Reading ICP pressure can be tricky on a 6.0L Powerstroke without an analog gauge on the high pressure oil port.

Different programming can skew the ICP function and alter the pressure

value in the pressure data read from the OBD Port. The reason for the

changes it to work around the factory limitations to hold pressure and

keep it throughout the RPM.  Efficiency and response are the two main

factor in the changes.    A good way around this is to read ICP Voltage

and convert  to a pressure value.

Early model ICP sensor.

y=846.24*x-181.66

where

y = pressure

x = volts

Late Model ICP sensor.

y = 22.304x2 + 686.61x + 54.307

where

y = pressure

x = volts

This table will get you close, without doing the calculations.