AHT Fix - restore the Apple Hardware Test on your (old) Mac

This article applies to you only if you have an old Mac that was released before June 2013. Yes, this article is about old hardware that is still out there. It is even still traded on ebay for exmaple. So I am pleased to announce AHT Fix. The tiny app restores the Apple Hardware Test on older Macs (released before June 2013) where Mac OS X, OS X or macOS has been reinstalled from scratch. Please also have a look at the "Implementation details and credits" in this article.

The Problem

„Apple Hardware Test (AHT) contains a suite of diagnostics that will test the hardware of your computer. […] If your Mac was released after June 2013, you will use Apple Diagnostics rather than Apple Hardware Test (AHT).“ See also https://support.apple.com/en-us/HT201257

If you have reinstalled an older Mac from scratch, the diagnostic tools might no longer be available. If there is content in /System/Library/CoreServices/.diagnostics you are affected. Unless you have the original disks that came with your Mac, there seems to be no way to restore the AHT.

The Solution

AHT Fix. You can grab a copy from https://github.com/jonelo/ahtfix

The application will determine the model of your Mac, query an Apple server, download the appropriate AHT binaries and restore it on your Mac. And once restored you just need to follow the instructions at https://support.apple.com/en-us/HT201257 in order to perform all hardware diagnostics on your Mac.

Note: Starting with El Capitan (OS X 10.11) there is a new feature called System Integrity Protection (SIP) that prevents the modificaiton of a number of operating sytem directories by default.
In order to use AHTFix on El Capitan and later you have to disable SIP temporarily.
See also https://www.macworld.com/article/2986118/security/how-to-modify-system-integrity-protection-in-el-capitan.html

System Requirements

• A Mac, released before June 2013
• Mac OS X 10.6 or later
• SIP disabled if you run El Capitan (OS X 10.11) or later
• An internet connection (any bandwidth)

Implementation details and credits

On https://github.com/upekkha/AppleHardwareTest you find detailed instructions from Claude Becker how to restore the AHT manually. I put those instructions (and a few more) to a bash script so that you can restore the AHT in a comfortable way.

I also would like to thank Apple for hosting the AHT binaries on their servers. That really helps users to restore the AHT on Macs that would be otherwise incomplete.