FUEL CELL SYSTEM

A fuel cell system may include a fuel cell; a hydrogen gas supply passage configured to supply hydrogen gas to the fuel cell; a solenoid valve configured to change an opening degree of the hydrogen gas supply passage; a pressure sensor configured to detect a pressure in a downstream supply passage which is a part of the hydrogen gas supply passage from the solenoid valve to the fuel cell; and a control circuit configured to control the solenoid valve. The control circuit may be configured to perform: detecting and storing a conducted electric current conducted in the solenoid valve and the pressure at plural points while changing the conducted electric current at a first sweep speed; and detecting and storing the conducted electric current and the pressure at plural points while changing the conducted electric current at a second sweep speed different from the first speed.