how many o2 sensors?

[spatulahunter1]

how many o2 sensors do our cars have. my old mechanic (ill never go back to this asshole again) said he changed it while the car was there and unless there is one anyplace other than coming off the header than i think he scammed me out of 80 bucks

 

[Attack Eagle]

2gs have 2

one under the ar after the cat and one on the appropriately named o2 housing

 

[spatulahunter1]

ok, thanks.