Poor running, codes P0171 and P0172

Hi and thanks for using 2CarPros. Com.

After reading your post, it sounds like the O2 sensor itself if bad. When running in a closed loop at start up, the system runs a predetermined fuel mixture which does not involve the sensors until it goes open. Most times when a sensor goes bad, it stops working completely forcing the computer to run closed loop again. However, I have seen them send incorrect data to the computer also.

I noted that you only mentioned closed loop running. If that is all it is doing, my first guess would be the sensor itself or wiring to the sensor. Have you replaced the sensor at this point?

Let me know,
Joe