Control valve for a fuel injector

Control valve (30) for a fuel injector (100), which is arranged in an injector body (50), with a valve sleeve (1) arranged in the control valve (30), which is guided axially in a movable manner on a guide pin (2) within a guide region (15), in which a guide surface of the valve sleeve (11) and a guide surface of the guide pin (12) interact. The guide surface of the valve sleeve (11) has an undercut (20).