2004 Chevrolet classic Where is the oxygen sensor located

Question

Where is the oxygen sensor located

Answer 1

Oxygen sensor location

On a Chevy Classic there is only one enine size. and there is only 2 oxygen sensor, the front 02 sensor is the upstream 02 sensor,  there is one at the back of the catalytic and this would be the downstream 02 sensor

 You would 2  oxygen sensor the front is the upstream and you also have one for the catalytic which would be the downstream 02 sensor