I have a 2004 f250 with the 6.0. I just put a sinister egr cooler and replaced the egr valve. Among a bunch of other stuff. The issue I'm having is it is still turning on the check engine light with the po401 code. Which is insufficient egr flow. It is not on all the time usually turns on when pulling a grade or something like that then will go off. Usually turns on when under a load. I have also checked for intake leaks. And didn't find any. Just looking for any other ideas what to check. Thanks.
I replaced the oil cooler when I was in there also along with ipr and other stuff. Pretty much did all the updates to make it bullet proof. Now I get that stupid code when it is under a load pulling a hill or something like that. When I pull a load my trailer or boat I put it in tow mode and the light never comes on. It's like at low rpm under a load.