Where are the O2 sensors located?

Good morning, EVAPIERCE,

I have added a few diagrams for the primary and secondary O2.

Just reply back if you have any more questions.

Thank you,
Brendon

Which one is the downstream?

On the O2 sensors is the upper sensor the downstream???

Hello,

Downstream would be the one furthest down the pipe. After the catalytic converter. It is only there to measure whether or not the catalytic converter is performing the way it should be.

The upper is the upstream. So should be one on the manifold this is your upstream. Downstream is after the catalytic converter.

Do you have a trouble code that refers to the downstream O2?

Thank you,
Brendon