I pulled a double P0131 (O2 Sensor Circuit Low Voltage Bank 1 Sensor 1) from my 2000 V6 Alero w/ 104K... Any ideas? It lists somethings, but how do you know which one? Madness I tell you...

It could be an oxygen sensor, fuel too lean, etc...

Any help would be great!!

 

The O2 sensors are used to determine the fuel mixture. It's probably time to replace that sensor. They are about $90 at Autozone, and they will loan you the tool to do it. It isn't hard.