Apple diagnostics

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How to run diagnostics on a Mac with ease

We associate a Mac with quality, capacity, speed, and reliability. But it might happen so that your Mac underperforms and unpredictable issues occur. Before taking it to the nearest Apple service, you can try to identify the problem by yourself. That will save your time and money, and prevent serious system crashes. Identifying whether the issue is a hardware or software one will determine the possible actions and next steps. 

When we deal with the hardware problem, the first thing to try is to perform Apple Diagnostics (or Apple Hardware Test). It will help you reveal the process that causes the problem and lowers Mac productivity.

Apple Diagnostics is an easy-to-understand tool that provides detailed results and suggestions with the next steps. Whether you are a techie or not, you'll get everything easily.

What is Apple Diagnostics?

Apple Diagnostics is a built-in test that helps detect what hardware components are causing the problem, and find system failures. The test checks RAM, power controller, logic board, battery, and other wireless modules.

That was the hard part. And the easy part is that you can run Apple Diagnostics in just a few steps. The whole process will take about  2-5 minutes —  but ultimately saves  hours of your time. 

A great feature of Apple test is that after hardware checking, it displays an error code, offers you clear solutions, and the assistance of Apple Support. You can write out the error codes (known as reference codes), and either do the research on/ your own or contact Apple.

When referring to Mac hardware test, you might also hear about Apple Hardware Test (AHT). This is an older brother of Apple Diagnostics (AD), and they have some minor differences. Mainly, the results of AHT aren't conclusive and descriptive. AHT is used in Macs released in  2012 or earlier, while AD is a more advanced analog that works with newer Macs. 

Essentially, a Mac hardware test is the great tool to help you understand the problem. And if it doesn't have a fix for it — there are more advanced tools that you can use to troubleshoot Mac issues. More about that in a moment.

How to run Mac diagnostics

Running a hardware test on Mac may seem like a complicated process, but believe us — that's not:

  1. Disconnect all the peripheral devices (printer, cables, external DVD drive) except the keyboard, mouse, display, and speakers. Make sure your Mac is connected to mains power and the internet. 
  2. Select Apple Menu > Restart
  3. Press and hold the D key until you see a list of different languages on the screen
  4. Select a language. Apple Diagnostics starts automatically.
  5. Wait for about 2-5 minutes until the checking is completed. If any problems are found, you'll see the options of solutions and an error code. 

Mac diagnostics

After that, you can either repeat the test, get more information, restart or shut down the Mac. That's it - an easy 5-step process, as promised.

Apple recommends to print out the instructions to keep them close at hand and make sure you don't miss any step. Or, you can take a photo. Right, that's what people do in 2021. 

What are the common Apple Diagnostics results

After performing a Mac hardware test, you'll get the list of found issues with detailed descriptions and related reference codes. Each code stands for a particular error and helps you quickly figure out the next steps. Usually, an error description will suggest possible solutions. However, to fix a specific problem, Apple Diagnostics might recommend you to contact Apple or take your Mac to an Apple Authorised Service Provider or AppleRetailStore.

There could be the case the system testing doesn't find any issues. 

In this case, you have a few options. Please note that they are mutually exclusive, which means you should choose the best option for you:

  1.  Repeat the process by hitting Run the test again
  2. Because well, sometimes a small mistake might hamper it all. Maybe the first time you tried to run Apple Diagnostics, your power adapter wasn't plugged in. Connect it and try again — this will help fix the problem.

  3. To get more information on support and service options, click on Get started:
    • The macOS X recovery will start
    • Send your serial number and reference codes to Apple by clicking Agree to send
    • Follow the on-screen instructions.
  4. Restart your Mac 
  5. Hit the Shut Down button.

What if you can't run diagnostics

You can face the problem when Apple Diagnostics simply doesn't work. Don't worry, it's solvable. There might be a couple of reasons why this happens:

  1. Some external devices are plugged in. Double-check you've disconnected everything except the keyboard, mouse, display, and speakers. 
  2. A part of the diagnostics system can be damaged. You can solve the problem by restarting the Mac while holding down Option+D. This will start an internet-based hardware test.
  3. Firmware password might be the problem. Make sure you turn it off while performing hardware testing.

What if diagnostics found no issues

In case Apple Diagnostics identifies no hardware issues —  but your Mac is still misbehaving —  maybe, software is the problem.

Often, Macs are slowing down, freezing, or behaving strangely due to full storage, malware, leftovers from uninstalled apps, large and old files. The good news is you don't have to guess, or install many applications to fix each problem separately. An all-in-one tool called CleanMyMac X has all the required functions to test your Mac from a to z. It cleans up, protects, and speeds up your Mac.

Just one click to optimize your Mac — CleanMyMac X makes it fly like a rocket.

