Check engine prob. EGR press diff switch

[parkerwa]

Can someone help? I have a 98 expedition 4x4 with 5.4 L engine122K miles on it. I have the check engine on (for about 4-5 months now) and my first step into correctiong problem was to get autozone to hook computer up. they said EGR valve -- I check removed and cleaned seemed ok to me so I put back on and reset light . Light came back on . I talked to a local mechanic and he said 90% sure it was the Differential pressure switch , so I replaced it with on e from Auto zone - reset light and 30 minutes later light back on . I took to Ford place and had it hooked to their computer as I know theirs tells more and the tech said it was saying the Differential Pressure switch for the EGR valve needs changing. Well I replied I just changed it and there is a new one on. He said it must have been bad out of the box. I took it back and exchanged it for another new one and the light is back on...It is not the Diff Press Switch and the computer is saying it is. I checked it with the prociedure in the Haynes manual and it looks like all voltage measurements are close. What next? does something need cleaning ? holes need clearing out?

 

[exsport]

Did you or your mechanic clear your D.T.C.'s (diagnostic trouble codes) from your truck's computer? It may be that even though the "check engine" light was reset the computer may still beleive that the problem exists because the codes have not been cleared...
just an idea, not sure if it will help....