2012 Chevy sonic O2 sensor help

[Madman227]

Hey guys so I’m throwing a code for a bad Cadillac converter or oxygen sensor so I plugged in my scan tool and I’m getting voltage to both of my oxygen sensors but I’m only Getting a short term fuel trim off of my upstream sensor my downstream sensor is not reading anything but it is getting voltage at first I thought it was bad so I replaced it and it was very very black at the top so I was hoping replacing would fix it but it has not done anything at all it is still reading that the oxygen sensor is not getting any short term fuel trim but it is reading perfect voltage in all regards

 

[BigLee]

The second 2 sensor doesn't have a
"fuel trim". That's why it says "n/a".
Only the primary sensor has fuel trim tables.
And your 2nd sensor voltage looks pretty normal. It typically should stay in the .6-.7V range, except under decel fuel cut when it should drop to 0v just behind the 1st sensor.
Only th 1st sensor has the continuous voltage swings to it.

 

[Scott2000]

The downstream o2 sensor isn't reading right. It's reading as if the catalytic converter is bad or the sensor is bad. Change the second o2 sensor and if it's still reading the same, you're gonna need a new catalytic converter