METHOD OF OPERATING FUEL CELL SYSTEM

A fuel cell system includes a fuel cell stack, a fuel gas supply channel, a circulation passage, a purge valve, and a temperature sensor. A method of operating the fuel cell system performs a judging step of determining whether or not the temperature detected by the temperature sensor is at or below a given temperature. Then, if the temperature is at or below the given temperature, the method performs a purge valve scavenging process step of intermittently opening and closing the purge valve multiple times, while supplying the fuel gas through the fuel gas supply channel.