got two codes that i cant get rid of.the po401 is Exhaust Gas Recirculation Flow Insufficient Detected.so i replaced the map sensor then the egr valve both with new delphi parts,then checked to make sure the pipe from the egr valve to the exhaust manifold was not plugged and i still get the code everyday.
the po430 is Catalyst System Efficiency Below Threshold.
i replaced the downstream o2 sensor and it went away for a few months and now it comes on everyday as well.

any help will be greatly appreciated
Thanx
Ken