Patent attributes
A method, a device and a computer program product for the diagnosis of an oxidation catalyst for the oxidation of NO into NO2 in a motor vehicle is provided. An exhaust gas aftertreatment system includes at least the aforementioned oxidation catalyst and a particulate filter and/or an NOx-reducing catalyst arranged downstream of the oxidation catalyst, and a predetermined quantity of a reducing agent is supplied to the exhaust system upstream of the oxidation catalyst, and the NOx content or NO2 content is measured downstream of the oxidation catalyst. The method includes measuring a first value for the NOx/NO2 content at a point in time before the reduction agent is supplied to the exhaust gas system, measuring a second value for the NOx/NO2 content at a point in time during the period when the reduction agent is supplied to the exhaust gas system, and comparing the aforementioned values, in conjunction with which an indication of the impaired function of the oxidation catalyst is obtained when the difference between the aforementioned measured values is less than a predetermined first value.
