What part of the MacBook Pro 13-inch 2.4 GHZ (Mid 2010) logic board is what sensor?
This issue is definitely related to the logic board. There is definitely damage to the board from the liquid spill and likely ESD damage from when you replaced the MagSafe board. 

There is no supported way to replace or find a temperature sensor on your model MacBook Pro. In order to replace a sensor on one of these boards you'd have to solder off the old one and solder on a new one. Since no one sells temperature sensors for the boards that integrate them, it would be a nearly impossible feat. 

I'd recommend taking it to the Apple Store or an Apple Authorized Service Provider for a full repair. They may not be able to service it since you've serviced your own machine.

I know this isn't the news you were hoping for, but I hope it helps.