You might also experience P0402 excessive flow. I had both 01 & 02 at the same time. Ended up finally being the "DPFE" sensor that has two rubber hoses attached to the tube feeding the exhaust gases from the rear manifold to the Egr. It only took it 6 months before it finally gave up the ghost. Intermitents
This is a fun one to chase and catch, even with a laptop w/OBD II software, Ford CD manual and of course the all the CEG'ers help.
If it does turn out to be the "DPFE" make sure to get F77Z-9J460-AB it's plastic/revised and suppose to last longer.
If you have the time find someone to give you a discount. It's suggested retail at most dealers is around $75. My cousin has a shop and got for me from a dealer for $35. What I'm getting at is it's has high mark-up.
Paul
