I have a 2005 Honda Accord lX with the 2.4L engine. The car has 117,000 miles on it and has never had a repair on it. This morning I woke up and my check engine light was on. Went to Autozone and code PO141 came up BBHO2S12 hearter circuit fault. From doing some research it appears to be a bad O2 Sensor. My question is what sensor would it be?

 

P0141 is for the rear sensor, the one that's actually screwed into the catalytic converter.

Unplug the sensor (that plug might be inside the car, under the passenger seat).
Measure resistance between the 2 same-color wires (black?) and a bad sensor would probably read open-circuit. I think it's supposed to read something like 10 ohms if it's good.