Originally Posted by Zulfiqar

That looks like quite lean.

I had a similar case on a Toyota 3MZ V6 with recent work done to engine, except it was opposite. I was having black plugs and stuck lean codes on the AFR sensor for bank1.

comes out that the mechanic who did the job left the AFR sensor loose and it was sensing lean due to the air being sucked in from the threads. (It was the rear top sensor on a sienna meaning you work with braille only) You may have a sticky injector causing the ECU to pull back fuel on that cyl bank.

Try to plot both pre and post o2 sensor graphs of that bank and see which is which along with the current and learned fuel trims (short and long term) you can then try to simulate the opposite condition with either a spray like carb cleaner or induce an air leak from the evap system and see if that forces the system back to normal.

In my above experience with the toyota, I was seeing rich signal at the post cat sensor and controlled signal at the AFR (literal AFR nor an O2 on toyota) with very rich fuel trims for that bank - confirming that the AFR sensor was lying.

AFR trouble codes are not necessarily just for the whole engine - its dependant on ecu design, meaning if the ecu controls the 2 banks individually or combined (like old GM engines) you also may be having a clogged catalytic converter issue on that bank, it can severely overheat the sensor and also cause this. An air intake manifold leak can happen on one bank only too and then only that specific bank will throw a code.