Needing some help troubleshooting a pesky p0171 code. Bank 1 sensor 1 inactivity code. Ls swap from a 2003 Sierra 1500/4l60. Unfortunately I bought the car as a running, unfinished product so I don’t have a whole lot to go off of pcm looks to be from the original engine. Looks to me the previous owner had “tuned” the post cat o2 sensors out because there is only one cat per bank. I replaced rhe 02 sensor with a new oe sensor. Ohmed out the wires from the sensor to the pcm; they all tested good. Plugged in my diagnostic tool and compared the values between bank one and bank two. Bank two fluctuates like it should, bank one pretty much stays and fluctuates very little. Do I have a bad PCM or is it possible someone was playing around in the computer and changed something to where bank 1 only reads between certain values? Appreciate the help as this is the first ls swapped vehicle I’ve had.
