Chosen Solution
After running Apple Hardware Test I got the error code 4SNS/C0000008:Ts0P–124. Some the symptoms I observe is that the computer runs very slow and the fans are always running at high speed from the moment I start the laptop. Anyone knows what this means?
Update (04/27/2015) Okay oldturkey03, I posted an image of the inside of my Macbook 13" retina late 2012 in my first post. What’s circled in red is the SSD tray that has the solid state drive. What’s circled in yellow is where I believe the palm rest temp sensor should be located from reading your description. Please correct me if I’m wrong.
Jstervil, the problem is most likely related to the sensor of the Ts0P Palm Rest Temp sensor. The palm rest sensor is located on the hard drive cable. It is under the hard drive and up against the front edge of the machine. It may be a bad sensor or your may after corrosion, liquid spill etc. You may want to consider to download and install this Temperature Gauge Pro. It should help show you what your sensors are telling you.
I had this problem too, it is caused by the temperature sensor on the trackpad cable not being detected. I tried replacing the trackpad cable, no difference. I then read about a relationship between this sensor and the iSight camera, so I tried powering up without the camera connected (the cable came right away from the connector when trying to pull it out…) and the MacBook Pro (early 2011) now boots fine. Try it!!
I fixed the problem. I replaced the trackpad ribbon cable and everything worked fine.
