O2 sensors
I unplugged my battery for 15-20 minutes and it hasn't came back on yet, lets hope it stays off, but if it doesn't, I don't think it's really anything wrong with the truck, it's just an eye site seein that check engine light on, but I may be wrong, Idk
A "cat-back" exhaust isnt going to affect your O2 sensors. What codes are being thrown? If its a heater failure then the 02 is toast. If its an 02 stuck rich or lean then you could have other issues. You could could cut your exhaust off right after the rear 02 sensor and it shouldn't hurt anything...
I did get mine done on Monday, and haven't had one bad issue. It has more get up from the line now too. Ill try to post a video, if I can figure it out. I hope you get this problem fixed. I know when something is wrong with my truck, I let it consume me till its fixed.

