Disclosed is a check valve (5) that is screwed into a threaded bore (1) of a housing (2) of a hydraulic subassembly between a first pressure side (26) and a second pressure side (27) by means of an external thread (11) which is disposed in a first cylinder section (8) of a cylindrical valve housing (6) of the check valve (5). A passage duct (39) which allows a hydraulic fluid to flow between the sidewall of the threaded bore (1) and a first removed portion (16) of the surface area (10) of the cylindrical valve housing (6) is embodied in at least one angular segment (a1, a2, and a3) of the valve housing (6).