| 摘要 |
PROBLEM TO BE SOLVED: To enable more highly accurate determination of failure of a sensor.SOLUTION: A failure determining device of an NOx sensor is provided on the downstream side of a catalyst having oxidation capacity in an exhaust passage of an internal combustion engine, and detects the NOx concentration in exhaust gas, and includes an estimating means for estimating or detecting the NOx concentration in the exhaust gas on the upstream side of the catalyst, and a determining means for determining that the NOx sensor causes failure when the length of a locus of a detecting value of the NOx sensor in a predetermined period is a threshold value or more and an absolute value of a difference between the detecting value of the NOx sensor and the NOx concentration estimated or detected by the estimating means is the threshold value or more. |
