Abstract: A method and an arrangement for operating internal combustion engines is suggested which is operated in at least one operating state with a lean air/fuel mixture. The fuel mass, which is to be injected, or the injection time, which is to be outputted, is determined in dependence upon a desired value. For monitoring the operability, the actual torque of the engine is determined on the basis of the fuel mass, which is to be injected, or the injection time, which is to be outputted, or the outputted injection time and compared to a maximum permissible torque and a fault reaction is initiated when the actual torque exceeds the maximum permissible torque. Parallel to the above, a quantity, which represents the oxygen concentration in the exhaust gas, is compared to at least one pregiven limit value and a fault reaction is initiated when this quantity exceeds the limit value.