So I bought my 04 fx4 screw 5.4 a little less than a year ago. It has long tube headers with no cats, no mufflers, and MBRP exhaust. The guy who owned it before me hooked it up pretty well.
I haven't had any issues until today... I was driving along and the check engine light came on. I have an edge tuner so I checked the codes on the fly. Two codes came up one was Catalyst efficiency low bank 2 and the other was FP Drive module secondary circuit. Now I just changed the FPDM so I'm not sure what that's about, and The truck runs and drives fine. I cleared both codes through the edge tuner and drove another 10-15 miles and they didn't come back... Should I be worried?

 

Your options are:
Put the cats on
Ignore the code
Get a tune/tuner to disable the rear o2 sensors.


Bank 2 is downstream, If bank 1/upstream I would be more concerned.