A method of determining the concentration of a gas component in the exhaust gas of an internal combustion engine

To determine the components of an exhaust gas composition, from an internal combustion motor (1), a gas sensor (5) is downstream of a catalyst (4) in the exhaust gas pipe (3). The sensor is linked to an electronic control unit (7). A second sensor (5) is in the exhaust gas flow, for the control unit to register a gas component from the two sensor signals, and especially the nitrogen oxide content.