| 摘要 |
The invention relates to In an operating and diagnostic method for an SCR exhaust gas aftertreatment system which has an SCR catalytic converter with ammonia storage capacity, a signal of an exhaust gas sensor that is sensitive to nitrogen oxide and ammonia and is arranged downstream of the SCR catalytic converter, is measured. In a normal operating mode, ammonia is supplied to the SCR catalytic converter corresponding to a filling level model for ammonia stored in the SCR catalytic converter, in such a way that the ammonia filling level of the SCR catalytic converter is held at least approximately at a predefinable nominal value (or value range). The normal operating mode is interrupted if an exhaust gas sensor signal that exceeds a predefinable first limit value, is registered, and the set urea dosing rate is increased by a predefinable degree in relation to the value provided in the normal operating mode. Thereafter, a return is made to the normal operating mode, or a switch is made to a diagnostic operating mode, as a function of the profile of the signal of the exhaust gas sensor.
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