Caterpillar C3.4B high pressure rail

Dear colleagues:
I have a problem with the C3.4B engine, fault code 5571-16, high pressure common rail, damaged pressure sensor was found, it was replaced but the problem still continues.
Rail pressure prv valve changed. new
The actuator of the high pressure pump was changed.used
Rail prv valve open count reset to 0.
Low pressure supply pressure Ok. 65PSI
Injector return line checked. okay
A high pressure test of the pump is carried out, it reaches 150000kpa and the valve does not open, in operation the valve opens (registered in et 96000 kpa) and causes the code. Sometimes the valve opens when the engine starts.
The ecu of another machine is replaced, the failure continues.

How many times had the prv opened and how long was the duration of the opening? I'm not sure what your code means, but I assume that it is for low rail pressure. If your prv has opened more than 50 times and for long periods of time. A groove could have been cut into the rail from the high pressure being released. If that's the case then you need to look into what regulates the fuel flow and replace the common rail. Otherwise you will have to isolate and measure all of your fuel returns to see what is failing. Just a friendly reminder. Please be careful when opening connections on the high pressure side of the system.

Ohm and load check the wires between the pump actuator and the ECU. Can't say for sure on that Cat engine, but typically when there is open circuit to the pump actuator it defaults to full open. With max pump flow the rail the pressure will reach the opening pressure of the relief valve. Also that code can be generated by unplugging the actuator while the engine is running on a operational engine.