An internal combustion engine has a tank ventilation system and a crankcase ventilation system. The tank ventilation system is connectable to an intake system downstream of a throttle element via a first non-return valve in a first line and upstream of a compressor via a second non-return valve in a second line and a third non-return valve in a second sub-line. The crankcase ventilation system is connectable to the intake system downstream of the throttle element via a fourth non-return valve in a third line and upstream of the compressor via a fourth line and the third non-return valve. The intake system is connectable to the second line downstream of the throttle element at a transitional point between the second line and the second sub-line via a fifth nonreturn valve in a fifth line. A nozzle is formed at the transitional point from the fifth line to the second line and the second sub-line, and the second line opens into the nozzle downstream of the second non-return valve. A first pressure sensor for measuring the pressure in the second line is provided in the second line between the second non-return valve and the nozzle. Only a single pressure sensor is required to diagnose or detect a leak.