High Pressure Regulator

I would like to know the location of high fuel pressure regulator in my 2001 nissan cedric vq25dd engine. I am just confusing with the fuel pump which installs in the fuel tank. I don't know exactly that the high pressure regulator is attached in engine or in fuel tank. If possible, I would like to get the drawing or picture of high pressure regulator.
Last week, when my mechanic checked the engine, it had got an error code (P1232). When i checked the description of error code in online, i found out that it is the failure of high pressure regulator.

Eagerly looking forward your soonest reply...

Thanks in advance...