I bought my truck with a TPMS warning light on the passenger rear, but chalked it up as just a sensor being messed up.

I had my tires rotated with my last oil change, and when I got into the truck to leave the warning light was on.

To double check it was just that sensor I brought up the screen. to my surprise, the false/no reading didn't move with the tire, it stayed in the same location (PR)!

I did check, and can confirm, the tires were in fact rotated, and the sensor that wasn't reading before, is now giving a read out.

So if it isn't a TPMS sensor, do you guys have any idea what is it?