Apple Diagnostics is a built-in test that checks your MacBook's hardware: among others the memory, power, battery, sensors and fans. Handy when your Mac behaves strangely and you want to know whether the hardware is the cause. This article explains how to start Apple Diagnostics on a Mac with an Apple chip and on an Intel Mac, and how to read the result.
Blue Apple repairs MacBooks in Amsterdam. Apple Diagnostics is a good start, but it does not find everything; further down you read why.
Preparation
- Disconnect all external devices except keyboard, mouse, display and the charger.
- Put the MacBook on a hard, flat surface with good ventilation.
- Shut the Mac down.
On a Mac with an Apple chip
- Hold the power button as the Mac starts up.
- Release it when you see the startup options.
- Press Command + D.
- The test starts. It takes a few minutes.
On an Intel Mac
- Turn the Mac on and immediately hold the D key.
- Release it when you see a progress bar or a language choice.
- If that does not work, try Option + D: then the test starts over the internet.
Reading the result
After the test you see "No issues found" or one or more messages with a reference code. Write the codes down or take a photo. Apple's support site explains what each code means. A code starting with PPT, for example, concerns the battery. You can repeat the test with Command + R, or restart the Mac with R.
What does Apple Diagnostics test and not test?
- It does: memory, power and charging, the battery, sensors, fans and part of the components on the logic board.
- Not or only partly: a screen with patches or lines, a faltering keyboard or trackpad, problems that only occur sometimes, liquid damage that has not yet caused failures, and software problems.
So "No issues found" does not always mean nothing is wrong.
When is the test useful?
- Your Mac shuts off or restarts by itself.
- The fan keeps running loudly.
- Your MacBook charges poorly or the battery drains fast.
- You are unsure whether to buy a used MacBook. See buying a refurbished MacBook.
Tips for catching problems that do not always occur
If a problem only happens now and then, run the test shortly after it occurred, while the MacBook is still warm. Repeat it a few times. Also note when the problem occurs: while charging, under heavy work, after opening the lid. That information helps us more than a single test result.
The test does not start
If it does not work, charge the MacBook first and try again. If you use a separate wireless keyboard, use the built-in or a wired keyboard. If the Mac does not start at all, read MacBook will not start up.
What do you do with an error code?
Look the code up on Apple's site and note it. Bring it when you have your MacBook repaired: it helps find the cause. With an error code, make a backup straight away in any case, especially if it concerns the storage or memory. See backing up.
What we do at Blue Apple in Amsterdam
We go further than Apple Diagnostics: with our own equipment we measure current, temperature and the components on the logic board, and look for liquid damage under the microscope. That way we also find problems the built-in test misses. You hear beforehand what is wrong and what it costs. More on our page about MacBook repair in Amsterdam.
Frequently asked questions
Does Apple Diagnostics erase my files?
No, it is only a test. Nothing is changed.
How long does the test take?
Usually a few minutes.
Is Apple Hardware Test the same?
That was the name on Macs from before 2013. It works roughly the same way.
