ERG error code P0401

I need instructions on how to go about repairing the EGR error code P0401 in my 1998 automatic Honda Civic Coupe HX. I already have the instructions on how to replace the EGR valve, but what if it is the chamber or the cylinoid that needs repaired. I am assuming the actual plate needs to have the hard carbon drilled out, do you have instructions on how to do that?