| 摘要 |
The present invention causes: an ECU 40 to execute a step for causing, after supply of urea water from an urea water spraying valve 33 to an SCR catalyst 34 is stopped, an engine 10 to undergo high-temperature exhaust driving D1, and a step for causing, after reduction of the flow rate of exhaust gas from a cylinder-inside 13 is stopped, the engine 10 to undergo high-flow-rate exhaust driving D2; and a vehicle external computer 52 to execute a step for determining deterioration or malfunction of an upstream NOx sensor 47 and a downstream NOx sensor 48 on the basis of sensed values Ca and Cb acquired when the engine speed Na becomes equal to a determination speed Nx. |
