Check Engine Light

[2010AveoLT]

There really isn't any need for complicated diags here. Unless you see an obvious issue with the wires leading to the post cat O2 sensor, just replace the thing. 2009 CHEVROLET AVEO Oxygen Sensor

do you Know HOW MUCH a 09+ Oxygen Sensor Costs at a Parts House? ITS ON PAR with the price you'd get if you waltzed into a GM Dealership Parts Department ($250)! Throwing VERY EXPENSIVE Parts at a Problem and seeing what sticks IS NOT the Proper Way to Fix a Car. it DOES NOT Fix the ROOT CAUSE of the Problem. and don't get me wrong, RockAuto is Fine for lots of different parts, but in some Instances like if your Vehicle Registration was Tied to your Emissions Test (like in California, New York, and some parts of Indiana (where the OP is From) you need those emissions parts VERY QUICKLY.

I've done Research on how GM wired the Downstream Oxygen Sensor in the 09+ cars, and the Downstream Oxygen Sensor Circuit is a LOT MORE Complicated than you think. They actually routed the signal THROUGH the UBEC (Underhood Bussed Electrical Center AKA the Underhood Fuse Box) to the sensor from the PCM, and the run the Return Signal pretty much along the Same path on a Different wire BACK Through the UBEC and back to the PCM.