METHOD FOR DETERMINING MALFUNCTION OF NITROGEN OXIDE SENSOR AND SELECTIVE CATALYTIC REDUCTION SYSTEM OPERATING THE SAME

摘要

A nitrogen oxide sensor break-down decision method and a selective reduction catalyst system for implementing the same are provided to determine a trouble whether or not of the nitrogen oxide sensor by deciding increment or the reduction of the sensor signal. A nitrogen oxide sensor break-down decision method performs the followings: a step for comparing amount of the nitrogen oxide detected by the set values and sensor of the nitrogen oxide included in the exhaust gas(S210); a step that whether the engine is the steady- state or not determines if the range within in which the difference of the value found from the set value and sensor of the nitrogen oxide is set up (S230); a step controlling so that it changes the set up condition and the nitrogen oxide increases or the condition reduce if the engine is the steady- state(S250); a step determining whether the signal of sensor increases and the signal reduces or not when nitrogen oxide increases or reduces; and a step determining sensor breaks down in case nitrogen oxide doesn't increase or reduce(S290).