Verfahren zur Diagnose eines Schädigungszustandes eines in einem Abgaskanal einer Verbrennungskraftmaschine angeordneten NOx-Speicherkatalysators

摘要

The invention relates to a method for diagnosing the level of deterioration of an NOx catalyst located in the exhaust channel of an internal combustion engine. The NOx concentration in the exhaust gas is detected by an NOx sensor disposed downstream of the NOx storage catalyst. The internal combustion engine is provided with a device for adjusting a minimum operating temperature of the NOx storage catalyst which device at least temporarily influences the exhaust gas temperature (heating measure). According to the inventive method (a) a signal course (16) of the NOx concentration is detected by the NOx sensor within a predetermined diagnostic period once the heating measure (consisting of measures on the motor side and blowing in of secondary air) is terminated, and (b) the signal course (16) of the NOx concentration is compared with a predetermined nominal course (14) for the NOx concentration.