Abstract: A wastegate actuator control valve for a wastegate of a turbocharger of an internal combustion engine is disposed in the intake manifold pressure supply line to the wastegate actuator and has a spring-biassed piston preventing intake manifold pressure from being transmitted through said line until a predetermined intake manifold or boost pressure is reached. The valve housing also has a bleed orifice communicating to the atmosphere to relieve any residual pressure in the actuator when the valve is closed but which bleed orifice is closed upon the piston moving to the open position. Such residual pressure relief results in the full preload of the actuator spring being exerted to completely close the wastegate. Further, the piston is provided with a metering orifice through which the intake manifold pressure flows to the wastegate actuator.