Hey all, to start off, I've researched the heck out of P0401 but I need more advice.... I have an 04' F250 w/a 6.0, 61k miles, completely stock. I have been getting a reoccurring P0401 EGR flow CEL. I've checked all the fittings and tubes and see no cracks or breaks. I've checked the exhaust system and no signs of leaking soot anywhere except on the passenger side exhaust manifold, there is some minor deposits of soot near the first two cyclinders, but that's it. Everything else looks good and I can't hear any hissing either. I am not getting any white smoke from the exhaust. I pulled my EGR valve and looked at it, it looked fine. I cleaned it off and put it back in. Then I got a new one just to see if that fixed it. I am missing a little coolant. I'm adding maybe a few cups of coolant every few weeks. Truck is always serviced and only repairs was Ford replaced the EGR valve in 2008. When I pull my EGR valve, it is slightly moist in the housing but not wet and no sludge. Again, the EGR valve had a nice layer of soot, no build up or sludge on it....

I would hate to take it to Ford because who knows what they will say, but what does everyone think? Thanks everyone....

 

Moisture below the egr valve is not good. It should be totally dry. Also, losing coolant is a sure fire sign combined with the egr, that you are developing a crack in the egr cooler itself, allowing coolant to enter the intake.
Are you seeing any white smoke at cold start up?
If that's indeed the case, that crack will only get bigger with hot/cold cycles and could lead to a possible hydro lock. Not good.
I'd dig in deeper before driving the truck much.