Oxidation catalyst with variable activity

The method for the operating of an exhaust gas cleaning system with a particle filter (4) for the separating of soot from the exhaust gas of a self-igniting internal combustion engine (1) entails the continuous or discontinuous oxidizing of the soot by the use of nitrogen dioxide produced by an oxidation catalyser (3) upstream of the particle filter. The oxidation of the nitrogen monoxide contained in the exhaust gas into nitrogen dioxide is a controlled process, whereby the oxidation may be controlled by the adjustable bypassing of the oxidation catalyser or by the influence of carbon monoxide emission of the engine. An independent claim is included for an exhaust gas cleaning system operated by the aforesaid method.