| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To reliably detect a trouble of water solution such as reducing agent stored in a storage tank while eliminating the influences of disturbance on the detection of concentration using a temperature sensitive concentration sensor. <P>SOLUTION: This engine exhaust emission control device comprises the concentration sensor 74 consisting of a temperature sensitive element having such a nature that an electric property value is changed with a temperature, and a heater thermally connected to the temperature sensitive element. The temperature sensitive concentration sensor 74 drives the heater and outputs the electric property value for the temperature sensitive element heated by the heater, as a concentration D of reducing agent or precursor. Whether the engine is stopped or not is determined, and a trouble of the stored water solution is detected in accordance with the concentration D detected by the concentration sensor 74 when that the engine is stopped is determined, if it is in another region than a normal region defined with a predetermined value Dslh as a boundary (S407). <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
