ok so i had an o/r h pipe on then i put the stock h pipe back on...ever since then the check engine light hasn't gone away....i've taken the negative off of the battery and the check engine light will stay off for a little while, but then it come back on. the other day i cleared the codes and it said 02 sensor bank 1 sensor 2, but i do not remember what the code number was...what's goin on here? could one of the o2's be bad? how would i be able to tell this? do they o2's have to be plugged in it a certain order? thanks for the help.