A method for controlling a fill level of an exhaust gas component store of a catalytic converter of an internal combustion engine, in which the fill level is controlled by using a system model, which includes a catalytic converter model, and uncertainties of measurement or model variables, which influence the control of the fill level, being corrected by an adaptation that is based on signals of an exhaust-gas probe situated on the output side of the catalytic converter. The method provides that an adaptation requirement is learned as a function of the operating point, the learned adaptation requirement is stored as a function of the operating point, and a distinction is made based on the operating point dependency between different causes of the uncertainties. Also described is a control unit to carry out the method.