| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a diagnostic device for a NOx sensor having high diagnosis accuracy with securing a stable diagnosis condition without receiving influence of operation of an internal combustion engine. <P>SOLUTION: A diagnosis part constructing a control part 17 diagnoses the NOx sensor 36 after a sufficient period passes from stop of an engine system 10 and an exhaust system 16 is sufficiently cooled. The diagnosis part diagnoses the NOx sensor 36 if outside air temperature detected by an outside air temperature sensor 13 and temperature in an exhaust passage 27 detected by a temperature sensor 35 get almost same. When temperature in the exhaust passage 27 and the outside air temperature are almost same, the engine system 10 is sufficiently cooled, and temperature of the NOx sensor 36 and the exhaust system 16 get into stable states. Consequently, influence of the operation conditions of the engine system 10 and residual heat existing in the exhaust system 16 are eliminated, for diagnosis of heating performance of a heater of the NOx sensor 36. <P>COPYRIGHT: (C)2009,JPO&INPIT |
