Possible fixes to temperature sensor prolbem

Repairing the sensors would likely require swapping the parts from a dead logic board from the same model - at least some Macbooks (I haven't done this repair on your Air) use non-standard thermal sensors, and it's just easier swapping from a dead board. You then will want a logic board schematic for your model, which you hopefully will be able to find online, or else you'll need to reverse-engineer it.

There are also guys on eBay that specialize in repairing a few specific models of Macbook Airs and have old boards available as well as schematics they've helped develop themselves. As an owner of a shop that specializes in electronics repair it's usually cheaper for me to ship off a board that I don't have spares of to one of these guys than to get the parts, never mind the time involved in reverse engineering.

That being said, are you aware of the "fix" that involves running manual fan control (eg. smcFanControl) and unloading whatever kernel extension is pegging the kernel task? There's a writeup on the subject (dealing with an '11 MBA) here:

http://tech.superhappykittymeow.com/?p=2...

To see if it's a kext causing the load, as mentioned in that article boot into safe mode and see if it happens. If not, it's a kext. Locate the kext and disable.