O2 sensor location

[JML-3.8]

I have to replace the "upstream" o2 sensor. Looking around there is one directly behind the exhaust manifolds on each side of my car as well as what looks like one directly before and after the cat? Which one is the "upstream"? I know there is only suppose to be two o2 sensors but they all look like em to me.

1997 3.8 camaro

Thanks alot,
J

[bigairboarder44]

Re: O2 sensor location

upstream O2 sensors are on the manifolds, bank 1 is driver's side, bank 2 is passenger's side. and then i think if its bank 1 sensor 2 then thats the pre-cat sensor.

[JML-3.8]

Re: O2 sensor location

ahhh ok I forgot about the bank stuff. Thanks alot

[firebird19_99]

Re: O2 sensor location

reviving and old thread instead of making a new one. Are the o2's located on the manifold 2 or 4 lead/wire for a 99?

[ssms5411]

Re: O2 sensor location

I think thier 4 wire.

[firebird19_99]

Re: O2 sensor location

thank you