Verfahren und Vorrichtung zur Diagnose eines Katalysators im Abgasstrom einer Brennkraftmaschine

摘要

The method involves detecting a threshold value defined lean or fat exhaust mixture composition in an alternative control operation. Fat or lean operation is allowed in alternative control operation after detection of the composition and a time measurement is started. A further fat or lean operation is allowed after the detection, and the time measurement is ended. A time period between the starting and ending of the time measurement is evaluated as diagnosis time for determining an aging condition of the catalyst. An independent claim is also included for a device for diagnosing a catalyst in exhaust gas stream of an internal combustion engine.