My 4.6L (in a 98 Expy) with 126K miles has the P0401 code. I replaced the DPFE module. Still have code; shiny new module looks great though. Tried to remove EGR valve but have been unable to break the bolts loose, and fear rounding off the heads or twisting the heads off if I get more agressive with them. I've tapped on them, soaked them with WD-40, and even tried breaking them loose with a closed end wrench and a hammer. No luck.

So ... if I remove the part to which the EGR is attached will I have sufficient access to the EGR ports to clean the carbon buildup out of them? Pretty sure that's where the prob is.

 

Nevermind. I saw AggieMike's post, got my tools, and got after it. Ports looked a lot like his. Cleaned it out with a small screwdriver and a piece of coat hanger, vacuumed out all the loose pieces, bolted it back up, and cranked her up. Tested EGR function with hand vacuum pump. Now when I pull a vacuum on the valve at idle the engine starts to stall out as it should; it didn't do this before I cleaned the ports. Thanks AggieMike from one Aggie to another; your picture was worth a thousand words.

BTW Ford wanted $275 to install new EGR valve, and cleaning the ports was gonna be an extra charge on top of that.

AggieMike's post - https://www.ford-trucks.com/forums/s...&highlight=egr