MArtin

You need to give a lot more detail to get the help you need (see read before posting at top of forum)
It sounds a poor fault description, but I would say it relates to a 3 rd piston cut off solonoid / circuit on the high pressure pump.
oddly I can't see that on the wiring diagram, what EDC system number is this?
You will need to check wiring back to ECU, these suffer from corroded pins on the ECU.

cheers Aidan