Chosen Solution

Replaced the logic board and ssd in my MacBook and now the fan is stuck at max speed. I have tried to control the fan with Macs Fan Control but it doesn’t work and TG Pro is reporting normal temps but TG pro sometimes reports that the fan isn’t on because temps are so low.

I have tried reseting PRAM and SMC with no luck

Definitely sounds like it could be a sensor issue. I would agree to @danj ‘s recommendation to run diagnostics. Trying to make sense of the various names for sensors can be a bit of a nightmare (different apps call the sensors different things, which don’t match with what Apple calls them). I believe the sensor Dan referred too that’s on the I/O board is technically for the Wireless card (but no wireless card sensor in the TGPro list). There’s a chip on the back of the board in the upper corner, near the fan which also functions as a sensor for “near fin stack” (as well as collecting other thermal signals and talking to the SMC) which I might also interpret as heat pipe outgoing air (although, as I’ve said it’s hard to know, since nomenclature differs). If that’s the case, sounds like your new board might be faulty. I might also check your SSD. Is it an OEM drive? If not, I have seen third party drives cause odd thermal readings as well, so I might try putting the original SSD in if possible.

This is all with the new logic board? If it is you have a bad board as the SMC logic is having issues dropping the heat pipe outgoing air temps and fan RPM’s. The heat pipe outgoing air sensor is on the I/O board so you may want to make sure its properly connected and/or replace it.

The Fan is via this connection point on the logic board. Make sure the latch is pressed down.

Update (11/29/2021) Here’s the heat pipe outgoing air sensor in the schematics

Update (11/30/2021) Here’s a better image of the sensors placement

just to verify that Q5871 is the heat pipe outgoing air sensor. I show it on here

which appears to be near the SSD on the bottom side of the board. This is the sensor for TA0P

It is not located anywhere else.