If that is the only EGR fault it can indicate (I know the later ones can sense positioning problems to a point) then the EGR might not be opening. If it was sticking open, you'd have issues with poor idle, possibly stalling on throttle drop (like coming off the highway, or dropping the throttle abruptly after acceleration)
I know the EGR was a common source of problems on the older 2.8's and 3.1's, so it wouldn't suprise me if it was going bad.