Pneumatic control valve of a vehicle air brake system, having at least one first valve system which is arranged in a housing upper part with a first valve piston which can be actuated via an elastomer spring element, and having a second valve system which is arranged in a housing lower part with a coaxially arranged second valve piston which can be actuated by the first valve system and with a second annular plate valve. The elastomer spring element and the first valve piston are configured in one piece as a composite component. In the region of a radial sealing lip of the spring element, the material of the elastomer spring element engages radially and axially in a positively locking manner around a radially outer section of the first valve piston.