Controller for internal combustion engine

A controller for an internal combustion engine mounted on a vehicle, the internal combustion engine including a fuel tank storing gaseous fuel, a fuel injection valve supplying the fuel into a cylinder, a fuel passage connecting the fuel tank to the fuel injection valve, a shut-off valve disposed in the fuel passage, and a pressure sensor disposed in a portion of the fuel passage between the shut-off valve and the fuel injection valve and configured to detect a passage fuel pressure that is a pressure of the fuel in the portion, the controller comprising processing circuitry, wherein

• the processing circuitry is configured to
• output a valve closing signal to the shut-off valve,
• execute a determination process of determining whether the shut-off valve is stuck open based on a decrease amount of the passage fuel pressure that occurs until an elapsed period after the valve closing signal is output reaches a predetermined specified period, and
• exclude, from the elapsed period, a period in which a fuel cutoff process for stopping fuel injection by the fuel injection valve during operation of the internal combustion engine is executed.