| 摘要 |
PROBLEM TO BE SOLVED: To always determine whether liquid reducing agent is empty, wrong water solution or regular one by using a sensor outputting signal relating concentration of liquid reducing agent from temperature transfer characteristics between separated two points. SOLUTION: When measurement trigger output every predetermined time after start of an engine is detected, a sensor is driven to measure concentration of urea water solution and counts number of empty determination on which concentration is an upper limit threshold or greater for continuous empty determination or wrong water solution determination on which concentration is a lower limit threshold or less for wrong water solution determination. If number of empty determination or wrong water solution determination is a predetermined value of greater, it is determined that urea water solution is empty or wrong water solution (S42-S45). If number of empty determination or wrong water solution determination is less than the predetermined value, it is determined that urea water solution is regular one (S46). COPYRIGHT: (C)2006,JPO&NCIPI
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