An internal combustion engine has an intake duct, at least one cylinder that takes in air via the intake duct and an exhaust gas duct, in which the exhaust gas catalytic converter is located, and into which the combusted air/fuel mixture is ejected from at least one cylinder. Depending on measurement values that are determined by sensors, input signals for the control of actuators of the internal combustion engine are generated by means of control functions based on torsional moment and by means of a dynamic charging model of the intake duct. A measurement is determined, which characterizes the difference of a desired air mass flow into the respective cylinder from an actual air mass flow into the cylinder. Depending on the measurement, a proper or improper heating up of the exhaust gas catalytic converter is identified.