Yep, check for exhaust leak first.
If nothing found, see if you can post a screenshot of your complete data screen.
We'd need to know all kinds of stuff...
O2 sensor info over time, idle
Map sensor voltage over time, idle
Coolant temp sensor voltage over time, idle
TPS
Etc
We can look for abnormalities.
Still.... it does sound like the O2 sensor is reading a false lean code.
Which the PCM would compensate for by adding fuel.
If there was a lot of false air, the PCM would add lots of fuel.
Do you have a chip? I thought the max short-term compensation for fuel trim in GM was +35%...... +49% just doesn't make sense for a stock GM vehicle.
MAF voltage over time, idle
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