensor 3 reaches a complete active state. |
