| 摘要 |
<P>PROBLEM TO BE SOLVED: To determine whether abnormal conditions occur in a NOx sensor. <P>SOLUTION: When the output value of the NOx sensor for measuring NOx concentration in an exhaust gas is less than a predetermined threshold (S7), if a NOx integrated quantity estimated from an engine state is greater than a first predetermined value (S8), a vehicle travel distance is greater than a second predetermined value (S9), or fuel consumption is greater than a third predetermined value (S10), it is determined that the abnormal conditions occur in the NOx sensor and thus an alarm unit is operated (S11). Namely, if the NOx sensor is normal, it is very rarely that the output value continuously becomes less than the predetermined threshold in a prescribed period. Meanwhile, if the abnormal conditions occur in the NOx sensor, the output value continuously becomes less than the predetermined threshold in a prescribed period. By using the characteristics, it is determined whether the abnormal conditions occur in the NOx sensor. <P>COPYRIGHT: (C)2010,JPO&INPIT |
