1998 GMC Sierra 1500 4x4 Automatic, 5.7 ltr V8
Ok I really do like my truck but am ready to just burn it to the ground
Put NEW EGR Valve on and now getting P0404 Code
EGR Valve was replaced cause it actually was bad
O2 Sensors were bad have replaced all of them and that fixed the code for the O2 Sensors, but now this, and its driving me crazy, can some one please help me

 

Usually this code points to either carbon buildup or a bad EGR valve. However that doesn't rule out the following:

• Open or short in the 5 Volt reference circuit
• Open or short in the ground circuit
• Open or short in the PCM controlled voltage circuit
• Bad PCM (less likely)

sounds like carbon build up to me

 

Disconnect it and check for a 5 volt reference to the source.

 

Thank you for the replies, ok today I checked all the wiring for the correct voltage stuff found a nice write up on step by step procedures all that checked out, after that I had heard from someone else about running sea foam through the brake vacuum line to clean out carbon so I did that, lol truck smoked like a frieght train for a while. cleared the code again with my scanner, and never fails 20-30 minutes of driving code comes back again , could it be possible the new egr valve is bad? I took it off pintle moves freely up and down could bad catalytic converters cause this code as well? Someone said something to me about a TSB Bulliton about the dealership re-programming the PCM for faulty EGR codes, could this be possible....Once I clear the code and start to drive it truck runs grat but I can feel a hesitation when you first start off from a dead stop when the check engine light is on . I have also noticed when going down the highway say 70 mph and I let off the gas it feels like something is pulling the truck back , almost like a dang jake brake on a big rig but not that bad any ideas guys? thanks