P0401 Code on Acura CL

Just replaced the EGR valve on 1998 Acura CL and reset the code and then the Check Engine light came back on. The code is P0401 (Insufficient Exhaust gas recirculation), the EGR valve is bad. The mechanic cleaned the upper intake valves when he installed the EGR valve. Is there anything else we can do? Please advise.