Ok, here's the scoop. I have a 2000 F-150 4.6L with 103K on it. MIL light came on some time ago and the scan tool gave me the P0401 code. Me being the smarty pants that I am, I replaced the EGR valve only to have the problem persist :-(
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Hmm... Visited this forum to find info on cleaning the EGR ports in the throttle body, which brings me to the first question. When I took the throttle body off, I certainly saw carbon but not to the extent that others have talked about. First, where are the EGR ports exactly? After removing the throttle body and looking straight in, I see a fairly large opening on the right and a smaller one just behind it. No build up on them, but I cleaned them anyway. Reaching down I can feel two holes on the inside of the bend, but can't feel any buildup. Again, I clean those as best I can from that angle. Put everything back together, replaced the plugs while I was in there and everything runs great. For a day. After driving around today, the MIL lamp lit this evening and again it was the P0401 code.
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So I dig into it again. I check the reference voltage and resistance of the EGR valve control solenoid and that looks good. I check the ref voltage on the DPFE sensor and that looks good. So I pull the EGR valve control solenoid and according to the Chilton's manual you shouldn't be able to blow air through the valve and I can. According to the manual the valve is defective, but there is what I believe a typo in that section that makes me question that statment.<br>
So my next question is, is the valve defective if I can blow through it with no voltage applied to it?

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TIA

Ed - Who is completely frustrated by this

 

Hey Oddsix.
After you remove the throttle body, the part that goes between the throttle body and the intake has two ports in the center that get clogged to the point that its hard to open up on the truck. Remove this elbow part and clean well. You will need a new gasket for the throttle body, and egr valve, and the (Pleminium) gasket. I cant spell something i cant say.

Dave P.

 

Thanks bosshoss. I pulled the throttle body and plenum together today and once I did that I could clearly see the two EGR ports. About 10 mins of work to clean, put back together reset the MIL light and all is well again.