Mitsubishi Repair: Eclipse EGR Code p0401, free scan tool, egr valve

Question
My friend purchased a 1996 Mitsubishi Eclipse RS 2.0L non-turbo last summer and shortly after the check engine light came on. The first time it appeared we checked it with a scan tool and the code was P0401 EGR insufficient flow detected.  I replaced the EGR valve and cleaned the EGR tubing. Then a week or so later the check engine light came on again and he took it to a Mitsubishi dealership for diagnostics. The code for the catalytic converter came up so I replaced that. Then about a month later the check engine light came on again.  My friend not having the money for diagnostics let it go and the check engine light came and went mysteriously. He just dealt with the light on until recently when I noticed in an ad for autozone that they offer free scan tool checks if your check engine light is on. He went yesterday and they told him the code number and what it was. It is the code for the EGR valve again. I don't know what it could be seeing that we replaced the EGR valve and solenoid and cleaned the tube. Could it be the PCM acting up ? Any info would be greatly appreciated.

Answer
Andy,
The free PCM reading that AutoZone does is helpful, but not always 100% accurate.  They use a universal reader and all manufacturers have proprietary codes.  The EGR code is pretty common, but there could be relative components that are actually the problem.  

Fortunately, that car has a built-in way to check what your PCM is actually logging the errors for.  You can access this site for the procedure to retrieve the codes yourself and see what the codes mean:
http://www.2gnt.com/nuke/modules.php?name=Sections&op=viewarticle&artid=8

If you perform the procedure listed in the URL provided above and the only code still points to the EGR valve, the problem could be the harness or connection to the valve.
Good luck!