Hi there, thanks for the question.
this is a fuel pressure regulator issue.
although the P0090 can be the result of more than the regulator itself.
generally when it causes a no start situation the flow valve has failed.
this is the regulator at the pump that controls fuel volume via an electric pintle.
it's best to have this replaced at a shop with proper software because it will be calibrated when installed.
best regards, jake
Sorry, is it possible to tell me where I can locate the regulator, or a diagram or the part number please.
Thanks for your answer, I am looking forward to your reply.
It's silver and black coming of the high pressure pump, hard to miss when looking at the pump. Has a 90dgree connector coming off it.