I wish I'd have found this forum 2 weeks ago. bank 1 is whatever side your #1 cylinder is on. if you had a V6 or V8, bank 2 would be whatever side your #2 cylinder is on. but since you have a 4 cylinder, you should only have bank 1.

sensor 1 is upstream - that is, before the catalytic converter. usually in the manifold or header. sensor 2 is downstream, after the catalytic converter. vehicles like yours, made after 1996, have OBD2 and all that stuff makes a difference. older ones usually only have one sensor.

Dan

 

but since you have a 4 cylinder, you should only have bank 1.

If you would have found it 2 weeks ago, you would have given me the same response everybody was giving me. That crazy ass look and immediate dismissal that my 4-cylinder car has 4 oxygen sensors. Examine the photo a little more carefully. This thing has 2 upstream and 2 downstream sensors....2 banks, 2 sensors each bank. If you don't believe the illustration, I'll go outside right now to get a digital photo.