2015 Chevy Tahoe lt constant code P0156

[Merch619]

I got a 2015 Tahoe LT 5.3 with the 6l80 transmission. I have had the transmission rebuilt and when I put it back in I started getting a code p0156 occasionally two other codes p2”97 and p2099. I’ve changed the MAF sensor, air filter, plugs, wires, exhaust and manifold gaskets, flex pipe, all 4 o2 sensors (multiple times and brands) and swapped the second sensors to the opposite sides and it still reads p0156. I’ve looked over the wiring and can’t find anything that looks corroded or broken. I’ve checked the fuses and they look fine and tested good as well.

Is there a frame or body ground that would just mess up the one sensor? I did have the dod tuned out of the computer and trans has a custom tune done to it if that matters?
It has a rough idle and shake in park or in drive and driving.

Anyone have any advice or suggestions on what could be wrong?

 

[Fless]

Is that a P2097 in your post, or another?

P0156 is related to the downstream O2 sensor on the passenger side. I would guess that you've done quite a bit of testing, and that you've repaired all the exhaust leaks.

That leaves circuit integrity; visual inspection isn't enough. The heater circuit should be load tested with, say, a 3 or 4A test light at the O2 sensor connector, and the reference voltage and ground in that connector be verified. Also have the PCM connections been inspected and cleaned?

Some testing suggestions here: https://www.obd-codes.com/p0156

Does the downstream sensor voltage reading stay low, or high?

If there is freeze frame data for that code, what do the PIDs return for values? Anything stand out there?