1996 G20 5.0 motor o2 sensor

[jr32560]

okay my van says o2 sensor bank one sensor 2 is defective--these parts places keep saying downstream-this van has 3 o2sensors prior to the cat I'm kinda lost here it has one close to the manifold on drivers side one close to manifold on passenger side one before the cat one after the cat-----

any help would be great~~~~

[Spaznaut]

I'd google the trouble code and see what comes up on the location of the sensor.