I need help?

The check engine light is on on my 98 Honda Accord EX. It's a 4 cylinder automatic.....I took the car to the local independent shop (not a Honda Dealer) and they said the code shows it needed a new EGR Valve ....they replaced it, but after a few hundred miles the light come back on....this is the third time it has happend. The shop replaces the valve or clean it at N/C.....but the light keeps coming on....

Could it be something other than the valve .... any suggestions

Thanks
Bob