Hi,
I bought a mac air 2012 very cheap, because the customer didn't want to fix. After reflowing the ram chips the laptop works fine, I tested the ram and no error. But The fan goes at max speed after few seconds. Running the Apple diagnostic finds an error 4SNS/1/C0000008: Th1H--124. and the cpu usage is like 300%, After disconnecting the webcam cable that on the 2012 model is on the IO board, the laptop, the laptop runs fine, and running the apple diagnostic finds no errors. So the problem is related with the webcam, but I suspect the problem is no the webcam but the light sensor....