Patent attributes
When concentration of reducing agent stored in reducing agent container deviates from predetermined range or when residual amount of reducing agent becomes equal to or smaller than predetermined amount, it is judged that liquid in reducing agent container is different aqueous solution or reducing agent is deficient (abnormal judgment). Upon restarting of engine operation, if abnormal judgment is made and vehicle's travel for a predetermined distance or more occurs after abnormal judgment, restarting of engine operation is inhibited. At this time, if elapsed time until restarting of engine operation is performed from stopping moment of engine operation is less than predetermined time, engine operation is judged to be unintentionally stopped, and restarting of engine operation is permitted enabling a prompt action in emergency. But, even when abnormal judgment is made, if vehicle travels a distance less than predetermined distance after abnormal judgment, restarting of engine operation is permitted enabling vehicle to travel to reducing agent replenishing point.
