A method for operating a drive device having an internal combustion engine and an exhaust gas purification device for exhaust gas of the internal combustion engine includes performing an oxygen removal operation for removing oxygen from the exhaust gas purification device, wherein the oxygen removal operation includes at least one of operating the internal combustion engine sub-stoichiometrically and introducing additional fuel into the exhaust gas, wherein the oxygen removal operation is performed until a lambda value detected by a lambda probe arranged in the exhaust gas purification device reaches a defined lambda threshold value.