| 摘要 |
A method for correcting a sensed value of a nitrogen oxide sensor according to an embodiment of the present invention includes a step of sensing a first measurement value which is the concentration of a nitrogen oxide via the nitrogen oxide sensor installed in an exhaust line under a preset condition that an engine is off; a step of sensing a second measurement value which is the concentration of a nitrogen oxide included in exhaust gas via the nitrogen oxide sensor in the idle state which the engine is on; a step of setting a deteriorated nitrogen oxide sensor characteristic line based on the first and second measurement values; a step of calculating a drift offset value and a slope offset value between a preset normal nitrogen oxide sensor characteristic line and the deteriorated nitrogen oxide sensor characteristic line; and a step of determining a malfunction of the nitrogen oxide sensor when the drift offset value and the slope offset value are over a preset value. Therefore, the present invention measures the concentration of the nitrogen oxide contained in the air inside the exhaust line under the preset condition that the engine is off and measures the concentration of the nitrogen oxide inside the exhaust line in the idle state of the engine, thereby easily setting the deteriorated nitrogen oxide sensor characteristic line. Additionally, the present invention can easily correct the sensed value by using the drift offset value and the slope offset value between the deteriorated nitrogen oxide sensor characteristic line and the normal nitrogen oxide sensor characteristic line. Furthermore, the present invention can easily determines a malfunction of the sensor by using the calculated drift offset value and the slope offset value. [Reference numerals] (AA) Measurement value; (BB) Drift offset; (CC) Mapping value |
