Verfahren zur Überwachung der Funktion eines Systems zur Abgasnachbehandlung

摘要

In the process, the exact nitrogen concentration is compared with predetermined first, second and control values in the exha gas and an error value is produced depending on the comparison results. Controlling a system for after treatment of waste gas involves using an oxidation catalyst (12) arranged with temperature setting device (13;14) with which the exact before and/or after the oxidation catalyst (12) is determined. The exact temperature is comp with a predetermined reference value and all exact temperature values which exceeds the predetermined reference value are added together and this sum is compared with a predetermined exceeded limit value. An error value is obtained. When the sum of the lim value is exceeded to an oxidation catalyst (12) in series in exhaust gas pipe with reduction catalyst (20), where a reduction ag dosing unit is arranged between the oxidation catalyst and the reduction catalyst, then a defined amount of reduction agent is a to the exhaust gas; and after the reduction catalyst (20) arranged in the exhaust gas sensor (33) for obtaining the exact nitrog oxide concentration in the exhaust gas.