Downstream O2 Sensor

I have an 06 Impala. Oxygen sensors are supposed to be changed every 100k. I changed the upstream one because I know that controls the air/fuel ratio. From what I understand, the only purpose of the post cat sensor is to trigger the cel if the cat isn't functioning properly. I recently read somewhere that this was true for cars 2005 and later but 2006 and newer cars the post cat sensor serves more of a purpose. I'm just wondering if it's worth changing since I have 131k on the odometer.

Some say, if it ain't broke, don't fix it.....

All the post O2 sensor does, is check catalytic efficiency....you can replace it if you want......but I have a feeling your cat will go before that O2 sensor will.....the sensor has nothing to do with saving your cat.....usually when the cat goes, that's when you replace the post O2.....

More often than not, that sensor will fail from a heater circuit built into it....