Here's how CleanMyMac X optimization works:

  1. Go to the Maintenance tab
  2. Specify what should be done. For example, if you want to speed up your Mac by freeing up some space, check the box next to  Free Up Ram”. You can select all the tasks at a time, or choose the particular ones. 
  3. Press Run.

CleanMyMac freeup RAM

Yay, you launched a rocket!

The most common problem that impairs system performance is the junk files that clutter your Mac. You might not even know about them. Luckily, CleanMyMac X has a solution for this, too. Resolve various errors with a great feature called System Junk:

  1. Hit Scan
  2. Once you see the results, press Review Details

CleanMyMac system junk

You'll see the list of all items that should be cleaned or fixed. You can review the results  and deselect those items you're not ready to let go. CleanMyMac X will omit them while cleaning up your Mac. Once you're ready, hit Clean.

CleanMyMac user cache files

Wow, your Mac feels much better now.

Know the reason behind Mac issues

Running Apple Diagnostics is a bit like a shot in the dark. You’re trying to fix something you have no idea about. In some cases, it will work, but you can achieve better results if you know why the issues occur. 

iStat Menus is a utility that sits in the menu bar, with tons of useful real-time insights about your Mac. Check your CPU and GPU usage, memory load, fan speeds, and more in one click. Whenever your Mac is freezing, getting slow, or making loud fan noise, iStat Menus will tell you why it happens. 

iStat Menus macOS system monitors

App Tamer is another utility similar to iStat, but with more focus on idle apps hogging your CPU. See which apps are putting pressure on your Mac and force quit or uninstall them to optimize performance. A nice touch: App Tamer changes its menu icon color when CPU use goes beyond normal. 

App Tamer CPU monitor


System performance testing is a handy tool that keeps your Mac healthy, saves your time and money. The primary step is to understand whether the issue is a hardware or software one. While Apple Diagnostics deals with hardware breakdowns, CleanMyMac can fix the software problems.

Doesn't matter if you are a Mac power user or Mac-newbie, these tools will do system testing and optimization for you. To make the most out of your Mac, regularly check its performance with iStat Menus and App Tamer. 

Running Apple Diagnostics and optimizing performance with CleanMyMac X, iStat Menus, and App Tamer prolongs the life of your Mac. These three apps are free for 7 days on Setapp, the curated suite of best productivity apps — so you can try them all to make your Mac fly.


Use Apple Diagnostics on your Mac

Apple Diagnostics is a tool you can use to diagnose problems with your computer’s internal hardware, such as the logic board, memory, and wireless components. You may be able to start your Mac with Apple Diagnostics, even if it doesn’t start using macOS.

To use Apple Diagnostics, follow the instructions in the Apple Support article Use Apple Diagnostics to test your Mac.

  • You may want to print the instructions before you begin. Choose File > Print, then click Print.

  • If Apple Diagnostics reports that your Wi-Fi card is not working properly, contact Apple Support or take your Mac to an Apple Store or Apple Authorized Service Provider.

  • To change the language, press Command-L.

Apple Diagnostics doesn’t check external hardware components, such as USB, or non-Apple devices, such as PCI cards from other vendors. It doesn’t check for operating system (macOS) or software-related problems such as app or extension conflicts.

If a hardware problem isn’t detected, there may be a problem with the version of macOS you’re using and you may need to reinstall it. See Reinstall macOS.

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No matter how well a computer was designed, there will be a time when you’ll experience technical issues, even on a Mac. Fortunately, there’s usually a solution for every problem, and tech issues aren’t any different.

Software problems are easier to deal with. If it’s an issue with macOS, you can always update your Mac and see if Apple’s already fixed the problem for you. The same goes for any app on your Mac. And if everything fails, you can always restart your computer. Simple.

But what about hardware issues? Where do you even begin looking for an issue if you can’t just open up your Mac? Plus, if you’re not that tech-savvy, it might be overwhelming..

Fortunately, Apple has already thought about this. And if you’re having hardware problems, you can always try to find the issue yourself by using Apple Diagnostics.

What Is Apple Diagnostics?

Apple Diagnostics is a feature that lets you scan your Mac for faulty hardware. This test will show you all of the hardware pieces inside your Mac that might have issues and will give you the information you need to understand the problem and fix it.

Note that Apple Diagnostics is a feature that was integrated into every Mac model after June 2013. Older Mac models run a similar program called Apple Hardware Test (AHT). The AHT works similar to Apple Diagnostics, and it should give you the same information you need to fix your hardware issues.

Before You Begin:

Apple Diagnostics is pretty straightforward to use, but you’ll need to do a few things first.

  1. First, make sure your Mac is on a hard flat surface with good ventilation.
  2. Turn off your Mac.
  3. Disconnect all external devices except for the keyboard, mouse, ethernet connection, if you have one, and the power connection.
  4. Turn off any firmware passwords your Mac is using.

