So recently I had this code and with the mileage that is on my car I went ahead and replaced the EGR valve instead of just cleaning it. Well, after a twenty minute ride on the highway the code was back. I did some research online and found that GM has had some common EGR valve problems that have caused this code to re-emerge even after a new part is installed.
Other GM related forums and OBD2 sites out there stated that you should follow some specific steps when dealing with code P1404 after replacing the egr valve.
They say as follows:

1. Disconnect the wire harness from the EGR valve.

2. Turn key ON and erase the trouble code(s) from the car's computer AND TURN KEY OFF IMMEDIATELY WHEN THE SCANNER SAYS CODES HAVE BEEN ERASED. DO NOT TURN KEY ON BEFORE YOU RE-CONNECT EGR WIRE HARNESS.

3. Re-connect EGR wire harness and your problem should be fixed.
Pontiac Grand Am: DTC code P1404 - Car Forums - Edmunds

Has anyone here heard of this? I know that if the code comes back I will try this as I have cleared it again.
Thanks for any input.

 

P1404 Diag

 

So, I my code P1404 came back on my way to work today. Before I left work to come home, I followed the instructions above and the entire ride home the CEL did not come back on. My drive is about 25 miles highway one way. Before I did the trick, 5 minutes of highway driving and the light would come back on. So it looks like the CEL is out and everything is good. I'm going to wait till the end of tomorrow before I put a final stamp on it but so far so good.

 

Drove to work today and back home and no CEL. This fix gets my stamp of approval. So if you change your EGR valve and the light comes back on; use this technique.

 

Thanks for this write up. I had this code pop up last week only to clear it and had it keep coming right back. I read this and followed the instructions and the code is gone. I can confirm this one definitely works!!! Thanks again to the O.P.