check engine light is on .. no codes nothing at all shows up on the screen on the analyzer

Have you tried clearing all codes? You may have an intermittent issue (electrical) that may be as simple as a loose gas cap.

... I have cleared the code twice I do get from time to time to loose gas cap indication .. by clearing the code I mean removing the ground cable from the battery for 2 hours or more .. two places AutoZone and Advanced Auto when they've seen this before it was either a short or the computer is going bad .. comes up with a blank screen 0 nothing on the analyzer at all .. just trying to get some feedback before I spend 400 bucks on a new computer ... Thank You ...

Ford explore trac 2001 code p0401