I have a 2004 Deville with high mileage, and I am trying to pass state emissions test (IL).

I have an intermittent PCM code of P1404 (EGR code) appearing along with SES light lit, despite replacement of the EGR valve already. Initially, I cleaned the factory EGR [nonconductive solvent] but SES codes P1404 and P0404 appeared. After replacement with the new Standard brand EGR, only the P1404 remains, but it is intermittently showing up as current, SES remains lit and history of same code is present (History only when it is cold, it seems, but otherwise it remains current after driving).

When I first replaced the valve, I threw a TPS code which I have since replaced. The car behaved differently with the new EGR valve replacement installed than it did after it was initially cleaned, (several stalls with new valve) but after maybe 6 restarts, the idle reset itself, although I still have a very slight rough-idle, almost imperceptible, but, in general performance is okay and mpg's remain as good as ever (about 26 mpg highway).

I'm pulling the trouble codes from the dash using the published technique, but I am not resetting the EGR code since replacement of the valve thinking that after XX number of drive cycles it will reset if not reappearing; however, it shows current after a period of driving it.

At this point, since new valve was installed, but trouble code remains, intake manifold was cleaned (but not vigorously, but is it not throwing an P0404 EGR Open or P0401 flow code either), I am wondering if the PCM reprogramming is needed or if it will fix this trouble code? Or is there another problem?

Again performance is okay, but need to pass emissions. Thanks for your feedback.