• Disconnect all external devices except keyboard, mouse, display, Ethernet connection (if applicable), and connection to AC power. Apple Hardware Test might display an error message if you don't disconnect all other devices. 
    • Make sure that your Mac is on a hard, flat, stable, well-ventilated work surface.
    • Shut down your Mac.  (If it is not shutting down, Press and Hold Power Button to Turn off)
    • Turn on your Mac, then immediately press and hold the D key on your keyboard. Keep holding until you see a screen asking you to choose your language. When Apple Diagnostics knows your language, it displays a progress bar indicating that it's checking your Mac


      • Checking your Mac takes 5 or 10 minutes. 
      • If any issues are found, Apple Diagnostics suggests solutions and provides reference codes. Note the reference codes before continuing.
      • When the test is complete, review your test results and send us a photo of it.

      • To quit Apple Hardware Test, click Restart or Shut Down at the bottom of the window.