Diagram of knock sensor on 1996 mercury villager?

The knock sensor is in the engine V under the intake manifolds and coolant crossover pipe. As it requires considerable disassembly and an expensive new gasket set to reach it, I suggest you make very sure there is something wrong with it first. You will have to remove the upper and lower intake manifolds and coolant crossover pipe assembly to reach it. Just because you are receiving a trouble code for it does not mean there is anything wrong with it. This sensor shares a circuit with other components that often will set a "ghost" trouble code.