Abstract: A fuel cell system for a vehicle includes a cooling circuit with a fuel cell assembly and at least one cooler which is fluidically connected to the fuel cell assembly, a data ascertaining device which is designed to ascertain first data that represents a first cooling power of the cooler, and a controller. The first cooling power is an actual cooling power, wherein the controller is designed to obtain the first data, ascertain second data on the basis of the first data, determine a maximally permissible electric output of the fuel cell assembly on the basis of the second data, and control the electric output to be produced by the fuel cell assembly such that the electric output is at least temporarily at most as high as the maximally permissible electric output. The second data represents a second cooling power of the cooler at a specified maximally permissible temperature of a coolant designed to circulate in the cooling circuit. A vehicle, a method, and a computer program are also described.