where are the )2 sensor located on a 2008 Pontiac g6 4 cylinder

Question

Where are the o2 sensor located on a 2008 Pontiac g6 with a 4 cylinder do you have a pic

Answer 1

Number 3 is the upstream or sensor 1, this is engine management sensor, number 4 is downstream or the catalytic monitor also refferred to as sensor 2.