| 摘要 |
<P>PROBLEM TO BE SOLVED: To diagnose the deterioration of an NOx sensor without deteriorating exhaust emission. <P>SOLUTION: In this deterioration diagnosing apparatus of the NOx sensor equipped with pump cells 67 and 68 for discharging oxygen of a gas to be detected at the time of application of voltage and sensor cells 75 and 70 for emitting the output I<SB>1</SB>corresponding to the concentration of NOx of the gas to be detected after oxygen is discharged by the pump cells, the deterioration of the NOx sensor is determined on the basis of the output change of the sensor cells at the time when the voltage Vp applied to the pump cells is changed over. Since it is unnecessary to change the combustion state or the like of an internal combustion engine, the deterioration of exhaust emission at the time of diagnosis can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT |
