iMac 21.5 "& 27" error 4SNS / 1/40000000: TH00-9.000 after replacing HDD 4SNS / 1/40000000: TH00-9.000 error after replacing the hard disk in the following Apple models that do not have an external disk temperature sensor : - iMac 21.5 "A1311 (model 2011) - iMac 27 "A1312 (model 2011) - iMac 21.5" Retina A1418 (models: 2012, 2013, 2014, 2015) - iMac 27 "Retina A1419 (models: 2012, 2013, 2014, 2015) My method does not require any financial outlays in the form of adapters, additional cables or modules, is non-invasive for computer cabling, fast and 100% effective. It eliminates all of the symptoms described below, including displaying an error in AHT. Symptoms: - very slow operation of the operating system, - task kernel 100% and more in the Activity Monitor (constant, full CPU load), - high fan speed (on the A1311 / A1312 models of the HDD fan, on the A1418 / A1419 models of the main fan), - error 4SNS / 1/40000000: TH00- 9,000 in AHT tests (Apple Hardware Test - triggered by holding Alt + D keys while the computer is starting up). Cause: New hard drives that are not branded with the Apple logo are inconsistent with the Apple SATA standard that provides for a temperature sensor located on the disk electronics board. Apple discs use pin 11 SATA power connector (15-pin) to output voltage from the temperature sensor. Below is the difference between a standard SATA connector and an Apple SATA connector: Fig. 1 and 2 - pinout of the SATA power connector (on the left a standard pinout, on the right Apple pinout) Solution: Just before mounting the drive, connect pin 11 to pin 12 of the SATA power connector with a tin drop, as on the pictures below: Fig. 3 and 4 - SATA connector pins 11 and 12 (2.5 "on the left, in which the soldering points of the connector are available without disassembling the electronics, on the right a 3.5" disk, in which the soldering points are not available from the outside and it is required to disassemble the electronics board) ==========
Thank you for your solution, I would just like to know if it also applies to replacing the HDD with an SSD. Thanks for your advice, I'm not an expert, just a user and a hospital chaplain. Martin My iMac (21.5 A1311 2011) fell out of nowhere. The screen first split, the right part was the left and vice versa, and then it became blurry and that's it. I followed apple support's advice to boot the iMac from macOS Recovery and it doesn't work. The computer will find the local boot disk, the logo and download process will appear, but after the process is completed line will disappear, leaving only a blank white screen. Or external to the server it finds a rotating country logo with the download process and after it's done, the same thing again, a white screen. It should be added that I managed to run the hardware test and it reported an error: 4SNS / 1/40000000: TH00-9.000. A year ago I replaced the old HDD with an SSD and installed MacFanControl. So far, everything has been running smoothly and perfectly.
