Abstract: A hydrogen sensor includes a communication terminal, a plurality of identification terminals, and an ID setting section. The communication terminal is connected to a first communication bus or a second communication bus, and communicate with a vehicle ECU. Each of the plurality of identification terminals is set to either an open state (OPEN) in which the identification terminal is not connected to any potential or a grounded state (GND) in which the identification terminal is connected to a ground potential. The ID setting section sets an identifier in either a standard format or an extended format, according to a difference in the communication bus to which the communication terminal is connected.

Abstract: A fuel cell system monitoring fuel gas detection results of a gas sensor after outputting a valve-opening command signal to a first on-off valve and outputting a valve-closing command signal to the second on-off valve when an operation of a fuel cell stack is stopped and an oxygen-containing gas stops flowing through oxygen-containing gas supply flow path.

Abstract: A hydrogen sensor includes a communication terminal, a plurality of identification terminals, and an ID setting section. The communication terminal is connected to a first communication bus or a second communication bus, and communicate with a vehicle ECU. Each of the plurality of identification terminals is set to either an open state (OPEN) in which the identification terminal is not connected to any potential or a grounded state (GND) in which the identification terminal is connected to a ground potential. The ID setting section sets an identifier in either a standard format or an extended format, according to a difference in the communication bus to which the communication terminal is connected.