FUEL CELL SYSTEM

The invention relates to a fuel cell system () with at least one fuel cell stack (), which comprises an anode chamber () and a cathode chamber (), with at least one air conveying device () for the supply of the cathode chamber () with air via a feed air line (), with an outlet air line () from the cathode chamber (), with at least one fuel supply device () for the supply of the anode chamber () with fuel, with at least one anode circuit () for the recirculation of unused fuel around the anode chamber (), furthermore with a cathode bypass (). The fuel cell system according to the invention is characterized in that the cathode bypass line () branches off from the feed air line () upstream of or in the region of a valve device () in said feed air line (), and opens into the outlet air line downstream of or in the region of a further valve device () in said outlet air line (), wherein a gas jet pump () which can be driven by the air which flows around the cathode chamber () is arranged in the cathode bypass (), which gas jet pump () is connected switchably on the suction side to the anode chamber () and/or the cathode chamber ().