Question…
I only have 2 Oxygen Sensors in this vehicle. One Upstream and one Downstream.
If I were to change the Upstream should I change the Downstream as well??
Why I’m changing my upstream you ask??
I am seeing noticeable affects off the vehicle running rich. Too much gas consumption than normal
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Doubltful that it’s caused by the oxygen sensor. Most common cause of reduced MPG is worn spark plugs. And to answer your question, no, you don’t need to replace the downstream because it has nothing to do with calculating air/fuel mixtures. Its only job is to monitor the cat performance.
I changed all the sparkplugs already :/ the problem persists
You don’t have to do them both at the same time. Make sure you don’t have any exhaust leaks prior to the upstream as that could be the issue, if it is the issue. I would check for codes with a scan tool. If you have a bad O2 sensor, the scan tool should tell you.
Tried an obd scanner. Don’t have the real time scanners :_
A simple scanner would be enough to tell you if you have a bad O2 sensor, the fancy scanners are not needed for that. I would bet on your O2 sensors being ok. One thought that came to mind, is your temperature sensor ok?
You don’t need to change the downstream at the same time. I think the downstream mainly measures catalyst efficiency. And the up stream is air fuel?