Actual hardware failure is rare, but it happens from time to time. A common hardware failure is random-access memory (RAM). The Apple Hardware Test can check your Mac’s RAM and let you know if there are any issues. Some Mac models allow you to upgrade the RAM yourself, but in general, the newer your Mac, the less likely this feature will be supported.
Apple Hardware Tests on Newer Macs
Not all Macs can use the internet-based AHT. Some must use a local version that’s either installed on the Mac’s startup drive or included on the OS X install DVD. Macs made after 2013 must use a newer version of the hardware test, called Apple Diagnostics. You’ll find instructions for testing newer Macs using Apple Diagnostics at Using Apple Diagnostics to Troubleshoot Your Mac’s Hardware.
Macs That Can Use Internet Version of AHT
Use the Apple Hardware Test Over the Internet
Now that you know your Mac is capable of using the AHT over the internet, it’s time to run the test. To do this, you need a wired or Wi-Fi connection to the internet.
End an Apple Hardware Test in Progress
You can stop any test in process by clicking the Stop Testing button.
Apple Hardware Test Error Codes
The error codes generated by the Apple Hardware Test tend to be cryptic at best and are meant for Apple service technicians. Many of the error codes have become well known, however, and the following list should be helpful:
Perform Additional Troubleshooting
You can perform additional troubleshooting for RAM, hard disk, and external disk problems. In the case of a drive, whether internal or external, you can repair it using Disk Utility (which is included with OS X), or a third-party app, such as Drive Genius. If your Mac has user-serviceable RAM modules, clean and reseat the modules. Remove the RAM, use a clean pencil eraser to clean the RAM modules’ contacts, and then reinstall the RAM. Once the RAM is reinstalled, run the Apple Hardware Test again, using the extended testing option. If you still have memory issues, you may need to replace the RAM.
