TD4 EML light and error code?

OK the other halfs td4 would not start, narrowed it down to the regulator on back of high pressure injection pump. Changed seals and started fine ran OK but now when car is up to temp it goes into limp home mode and eml is on. Error code is "4496 rail pressure monitoring deviation" Could the regulator be faulty or worn? It has had a new delivery pump and filter? Also swapped rail pressure regulator as had one lying around but same code, Any help appreciated.

If it's coming up with fuel sensor monitoring deviation. It sounds like it could be the fuel pressure sensor to me but I'm not a TD4 expert.

Just a thought could throttle position sensor have anything to do with it, on one occasion the TC light and hill decent light came on with the eml light?