Using Apple Diagnostics
To start Apple Diagnostics:
- Turn off your computer if it is on by choosing Shut Down from the Apple () menu.
- Press the power button to turn on your computer.
- Immediately press and hold the D key until Apple Diagnostics begins.
- If you previously selected a language for the computer, a "Checking your Mac" screen will appear in that language.
If you have not selected a language for the computer, a language selection menu will appear. Select a language and then press the Return or Enter key. Apple Diagnostics will begin.
- The basic Apple Diagnostics test takes approximately 2-3 minutes to complete. As the diagnostic runs, a progress bar indicates the time remaining in the test.
- If no issues are found: A "No issues found" message appears.
- If issues are found: Apple Diagnostics finishes and displays a brief description of any issues it finds along with one or more reference codes and additional instructions. Be sure to make a note of these reference codes before continuing.
- To exit Apple Diagnostics, click Restart or Shut Down at the bottom of the screen.