OBD 2 codes

[Sackett2]

Don't forget to use the O2 spacer on the downstream O2 not the upstream I don't use them but I have seen them on Subees.

LOL, Guess what kind of shop I work at?

3 years ago I went through a class that played with the rear o2 sensor, sent false info into the computer. End result, A rear o2 sensor can control fuel trim more than the manufactures tell us. After that class, I became a firm believer in not adjusting what the engineers made. Ford is starting a data called "aft fuel trim" on their scan tools.

 

[orezok]

Also a "unofficial" option is a o2 spacer, this lifts the o2 sensor out of the exhaust streame and fools the computer. I see these on tuner cars a lot, where they have exhaust mods.
RalliTEK O2 Sensor Spacer
Re-flashing generally won't work, the re-flashes are meant to refine the cars function with OEM equipment/problems, not aftermarket mods

It's a lot cheaper to just go to your local auto parts store and buy the $2 "anti-foul" plug spacers. You might have to drill the centers out and screw 2 together to get the increased depth necessary.