ISX12 fault 0553

[swayte]

to start with the engine is an isx12 esn 75010036 CM2250 demandated in a 2013 pete 365
fault 0553 is active the entire time running the truck. fuel rail pressure currently runs 32,000+/- 1,000 psi at idle. there are no other fault codes present or active. fuel pump actuator test at 2.5 ohm resistance. have installed a clear section of fuel line to check of any air egress. found no air bubbles in fuel. have replace fuel pump actuator with a oem actuator. inspected actuator bore for any defects. no defects present. had the guy that perform the demandate return truck to factory software for test with no change. he stated that it was checked for revision update and was completed at the time. there was no change to fuel rail pressure. had the demandate software reinstalled. have also checked for fuel return line restriction, removed check valve from head drain line and ran fuel into a bucket. have resistance test and load test engine harness to fuel actuator and fuel rail pressure sensor.
parts that have been replace or swapped from know good engine;
6 reman fuel injectors (old were leaking)
fuel rail pressure sensor new oem
fuel rail relief valve (before i was working on it)
fuel pump actuator new oem
complete fuel pump head swapped from another truck
ecm swapped

sorry for the long post but the has been an issue for sometime and can't find any resolution