my check engine light will come on for a few days and the go off for a few days it has been doing this for about a month these are the codes it showing

P0156 o2 senor circut
bank 2 senor 2
malfuction

P0157 o2 senor circut
bank 2 senor 2
low voltage

P0158 o2 senor circut
bank 2 senor 2
high voltage

ND026
unknown fault
my questions are if i replace the o2 senor which one is it and is there something else that could be messing the o2 sensor

 

passenger side sensor behind the cat.
You can just have it shut off if you want. all it does is monitor the cats to make sure they work. Not that important really.

 

It would be the sensor on the right side after the cat. It could be the wiring also, but probably the sensor. Just check the wiring around the connector.

 

if it's the wiring what is it i'm looking for

 

bare/broken wire if its the wire.
Most likely the sensor tho.

 

i don't have cat i'm running obx headers and ory

 

just tune both the rears out since you have no cats.

 

Yea shut em off. If you are running Long Tubes you should have had it tuned so you aren't running rich anyway. Tuner should have shut them off.