Sneak path elimination in diode multiplexed control of downhole well tools. A system for selectively actuating multiple well tools includes a control device for each tool, a well tool being operable by selecting a respective control device; conductors connected to the control devices, which are selectable by applying a predetermined voltage across a respective predetermined pair of the conductors; and at least one lockout device for each control device, the lockout devices preventing current from flowing through the respective control devices when voltage across the respective predetermined pair of the conductors is less than a predetermined minimum. A method includes selecting a well tools for actuation by applying a predetermined minimum voltage to a set of conductors; and preventing actuation of another well tool when the predetermined minimum voltage is not applied across another set of conductors, at least one conductor being common to the two sets of conductors.