bank 1 o2 sensor which sensor is it
 

bank 1 o2 sensor code 172 appeared right after i replaced it i need to know which one it is so i can take it back to have it replaced, thanks

Bank 1 is always what ever side cylinder 1 is on. Sensor 1 is pre-cat and sensor 2 is post-cat.

thanks for the the reply, i checked the the harnesses and they were pluged in right to amuse myself i unpluged and plued them back in no code, i was like wtf and went on