6.0 check engine light on going problem

[06f350stroker6589]

I have a 06 f350 6.0 and i have a p0402= egr stuck open. I just got it back from the 2nd dealer in 3 weeks. It just cost me $800 for a new egr valve and a complete engine cleaning . They cleaned my intake turbo and egr cooler. It took 8 hrs on a machine to completly clean. They also put in a baffle to elimanate further egr problems. Well my check engine light just came back on with the same p0402 code. I do have a straight piped exaust with an air intake system. Ive heard that they could trip this code. But ive had this system in for over a year and have not had 1 problem until recently. I paid $2000 for a warranty that my dealer supposely fixes the problem but it never works. So i just brought it to a top diesel ford dealer with 6.0 mechanics and i have the same result. Does anybody know why this check engine light is still on???

[Robsr]

This codes indicates excessive flow detected. could be a number of things causing it. the valve could be stuck open, the valve could be forced open under high load/boost or.... there are pretty specific test' related to this code, should be a slam dunk to fix for any competent tech.

I would say they are NOT doing a thorough test drive if the problem is recurring after delivery.

[06f350stroker6589]

Its my 3rd dealer they said they have checked everything and replaced my egr twice . Then cleaned out my egr cooler turbo and intake. It sat for hrs on the machine cleaning. But ford has a tsbindicating that my checkengine may come on do to my aftermarket exaust and intake. Theirs no o2 sensors and i have never heardof that causing a problem. I have atleast 20 friends that have 6.0s with aftermarket exaust with no issues. This makes me want to buy a cummings