With that out of the way, here’s how you can use Apple Diagnostics.

How to Use Apple Diagnostics

How you use Apple Diagnostics will depend on which Mac you’re using. If you have a Mac computer with an Intel Processor, here’s what you need to do:

  1. Press the Power button on your Mac to turn it on.
  2. Immediately after, press and hold the D key on your keyboard. (If just pressing the D key doesn’t work, try pressing and holding the Option key + D.)
  3. Release the D key until you see a progress bar, a small globe, and a message that says your Mac is searching for an internet connection, or it asks you to choose a language.

If you have an M1 Mac, follow these steps:

  1. Turn on your Mac and keep pressing and holding the Power Button while your Mac starts.
  2. When you see startup options release the Power Button.
  3. Press the Command Key ()+ D.

What Happens Next?

Once you’re into the Apple Diagnostics screen, your Mac will ask you if you want to share your Mac’s information with Apple. You’ll be sharing device identifiers, hardware and software specifications, and usage information.

If you agree, you’ll grant Apple access to collect, retain, and maybe use this information.

If you don’t want to share this information, you can click on the option Run offline.

Afterward, your Mac will start scanning itself to find any hardware issues. This will take a few minutes, and once it’s done, you’ll see a list of the possible pieces of hardware that are causing issues. If nothing’s wrong, you’ll see a message saying there were no issues found.

Along with the hardware that’s having issues, you’ll see some additional Reference Codes that you can write down. These codes are meant to give you more information about the problem.

Once you’ve found the information you need, you can either rerun the test, restart your Mac or turn it off. You’ll also see a For more information section that you can click on to find out more about your Mac’s issues. This will boot your Mac in Recovery Mode and open your browser to give you more information. 

What to Do If Your Mac Finds Issues

If your Mac’s results show that you have some faulty hardware, the reference codes from the results will help you fix the issue.

You can use these codes to find more about the issue, as well as possible solutions to the problem. To find out more about your codes, go to the Apple Diagnostics reference codes web page.

The list of codes tells you what the problem is and possible solutions. You can also contact Apple to let its technical support help you out.

Read Next:Best Apple Deals | AirPods Max $100 OFF, MagSafe Battery Pack $15 OFF, iPad Pro $100 OFF (+ Many More)

How to run Apple Diagnostic on a Mac from Mid 2013 and newer

Use Apple Diagnostics to Troubleshoot Your Mac

In 2013, Apple changed its testing software for its Mac lineup. Abandoning the older Apple Hardware Test (AHT) and AHT over the Internet, Apple moved on to Apple Diagnostics to help users find out what might be wrong with their Macs.

Although the name has changed to Apple Diagnostics (AD), the purpose of the app has not. AD can be used to find problems with your Mac's hardware, including bad ​RAM, issues with your power supply, battery or power adapter, failed sensors, graphics problems, issues with the logic board or CPU, wired and wireless Ethernet problems, internal drives, bad fans, camera, USB, and Bluetooth.

Apple Diagnostics Availability

Apple Diagnostics is included on every 2013 or later Mac. It's installed on the original startup drive and invoked using a ​keyboard shortcut when booting up the Mac.

AD is also available as a special boot environment that is downloaded over the internet from Apple's servers. Known as "Apple Diagnostics over the Internet," this version can be used if you replaced or reformatted the original startup drive, which erases the AD version that was included at the time of purchase.

The two forms of AD are, for all purposes, identical. Although, AD over the internet involves a few extra steps to launch and use.

Using Apple Diagnostics

AD is for Mac models from 2013 and later. If your Mac is an earlier model, follow the previously mentioned Apple Hardware Test or AHT over the Internet.

  1. Disconnect any external devices connected to your Mac, including printers, external hard drives, scanners, iPhones, iPods, and iPads. All peripherals except the keyboard, monitor, wired Ethernet (if that is your primary connection to your network), and mouse should be disconnected from your Mac.

  2. Write down the name of the wireless network and the password you use to access it if you use a Wi-Fi connection to the internet.

  3. Shut down your Mac. If you're unable to shut down using the normal shutdown command under the Apple menu, press and hold the Power button until your Mac turns off.

After your Mac turns off, you're ready to start Apple Diagnostics or Apple Diagnostics over the Internet. The difference between the two is the keyboard command you use at startup and the need for an internet connection to run AD over the Internet.

If you have AD on your Mac, that's the preferred version of the test to run. It doesn't require an internet connection. Still, if you have one, you can access the Apple help system, which includes diagnostics notes based on AD error codes that may be generated.

