Patent ID: 8087290

Claim:
A method of performing a diagnosis of an exhaust gas sensor disposed in an exhaust gas region of an internal combustion engine, the method comprising: monitoring operating parameters of the engine and operating parameters of the exhaust gas during a running operation of the engine without a controlled intervention of the running operation, wherein the operating parameters of the exhaust gas include one of an exhaust gas mass flow, a NOx concentration and a NOx mass flow; determining during the running operation of the engine whether at least one of the monitored operating parameters of the engine and/or at least one of the monitored operating parameters of the exhaust gas changes in a specified range to verify a suitable engine operating condition for performing the diagnosis; and only upon verification of a suitable change of the engine operating condition or a suitable change of the at least one operating parameter of the exhaust gas for performing the diagnosis, enabling and evaluating a sensor signal of the exhaust gas sensor to determine whether a corresponding change in at least one exhaust gas component that is detectable by said sensor results in an expected change of the sensor signal.