P0406 Code

[nomechanic123]

I have a 2004 4.6L F-150. Just changed plugs and now is throwing a P0406 code (EGR position system voltage too high). There was nothing wrong with it prior to me changing the plugs however, I did unbolt the metal pipe that goes from the exhaust manifold up to the EGR valve, but I put it back on and made sure it was tight. Could this be the problem? Do I need to replace the gasket in there that I unbolted or is it something more serious? Oh yeah, in case the user name isn't clear, I'm no mechanic. Any help would be greatly appreciated!

[jethat]

Did you mess with the 2 vacuum hoses that run into the egr pipe? might have replaced them backwards.

[nomechanic123]

no, i didn't remove them. I just got a new gasket so I'm going to try to replace the old one and see if that solves the issue. It ran fine for about 50 miles of hwy driving 70-80mph, then the engine started to stutter real bad

[nomechanic123]

well, replaced the gasket only to find that there wasn't one on there at all. now the CEL is on and the codes are P0307 and P0316. Any suggestions?

[jethat]

what plugs did you use? Those are missfire codes po307 is # 7 2nd one back on the drivers side. Check to see the coil is plugged in good.

[nomechanic123]

i used autozone's brand. i'm gong to change the plug out and swap the coil with another one and see what happens.

[jethat]

Your going to get misfires with those plugs. Modular engines are very picky about plugs. Motorcraft only..

[nomechanic123]

alright well looks like i'm doing another plug change. thanks for the info. i'm sure i'll be back on here soon.

[nomechanic123]

changed the plugs and it runs like a top! thanks for the help!!