My 1999 Honda Odyssey Van was throwing code P0401. I did some research online about it and the consensus was that the EGR port on these vans are notorious for clogging up with carbon. I found a great download to help me do it myself at gopaultech.com You have to scroll down his article and he has a link to a pdf file that you can download and open and print off the directions that I followed. They were good. They were instructions for a Honda Mechanic to use when putting in a new teflon tube into the port hole that's supposed to stop it from caking up with carbon but over time they're all going to do it. Of course you will not be installing a new tube. It's not needed and would probably clog up too over time. Just clean up your existing hole and it will resolve the problem just as it did with mine. My check engine light stayed off and we passed Marta with flying colors so we're good to go and you should be too. I did not replace the EGR valve. I only cleaned out the port hole. The only cost for this was what I paid for the carb cleaner and that's it. I used the same gaskets for everything I took apart. The gasket for the throttle body may break or tear on you so you may want to buy one of those but mine looked just fine so I used the same one. In the end I paid far less than what Honda would have charged I'm sure. It only took me about an hour or so to do it...if that. Be encouraged. I know very little about mechanics but was smart enough to get this done and you can too.
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, Honda, Odyssey, Van, EGR, Valve, Code, P0401, Carbon, Build, Up, Cleaning, Clean, Port, Blocked, 99, 00, 01, 02, 03, 04, 05, 06, 07, 08, 09