3g hemi gas mileage

Stacked360 said

I was under the impression the second O2 sensors are for checking catalyst efficiency only, and the upstream are what determines the fuel trim?

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While that is the case,when the computer receives no feedback from the downstream sensor, it reads it as lean, and can cause the upstream sensor to overcompensate. I would be interested to see a wideband O2 installed to see what is really going on.