There are 2 sepparate codes for EGR issues - 401 is "Low exhaust gas recirculation pressure", and 441 is "Exhaust Gas Recircualtion valve failure"

If you have a 401 code, there is about a 90% chance a full EGR valve and hose cleaning will work. I had it done on my car and no check engine light since (been about 6 months). My mechanic said that older Honda 4 cylinder engines (over 150k miles) tend to have that problem. Now, he did more than just clean the valve.... he took off all the vaccum hoses from the valve to the solenoid and the intake and exhaust manifolds (and there are alot of little hoses) and cleaned them too. Basically he cleaned out all the plumbing in my car. Cost about $190.00, or 2 labor hours.

So, before you go spending $500.00 to replace an EGR valve that may or may not be bad, ask the service tech for the code number when he runs the diag. Obviously, if it is 441, then you do need a new valve. But make sure he does the system cleaning while he's at it.