2007 Aveo O2 sensor

My check engine light came on, I had it tested at an auto parts store, their sensor said the oxygen sensor has had low voltage. I have noticed a bit of a decrease in my mileage as well.

Does the Aveo have an upstream and a downstream oxygen sensor? If so, how would I know which one to replace?

Also, does anyone know if it needs a low emission oxygen sensor or an ultra low emission oxygen sensor?

Looking around online, if it is only the one in the front of the engine, the upstream one I believe, it looks easy enough to replace though. I'm not the most technical when it comes to cars, so I do apologize if I'm asking any really obvious questions.

You will have an upstream and downstream sensor.
The upstream in the exhaust can effect your fuel trims (as can other sensors) but could have you running a ‘richer’ mixture which would degrade your mpg.

You would still want to check for proper power/signal and wiring connections before replacing.
There are quite a few previous posts you search on the forum as some have had issues with new sensors.

Cheers