1999 E430 187,000 miles

Driving to work yesterday I got my first Check Engine Light ever(excluding loose gas caps.) Took it to AutoZone and they Pulled P0400 EGR System Fault. My immediate thought was to price a replacement EGR valve... they don't carry it. After looking around the forum it seems my problem could be the EGR Pipe? This is the first time I've actually had any work to do on her (after driving W126, W124, and W140s that required weekly if not daily repair to stay on the road.)

Any hints on getting to the pipe to clean it? location, other possibilities, helpful hints.