Can Apple’s Hardware Test Detect Hard Disk Failure?

Like an increasing number of computer manufacturers, Apple includes a built-in hardware diagnostic test in their systems to help users or system administrators diagnose hardware faults. Apple Hardware Test (previously, Apple Diagnostics) comes in short and long variants, will mildy stress components such as an iMac or MacBook’s processor, logic board controller, fan motor, RAM modules and of course the hard disk. For the latter, you would hope that the test is fairly accurate so that your (or your user’s data) is not put in jeopardy.

What does “4HDD/11/40000000: SATA (0,0)” mean?

When Apple Hardware Test does detect a fault with your disk, it will display the rather cryptic error code “4HDD/11/40000000: SATA (0,0)”. This basically means that the AHT has discovered that your hard disk is failing.

How Accurate is Apple’s Hardware Test when testing a hard drive?

But, unfortunately, Drive Rescue has come across a substantial number of cases where the Apple Hardware test (short and long versions) did not detect a fault even when a hard disk was failing.

There are several reasons Apple’s in-built disk diagnostic utility cannot be relied upon:

  • Apple’s Hardware Test performs a random scan of the tracks of your hard disk. It does not scan your whole hard disk. The test could easily miss sectors of your disk which are failing.

  • Apple’s Hardware Test cannot detect firmware problems.

  • Apple’s Hardware Test will not always be successful in determining weak or unstable read/write heads. Often, during tests, random reads are short. In real-life, reads of contigious files can take much longer stressing the disk- heads much more.  

  • Apple’s Hardware Test cannot detect electronic issues with your disk’s PCB.

  • Apple’s Hardware Test cannot detect whether you have a corrupt HFS+ or APFS partition table.

In summary, the in-built testing hard disk which Apple provides with their iMac, MacBook and Mac Mini systems is just rudimentary disk diagnostic tool. It should not be regarded as infallible litmus test of a hard disk’s health.

Drive Rescue Dublin offer a complete data retrieval service for Apple Mac computers in Dublin. We recover data from dead iMacs, MacBooks, MacBook Air and Mac Minis. http://www.datarecoverydublin.ie. Prompt and professional service.