Cleaning the EGR valve in your vehicle, by hand, has some steps that you should follow to do it the correct way. There is a self made "EGR cleaners for dummies" set up at : http://www.icess.ucsb.edu/~greg/rodeo/egr.htm. You will know when the EGR valve is clogged or not functioning correctly because it can cause rough idling or valve knock, this is when you should have your EGR valve checked out.
