| 摘要 |
PURPOSE:To prevent air/fuel ratio becoming excessively rare temporarily by open loop controlling air/fuel ratio to the value set beforehand as soon as the heater, contained in an oxygen sensor, is disconnected. CONSTITUTION:Output (R) of a sensor 10 is raised when a heater 11 of an oxygen sensor is disconnected due to some reason. On the other hand, the electric potential at a connecting point of a heater 11 and a resistor 21 is raised nearly to that of the power supply. As the result, a comparator 26 generates a disconnection detecting signal while an air/fuel ratio control unit 28 is immediately shifted to an open loop control, fixing an air/fuel ratio to the basic point. Furthermore, when disconnection detecting signal is sent from the comparator 26, an indication lamp 27 comes on as an alarm unit. |
