Chosen Solution

Trying to fix a friends MacBook Air 13” from Early 2015. Fans constantly running at full speed & CPU is being throttled at .8 Ghz. I downloaded iStats & see that there is no reading for the “fin stack” sensor. My question is, is this sensor on the main logic board or on the I/O board? Thanks

The fin sensor is well hidden! Its located on the I/O board underneath.