Abstract: The control valve of the invention has two inlets and one outlet, where a first inlet and the outlet are provided at the front side and the second inlet at the circumference of the control valve. The inlets end in a valve chamber having a fluid connection to the outlet via a valve seat opening. The valve seat opening has a valve seat that can be closed with a valve body that is moveably arranged in a control valve. The outlet extends into the valve chamber with a valve seat section. A radial gap is provided between the valve seat section and a peripheral wall of the valve chamber. The control valve is suitable to be retrofitted to a reservoir pan in order to secure the fuel supply of a single-stage delivery assembly in each operational state when a two-stage delivery assembly is replaced by a single-stage delivery assembly. The control valve comprises a separate valve housing, which is designed such that it can be inserted and fastened in a cylindrical opening.