Were are the O2 sensor located? Front and rear.

The inspection was done by a Goodyear mechanic doing an emissions test, at there shop. 1 WPC C5010144277BOS OXYGEN SENSOR 2 WPC C5010144275BOS OXYGEN SENSOR

ok, did they do a real diag or is he guessing. in most cases, o2 sensor codes are set because the o2 cannot do its job for something else in the system. in 95% of the cases, they are not at fault. what were the code numbers?? Roy