Engine Code P401

[hostile500]

Hello everyone
Has anyone ever had the P401 EGR recirculate insufficient flow code come up?
I have a 13/14. the light has never came on and I have 15k miles on the car. I put an O/R X pipe on over the winter and the light stayed off along with the O2 sensors went ready. One weekend i decided to run 5 gallons of C16 leaded fuel in with about 5 gallons of 93 for a dyno day. After that day the P401 code keeps coming up. I put the stock H pipe with cats back on and went back to 93 octane but the light keeps coming on. Any help would be great.

 

[07 Black Beauty]

Leaded fuel burns slower from what I've read, may be why the EGR is sensing insufficient flow? I've also read the o2 sensors don't like leaded fuel

 

[hostile500]

yeah the O2 sensors didn't have any problem with it. They even went ready when it comes to emissions here in NH. I guess im trying to find out if any has ever had one of these go bad. From what ive heard they very rarely do