There is a small part mounted behind the valve cover, it looks like a big nut with a large bolt-type thing threaded into it. A single black wire protrudes from one end. It is mounted using one of the vale-cover nuts.
I have been totally unable to work out what this is working from the Bentley manual and from teh wiring dagrams. My first thought was a knock sensor but the diagram shows that that has *three* wires. Does anyone know what this thing is and ideally where it fits in the wiring diagram?
Thanks
Rich