Volkswagen Ag

Maciej Kulaszewski

Burkhard Veldten

The invention relates to a method and to a motor vehicle for diagnosing an exhaust gas catalytic converter (), which is arranged in an exhaust gas tract () of an internal combustion engine () and is suitable for converting at least one exhaust gas component, wherein the exhaust gas tract () has an exhaust gas sensor () arranged upstream of the exhaust gas catalytic converter () and has an exhaust gas recirculation system (), which is designed to remove at least part of the exhaust gas from an exhaust gas duct () of the exhaust gas tract () downstream of the exhaust gas catalytic converter () and to feed the removed exhaust gas to the internal combustion engine (). The method comprises the following steps: measuring a first concentration (NOX) of the exhaust gas component upstream of the exhaust gas catalytic converter () by means of the exhaust gas sensor () during fueled operation of the internal combustion engine (), recirculating at least part of the exhaust gas by means of the exhaust gas recirculation system () during unfueled overrun of the internal combustion engine (), measuring a second concentration (NOX) of the exhaust gas component by means of the exhaust gas sensor () during the unfueled overrun of the internal combustion engine (), and determining a state of the exhaust gas catalytic converter () in dependence on the first and second concentrations (NOX, NOX) of the exhaust gas component.

Method for diagnosing an exhaust gas catalytic converter, and motor vehicle

A method for diagnosing an exhaust-gas catalytic converter () arranged in an exhaust-gas system () of an internal combustion engine () for the catalytic conversion of at least one exhaust-gas component from the internal combustion engine (), which has an exhaust-gas recirculation means with which a partial stream of the exhaust gas can be drawn off downstream of the catalytic converter () and fed into the combustion air of the internal combustion engine (), involves determining the current raw emission (NOraw) of the internal combustion engine () in of the exhaust-gas component; measuring the current concentration of the exhaust-gas component (NOmeas) in the exhaust gas upstream of the catalytic converter (); and determining a diagnostic value for the catalytic converter () in terms of the conversion of the exhaust-gas component as a function of the modelled raw emission (NOraw) from the internal combustion engine () and the measured concentration of the exhaust-gas component (NOmeas). The invention further relates to a diagnostic device configured to perform the method and a motor vehicle having such a device.

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Braunschweig, Germany

Maciej Kulaszewski