What are the names of the 4 Oxygen sensors on a 03 Cadillac CTS?

Question

I believe it is Bank 1

Bank 2

Upstream

Downstream

But someone said something about sensor 1 and sensor 2. I'm confused?

Answer 1

there is bank 1 primary, secondary. then bank 2 primary and secondary.  

Answer 2

Bank 1 Sensor 1 Bank 2 Sensor 1

Catalytic Conv. Catalytic Conv.

Bank 1 Sensor 2 Bank 2 Sensor 2

Answer 3

On a V-Engine,be it V6 or V8,there are two banks (2 cylinder heads,2 exhaust manifold,each has its own catalytic converter)name Bank 1 and Bank 2.Each bank has 2 O2 sensors,The one that sits in front of the catalytic converter is sensor 1,after the cat is sensor 2.