| 摘要 |
PURPOSE:To detect the deterioration of a sensor by connecting a resistor having a prescribed resistance value in parallel with a signal line between an oxygen sensor and an A/D converter by a normally opened switch and providing a display device for displaying a reduced input value at the close of the switch and an input value before the reduction respectively. CONSTITUTION:At a normal operation time, a switch means 19 is opened and the output of the oxygen sensor 11 is inputted to a CPU13 through the A/D converter 14. The CPU13 calculates the feeding quantity of fuel and drives an actuator 9 to adjust the feeding quantity of the fuel by a feeding quantity adjusting means 8. In case of the testing of the sensor 11, an operation part 25 is operated, the actuator 9 is set up by the CPU13 so that the system becomes rich with fuel, the control operation of a control part 12 is turned off, and an oxygen detecting signal is displayed on a display device 26. Then, the switch means 19 is closed, and under a condition that a resistor 20 having the same initial internal resistance value as that of the sensor 11 is connected in parallel with the converter 14, a detecting signal is displayed on the display device 26 to decide the deterioration of the sensor 11 from the degree of reduction of the indication. |
