Just finished the Yukon Duramax project and installed a 6-gun. It won't work. I keep getting a 4,1 code. Banks said either a fuel filter or some pins in the harness are pushed out. I changed the filter and checked the harness. There were 2 pins pushed in, I fixed that too. But I still get the same code. Every time I turn the truck off it resets the 6-gun and every time I get on the throttle hard it sets off the code. Has anyone had this code before, what do I do about it? Oh yea banks says to ring out the wires to look for breaks, will do that tonight.

Looks like it is running right, I have low fuel pressure and the 6-gun doesn't like it. Now I need to find the cause of the low fuel rail pressure, 8,000psi when it calls for 23,000psi.

You needa most likily get a fuel preesure regulator my cousin had same prob i replaced it at my shop and works great

Looks like it is running right, I have low fuel pressure and the 6-gun doesn't like it. Now I need to find the cause of the low fuel rail pressure, 8,000psi when it calls for 23,000psi.

You'll get the low fuel rail pressure code when you dry the rails. You need more fuel than your system can deliver. Look into lift pumps. You need them when you start to aproach the 500hp line. I set that code often because i'm running a 500+ tune and always like to get on it. I drain the rails and set the code... especially when i'm trying to smoke out the turnpike ):h

I went ahead and replaced the whole CP3, got one off of ebay for $350. New with FPR. Fixed the problem. 6-gun works great.