problem with post cat 02 bank 2.this is the bank that is opposite side that cylinder number one is located on and post cat 02 after catalytic converter.problem with 02 heater circuit.could be a problem with the 02 heater power or ground or electrical connector or bad 02 or bad pcm or computer.chances are computer is good.would have to test power and ground for 02 heater circuit and check electrical connector out or take a chance with new 02....if high miles and original 02s then would replace.pre cat 02s are called fuel control 02s and play a vital role in fuel usage and fuel trim than post cat 02s are used mainly for computer to monitor catalyst efficiency.If high miles I would replace all 02s.if you go to autozone and get oe bosch with electrical connectors that match original.