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Are you getting any malfunction codes set or does your scan tool read live data voltage from both of the rear catalytic converter O2 sensors? What was the physical location of the sensor that you replaced? Bank One on this engine is on the driver side and a bank two is on the passenger side just want to clarify that.
What was the reason for replacing bank two sensor one as you indicated above? The location that you just gave me the driver-side post catalytic converter sensor is Bank one sensor two. Did you previously have a malfunction code for this sensor or a 420 code or a 430 code for catalyst efficiency?
Okay that is good I just wanted the clarification to make sure we are on the same page. Since the sensor was replaced that original code has not come back after 700 miles of driving and the only problem at this point is it will not ready on for the catalyst monitor correct?
Click this link and download the drive pattern information. The link will time out. This drive pattern has to be specific as far as engine temperature and ambient temperature correlation. This pattern is for an oxygen sensor system not an air fuel ratio sensor system they usually only use those in California on this year. Ideally I would like to watch the voltages of the post-catalytic converter oxygen sensors if they are seeing any oscillations in voltages from .1 up to .9 V it could keep the computer from letting the monitor test pass yet not bad enough to flag a cat failure code. You could have a catalytic converter that is starting to fail. Without monitoring those voltages and making sure their staying flatlined and slowly rise and fall on acceleration and deceleration there is no way to know. Run this drive pattern and see if it passes. If it does not pass after multiple attempts driving the specific drive pattern then you will need to get into checking the catalyst efficiency and voltages of the rear sensors as I described. If that checks okay then it's possible you could have a logic fault in the computer itself but that would be extremely unlikely. Please do not forget to rate the assistance that I provided you at three or higher and any bonus is greatly appreciated. If you need additional information feel free to reply and I will get back to you.