Can't make sense of sensor output (old MacBook Pro under gnu/linux)

I am trying to revive an old macbook pro early 2008, macbook pro 4,1 by installing Linux (LUbuntu 20.10). I was having cooling issues which were mostly resolved by adding macfanctld, which has kept my processor down from 60 degrees idle to 45 at a consistent 3200 rpm fan speed. However, psensor is showing one last hickup. One sensor called “TGTV" is slowly heating up to 126 C after about 10 minutes of use. I've looked all over, but can't figure out what this sensor is referring to. My instinct says it's the graphics card, but I'm hoping somebody can verify that or point me in the right direction.