| 摘要 |
<P>PROBLEM TO BE SOLVED: To diagnose a failure of a NOX sensor. <P>SOLUTION: In this NOX sensor 1, oxygen is discharged by an oxygen pump cell from exhaust gas reaching the NOX sensor, to thereby lower the oxygen concentration in the exhaust gas up to a prescribed concentration, and thereafter NOX in the exhaust gas is decomposed by an oxygen generation cell, to thereby newly generate oxygen, and thereafter the oxygen concentration in the exhaust gas is detected by an oxygen concentration detection cell, to thereby detect the NOX concentration in the exhaust gas. The oxygen pump cell discharges oxygen of the quantity corresponding to a voltage applied thereto from the exhaust gas, and outputs an output value corresponding to the quantity of discharged oxygen. When the oxygen concentration in the exhaust gas reaching the NOX sensor is known, a specific voltage is applied to the oxygen pump cell. When an output value outputted from the oxygen pump call at that time is shifted from an expected value when the oxygen pump cell is normal, the NOX sensor is diagnosed to be in failure. <P>COPYRIGHT: (C)2003,JPO |
