Q&A

Of the four wires going to the rear O2 sensor one wire is red/white ensure this has battery voltage (this supplies power to the heater in the rear O2 sensor, the brown wire grounds the heater circuit in the computer.) There is a service bulletin #121097 (perhaps a recall) dealing with reprogramming the computer to reduce the occurrence of false Check Engine Light illumination flagging defective O2 sensor operation.

hi this is a pretty simple engine with lots of details it could from your pcv valve strait under the intake manifold it has a tube comming from the crankcase to to the pcv valve than goes to the valve cover.or it could be from the anti-pollution pump if you have one it blows cold air in the headers if it doesnt work it make condensation and higher heat so the sensor acts up
it could be a ground wire ,or ignition wire fuel pump get me the code numbers and ill see what i can do