A control valve for a fluid flow circuit comprises a body that has a fluid inlet and at least two fluid outlets (20, 22, 24) and that defines an axisymmetric housing for a modulating member capable of rotating about an axis of rotation (XX) and adopting different angular positions to control the distribution of the fluid through the outlets. The body comprises a side wall (16) into which the fluid outlets open. The side wall (16) and/or the modulating member comprises sunken areas (EV) and non-sunken areas (CR), the sunken areas (EV) serving to reduce the surface area of the modulating member (26) in contact with the side wall (16).