Acura CL 3.0 Check Engine Light P0401 error code

[giants200]

Hi, I have a 97 Acura CL 3.0 and my check engine light went on few months ago with error code P0401 (EGR Insufficient flow). Did some research online and people suggested if I clean the EGR ports/passage and replace the EGR valve the problem should be fixed. I did all those but the check engine light came back on again after 100 miles. Anyone can advise what I can do next? Do I need to replace other parts as well or need to check for air leakage? Thanks in advance.

[BullShifter]

Did you remove the intake plenum to clean that port?

[giants200]

Thanks for the reply BullShifter. Yes, I have cleaned the intake plenum, and the light still came back on after 100 miles.

[BullShifter]

Hmmm, you did the whole update with cleaning/drilling the port, installing the sleeve and a new egr valve? I've never had one come back after doing the update until many thousand miles later when the port clogged again.