CONTROLLER FOR INTERNAL COMBUSTION ENGINE

A controller for an internal combustion engine is provided. Control circuitry executes a determination process when the internal combustion engine is in an idling operation state. A pressure sensor detects a passage fuel pressure that is a pressure of gaseous fuel in a portion of a fuel passage between a shut-off valve and a fuel injection valve. The determination process determines whether the shut-off valve is stuck open based on an output of a valve closing signal to the shut-off valve and 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.