P2270 OFT no CEL

[Suzuyans]

P2270 Code: O2 Sensor Signal Biased / Stuck Lean (Bank 1, Sensor 2)

Sold my OFT today and helped get the tune on someone's car after we installed headers on it.

First and foremost, none of his O2 sensors were taken out forcefully and we had no issue getting them off. The threads are fine. And yes, we did ensure that the O2 sensors are where they're supposed to be located at.

We flashed the correct tune and test drove it for a good 70 miles to ensure everything was right, no wonky stuff happening.

Before I left, we decided to check ECU fault codes just to doubly ensure nothing was wrong and we discovered P2270.

Now here's where it gets weird:

There was no CEL on the dashboard at all.

Is this a thing for OFT Stage 2? Because, I never had this when I had my OFT canned tune.

Only possible thing I could think of was just a fluke so we erased it. Drove for another 20 miles and it was "stored" again. Anyway, we did check the data logs and our STFT and LTFT (Ended up with -3% ish when we were done for the day) were negative so this code shouldn't be on there anyway since it was running rich. Besides that I watched the tablet and Knock Sensor didn't bulge while the IAM started at .7 and rose to a .98 indicating that we're not even running lean anyway; or at least that's my guess.

Shouldn't this code not even pop up anyway with the catless headers? The secondary O2 sensor should be disabled huh?

Is it possible this is a stored code and is not showing up because our trims remained rich?

My suspicion is that the O2 sensor just coincidentally just went and died at a weird time as well.'

EDIT: Not sure if this goes here or the tuning section. Mods feel free to move if needed.

[Suzuyans]

New information...

I've discovered that OBD-2 does codes that are pending do not illuminate CEL.

However, shouldn't something like P2270 immediately make themselves visible almost right away? I mean, it could be the sign of a malfunctioning O2 sensor and I imagine that would stay on for more than two cycles.

Also if you "clear" it, does it still have a pending status? We did clear it and it came back pending.

I do live in Texas where weather can go from 70F to 30F in a literal day...I figured the ECU freaked out when it saw the change in sudden air density and made it run lean for a bit because more air was coming in. Or I could be talking out of my ass trying to figure out why this code is pending.