How to use Apple Hardware Test on Macs sold through June 2013

How to use Apple Hardware Test

1. We will disconnect all external devices except the keyboard, the mouse, the screen, the Ethernet connection and the connection to the power outlet. Apple Hardware Test may show an error message if you don't disconnect all other devices, so don't forget about it.
2. Make sure your Mac is on a solid, flat, and stable work surface.
3. We turn off the equipment and we can start the test.
4. Turn on your Mac and hold down the D key on your keyboard. Hold down the D key until the Apple Hardware Test icon appears:
   
5. We will select the language and click on the right arrow. If you are not using the mouse or trackpad, you can use the up and down arrows to select the language and then press the Return key.
6. To start testing, click the Test button, or press the T key or the Return key. You can also select Perform extended testing before starting testing. This will perform a more thorough test that will take longer to complete.
7. When the test is complete, review the results in the bottom right of the window.
8. To exit Apple Hardware Test, click Restart or Shut Down at the bottom of the window.

Other details to consider

• Some Mac computers that ship with OS X Lion v10.7 or later will boot from Apple Hardware Test over the Internet if a copy of the disk is not found on the startup disk or if you hold down the Option-D keys during startup. An Internet connection via Ethernet or Wi-Fi is required.
• If you are using OS X Lion v10.7 or earlier and cannot start AHT, see if you have an OS X installation disc called "Applications Install Disc 2". Insert it into the internal optical drive or an external SuperDrive before following the steps above. If you are using a MacBook Air (Late 2010), connect the MacBook Air Software Reinstall pen drive to the USB port.