A method for heating an exhaust gas catalyst of an internal combustion engine to an operating temperature during a warmup phase includes establishing an enriched mixture as a function of an engine operating state, with a control system. A sensor signal corresponding to a rich or lean mixture is output from a lambda sensor in an exhaust gas system. A quantity of secondary air is blown downstream of outlet valves and upstream of the lambda sensor in the exhaust gas system, from a secondary air pump. A feed quantity of the secondary air pump is pilot-controlled to a stoichiometric exhaust gas ratio, as a function of engine operating parameters, with the control system. The pilot control is corrected with a superimposed closed-loop control in accordance with the sensor signal, starting with operational readiness of the lambda sensor.