MP8 EGR Code 2791 and wont regen

[Goddy454]

Happy Holidays All. I have a baffling issue here. The truck is throwing a 2791 FMI 5, current below normal or open circuit. I have replaced the valve and the harness is a couple months old, fault was present before changing these items. The truck is calling for a regen also but will not initiate one through the dash switch or through PTT either. I have done the PTT test of checking resistance to the valve directly and passed with 4.1 ohms. Did the second test of connecting valve and checking resistance from ECM connector pin to pin. Checked out with 4.1 ohms too. With these results PTT says fault cant be recreated. As of now that would make me believe ECM but PTT makes no mention of that even being a possibility. Oddly enough when truck is cold and waiting to reach normal temps it started to idle up and do its own regen. I stopped it and then pressed the dash switch and it proceeded to perform a regen. I once again stopped it as the truck was in the garage. Once the truck reached operating temps I attempted to run a regen and couldnt. The switch would not permit me nor would PTT even though all conditions said OK. I attempted the EGR valve test and I could not do that either. The window showing commanded position would flicker a red X and read 95. Anybody give me their take on this. That would be appreciated. Thanks

[Goddy454]

A little update, I was able to clear the EGR fault for a little while and with that erased the truck will do a regen. The regen failure is a definte result of the EGR fault. Let me also add that the EGR valve I put in was an aftermarket as the Mack valve is like 3K. I know a lot of this aftermarket stuff is crap, should I just get a Mack unit?