Just like a car, your computer can generate codes to indicate any problem(s), allowing you to determine your next step. Even though this may sound too advanced for most people, this is only diagnosing the problem, not fixing it and it is much easier to do than you might think.
To run the test, you will need access to the Internet and this test may take 15 minutes or more. Hold down the “D” key and then start your computer. Continue to hold down the key until you see Internet recovery options. After a few moments, you will be able to select your network, meaning the way you connect to the Internet. If it is wireless, you will be required to enter your password.
When it shows Apple Hardware Test, select your language and then select the arrow at the bottom to continue.
When the next window opens, it will automatically begin a probe of your system. This probe must be completed before you can run the test. When the probe is complete, select the test button. If you check mark the box Perform extended testing, the test will be more thorough and will take a much longer time to complete.
If you find an error code displayed after the test is finished, you can call Apple’s Genius Bar and speak with them about it. You may need to go into the Genius Bar personally to obtain more details about your issue(s).
When you’re done running the test, select the restart or shut down button below.
For 15 years, Scott Lindsay has helped tens of thousands of people better their skills, publishing more than 400 articles about Apple and Microsoft software, the computer and the Internet. You can reach Scott for comments or questions at ScottLindsay@live.com.