Starting the Test

Here's what you need to do to run the Apple Diagnostics test:

  1. Press your Mac's Power button.

  2. Immediately hold down the D key (AD) or Option+D keys (AD over the Internet).

  3. Continue to hold down the key(s) until you see your Mac's gray screen change to Apple Diagnostics.

  4. If you use a wireless connection, enter the information you wrote down earlier to connect to your Wi-Fi network.

  5. Wait. Apple Diagnostics displays a Checking Your Mac message, along with a progress bar. AD takes 2 to 5 minutes to complete.

  6. AD displays a brief description of any issues uncovered, along with a corresponding error code. Write down any error codes that are generated and compare them with the error code table below.

Finishing Up

If your Mac generated errors during the AD test, you can send the codes to Apple, which will result in an Apple support page that shows options for repairing or servicing your Mac.

  1. Click the Get Started link to continue to the Apple support site.

  2. Your Mac restarts using macOS or OS X Recovery, and Safari opens to the Apple Service & Support web page.

  3. Click the Agree to Send link to send the AD error codes to Apple (no other data is sent).

  4. View the additional information about the error codes that the Apple Service & Support page shows and the options you can take to resolve the problems.

  5. If you would rather shut down or restart your Mac, press S (Shut Down) or R (Restart). If you want to rerun the test, press the Command+R keys.

Apple Diagnostics Error Codes

Compare any error codes that resulted from running Apple Diagnostics with this list:

Error CodeDescription
ADP000No issues found
CNW001 - CNW006Wi-Fi hardware problems
CNW007- CNW008No Wi-Fi hardware detected
NDC001 - NDC006Camera issues
NDD001USB hardware issues
NDK001 - NDK004Keyboard issues
NDL001Bluetooth hardware issues
NDR001 - NDR004Trackpad problems
NDT001 - NDT006Thunderbolt hardware problems
NNN001No serial number detected
PFM001 - PFM007System Management Controller problems
PFR001Mac firmware issue
PPF001 - PPF004Fan problem
PPM001Memory module issue
PPM002 - PPM015Onboard memory problem
PPP001 - PPP003Power adapter issue
PPP007Power adapter not tested
PPR001Processor problem
PPT001Battery not detected
PPT002 - PPT003Battery needs to be replaced soon
PPT004Battery requires service
PPT005Battery not installed correctly
PPT006Battery requires service
PPT007Battery needs to be replaced soon
VDC001 - VDC007SD Card reader issues
VDH002 - VDH004Storage device issue
VDH005Can't start OS X Recovery
VFD001 - VFD005Display issues encountered
VFD006Graphics processor problems
VFD007Display issues encountered
VFF001Audio hardware problems

It's possible that the AD test won't find any issues, even though you're having problems you believe are related to your Mac's hardware. The AD test is not a complete and comprehensive test, although it will find most of the common issues associated with hardware. If you still have problems, don’t rule out such common causes as failing drives or software issues.

Thanks for letting us know!


Diagnostics apple

Use Apple Diagnostics to test your Mac

Apple Diagnostics, formerly known as Apple Hardware Test, can check your Mac for hardware issues.

If you think your Mac might have a hardware issue, you can use Apple Diagnostics to help determine which hardware component might be at fault. Apple Diagnostics also suggests solutions and helps you contact Apple Support for assistance.

Prepare your Mac

  1. Shut down your Mac.
  2. Disconnect all external devices except keyboard, mouse, display, Ethernet connection (if applicable), and connection to AC power.
  3. Make sure that your Mac is on a hard, flat, stable surface with good ventilation.

Start Apple Diagnostics

Apple silicon

  1. Turn on your Mac and continue to press and hold the power button as your Mac starts up.
  2. Release when you see the startup options window, which includes a gear icon labeled Options.
  3. Press Command (⌘)-D on your keyboard.

Intel processor

  1. Turn on your Mac, then immediately press and hold the D key on your keyboard as your Mac starts up. 
  2. Release when you see a progress bar or you're asked to choose a language.

View the test results

Apple Diagnostics shows a progress bar while it's checking your Mac:

macOS Diagnostics running progress bar

When testing is complete, Apple Diagnostics shows the results, including one or more reference codes. Learn about Apple Diagnostics reference codes.

macOS Diagnostics results. No issues found.

To repeat the test, click “Run the test again” or press Command-R.

To restart your Mac, click Restart or press R.

To shut down, click Shut Down or press S. 

To get information about your service and support options, make sure that your Mac is connected to the internet, then click ”Get started” or press Command-G. Your Mac will restart to a webpage with more information. When you're done, choose Restart or Shut Down from the Apple menu.

Learn more

On an Intel-based Mac, if you can't start Apple Diagnostics with the D key, try these solutions:

  • Press and hold Option-D at startup to use Apple Diagnostics over the internet.
  • Make sure that your Mac isn't using a firmware password.

Published Date: 

Create Apple Hardware Test on USB flash drive (confirmed working)

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