Hello everyone, I've been a fan for awhile and just registered. Here is what I have: 2007 6.0 CC DRW 4x4 118,000. 4"MBRP Turbo back with no cat. S&b cold air intake. Commuter with about a 60 mile round trip.

Here is the problem: CEL light came on and it seems to be making a lot more "diesel" clacking and less power. Code p0402 ( I had oriely read it and don't know what brand scanner it was)

Back ground: I bought the truck about 2 mo ago from a dealer. 1 owner trade in. All work stated above was already done. I got the service records from the dealer. Head gaskets, oil cooler and EGR cooler all replaced in 2010. I had the truck for a week or so when the CEL came on. Dealer replaced the EGR valve. All good.. Until it came back on. Before I could take it back an injector failed and left me on the side of the road. The dealer replaced the injector and fuel pressure regulator. Light came back on a few days later. Dealer said that either the cold air intake was causing it, because they installed a factory air box and it didn't give the code. Or the previous owner had a block off on the EGR. Cleared the code and it ran like a top for 3 weeks.

To the chase: today the light came on and is running a little rough with lots of "diesel" clacking same code as before p0402.

Any thoughts would be appreciated

 

Your p0402 is high EGR flow. It could be your back pressure sensor. It's kind of all tyed in to your EGR system.

 

So I might assume either the EGR valve is stuck open?? Or the dpfe sensor is bad? The EGR valve has about 1000 miles on it...

I took it out yesterday and ran it pretty hard for about 50 miles. Stopped for about 20 min. When I started it up the light went out and it ran great?!?!?

 

My only real advice for you would just delete the cooler and the EGR valve. Then you will never have that trouble again.
I say that because you seem to have a fair bit of troubles with it.