A method of operating an exhaust system

The invention relates to a method for operating an exhaust system comprising at least one oxidation catalyst and at least one suitable for a selective catalytic reduction arrangement, with at least one measuring probe for determining the effectiveness of the arrangement, which comprises at least the determination of a reaction efficiency of the arrangement with the aid of at least one measuring probe, and comprises the calculation of an efficiency of the nitric oxide reaction in the oxidation catalyst from the determined conversion efficiency. With the help of the inventive method to assess the effectiveness of nitric oxide to nitrogen dioxide reaction can be obtained an oxidation catalyst in the exhaust system without additional probes in or on the oxidation catalyst. This reduces the frequency of maintenance of the exhaust system, while enabling precise control of the total exhaust gas conversion.