A method for venting a fuel tank system of an internal combustion engine is provided, wherein the fuel tank system includes at least a fuel tank, a fuel vapor filter that is fluidically connected to an opening to the environment, a vent line that leads from the fuel tank to the fuel vapor filter, a purge gas line that leads from the fuel vapor filter to a fresh gas tract of the internal combustion engine, a purge gas conveying device that is integrated into the purge gas line, and an exhaust tract with a lambda sensor integrated therein. Control of the purge gas conveying device is carried out based on the measuring signal of the lambda sensor in order to regulate a volume flow of the purge gas in the purge gas line. The method may advantageously be carried out in an internal combustion engine that additionally includes a lambda controller. Since such an internal combustion engine should include a lambda sensor anyway for operating such a lambda controller, the method allows regulation of the venting of the fuel tank system of the internal combustion engine without an additional sensor system, which is advantageous for the manufacturing costs for such an internal combustion engine.