Do you have an after market filter on it? I know I got that code when I put a freshly cleaned and re-oiled K&N on my wifes car. After a few months the code showed up and I was getting pinging under hard acceleration. I cleaned the MAF put the old paper filter back in and didn't get that code again. But around the same time I was also getting the EGR code and changed out the DFPE. If your DFPE sensor isn't functioning right you should have the excessive flow code. Still haven't heard of someones EGR actually stop working it has always been the DFPE. Good luck.
