Abstract: A pressure washer gun is connectable to a source of fluid. The pressure washer gun includes a housing that defines an interior and a flow path disposed substantially within the interior. The flow path includes an inlet in fluid communication with the source and an outlet. A valve at least partially defines a portion of the flow path and is movable between a closed position and an open position in which fluid travels from the inlet to the outlet. A user interface is movable between an actuated position in which the valve is open and a non-actuated position in which the valve is closed. A lock member is substantially disposed within the interior and is movable in a substantially arcuate path between a locked position in which the lock assembly inhibits movement of the user interface, and an unlocked position.