Chosen Solution
My MacBook Air (mid-2012, A1465) recently started running very slow. Activity monitor show Kernel using >300% of CPU. Running the AHT consistently gives the following result:
Alert! Apple Hardware Test has detected an error: 4SNS/1/C0000008: THSP— 124
I have reset NVRAM/PRAM as well as SMC and done a clean reinstall of OSX. None of this made a difference. From what I have found on Google, this error indicates a bad temperature sensor at the hard drive (SSD in this case). I’m wondering if anyone knows where this sensor is located. Is it on the system board or on the SSD drive module. I’m hoping it’s on the SSD and that replacing it will also replace/fix the temp sensor. Any advise on how to fix this problem would be very much appreciated.
THSP— 124 is Thunderbolt sensor. Without knowing your specific board model, I assumed it’s 820-3208. You want to check Q5520, R5540, and R5541. One of these components is likely at fault, causing the error code you’re seeing as well as the slowness. You will need a schematic and boardview of your board version as well as a multimeter and soldering equipment to troubleshoot/fix this.
