ive been throwing code p0401 and p0402 for some time now. ive done much searching in the forums, and can't seem to figure out the issue. i've replaced the DPFE and EGR, and still have "insufficient EGR flow."

from a recommendation here on RF, i put some cheapo engine cleaner in the fuel tank, and it actually fixed the problem. however, that doesn't work anymore, and my truck won't pass inspection until i can fix it.

im guessing the lines are plugged up with carbon, and i think the next step is to clean the hoses, but im not sure which ones.

if someone can point me in the right direction for cleaning out the hoses, or offer a better suggestion, that would be great, thanks!

 

it also nearly stalls out when shifting from drive to park (automatic), if that's any indication of anything

 

so its really bad now. truck came damn close to stalling out this afternoon while parking. anyone have any insight?

 

My truck is throwing the same codes... im probably going to end up having to replace the same two things you did, and see where that goes. My buddy threw his 8000 dollar computer (he sells tools for snap on) on it and came up with a whole list of possibilities as to why its doing it... it could be something as simple as a vacumm leak to the EGR valve or the sensor, i'll have him look up what it is in the computer again and let me know. When i find out i'll list them on here if you dont' have any answers/possiblities yet.

-Brad

 

Yeah you have a clog somewhere in the EGR system. You need to check the lines for carbon build up.

EDIT: Sometimes when you replace the EGR valve you end up knocking some carbon loose that can clog up the next valve. Try letting the engine run without the EGR valve on it for a few seconds. Check all your vacuum lines and EGR ports.

 

has this thread been updated at all. I had a question about cleaning the vacuum lines. I have p0401 and i already cleaned a crap load of carbon out of it. still have the code. When i disconnect the vacuum line while the truck is running i get little suction. I think it may be clogged. how the hell eo i clean this thin tube? my truck also stalls when in nuetral at stop signs.