How to run diagnostics on Mac [Plus, extra tools to test it]

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 yourself by running comprehensive MacBook diagnostics — Apple Diagnostics, to be precise. It will save you time and money and prevent serious system crashes. In this article, you will learn how to run diagnostics on Mac and how to interpret the results.

What is an Apple Diagnostics?

Apple Diagnostics is a built-in test that helps determine which hardware components are causing the problem and pinpoint system failures. The test checks the 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 takes about 2-5 minutes but ultimately saves hours of time. 

A great feature of Apple Diagnostics is that after it checks your hardware, it displays an error code and provides you with clear solutions and assistance from Apple Support. You can write down the error codes (known as reference codes) and either do the research yourself or contact Apple.

When should you run diagnostics on Mac?

If you think there's a hardware problem with your Mac — which could be the case if your Mac shuts down randomly, runs extremely slowly, etc. — you should consider an Apple Diagnostics Mac test. 

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

Let me start with a quick overview.

What happened?	This may help!
You need to run diagnostics on an Apple Silicon (M1/M2) Mac.	Disconnect all non-essential devices > Shut down Mac > Press and hold the power button > Press and hold Command + D when you see startup options.
You need to run diagnostics on an Intel-based Mac.	Disconnect non-essential devices > Shut down Mac > Press power button > Immediately press and hold the D key.
Apple Diagnostics returns an error code.	Research the solution in the list of reference codes.
You need to know the true capacity of your Mac.	Run a series of tests (benchmark, stress, bottleneck) with Novabech.
Apple Diagnostics finds no issues, but your Mac still underperforms.	Run a software cleanup with CleanMyMac.
Apple Diagnostics won’t run.	Disconnect all unnecessary devices, try running diagnostics by pressing Option + D, or disable the firmware password.
Your Mac won’t turn on, and you need to run diagnostics.	Try pressing power button and then holding down the D key (or Command + D).
You want to monitor your Mac’s performance continuously.	Use iStat Menus.

How to run a diagnostic on M1&M2 Mac (Apple Silicon chip)?

If you are interested in running diagnostics on Mac with the Silicon chip, follow these steps:

1. Disconnect all the devices from your Mac except for the essentials, such as a keyboard, monitor, mouse, etc.
2. Shut down your computer in case it was turned on.
3. Start your Mac as usual by pressing and holding the Power button until you see the startup options.
4. Press Command + D  to run the Diagnostics test on your Mac.

How to run a diagnostic on Mac with Intel Processor?

Now, I'll show you how to run Apple diagnostics on Intel-based Macs.

1. Disconnect all unnecessary devices (much like with the Apple Silicon Mac). 
2.  Shut down your Mac.
3. Press Power button and hold the D button right away.
4. Release the buttons when you see a selection of languages.
5. Choose the necessary language, and the diagnostics process will start.

Run your Mac diagnostics with ease

Apple Diagnostics is not the only way to diagnose your Mac. I'll suggest four other tools that check other parts of the Mac or do it in a different, more advanced way. 

#1. To benchmark your Mac's performance — Novabench

While Apple Diagnostics identifies problems, Novabech runs a series of tests — benchmark, stress and bottleneck tests. The result is not just numbers. It's a handy explanation in plain English that helps you understand two things. 

The first is how well (or not) your Mac performs compared to the baseline. The second is how your Mac compares to hundreds of other Macs that have undergone similar tests. Here's an example of what your results might look like:

The benchmark results will help you understand what you can do to improve your Mac's performance. For example, you might want to know how to clear system storage on Mac, how to free up RAM on your Mac, or how to fix an overheating Mac.

#2. To run a deep scan and clean your Mac — CleanMyMac

Sometimes you search for how to diagnose your Mac after you have already experienced certain problems with the system. This is similar to many people who only go to the doctor when something starts hurting badly.

It is always better to get regular checkups and prevent health problems, and the same goes for computers. I recommend monitoring and cleaning your Mac on a regular basis, and apps like CleanMyMac are incredibly helpful.

The tool offers a range of options, such as speeding up your computer, disk cleanup, uninstalling unnecessary and broken apps, etc.

Many so-called junk files tend to accumulate on your computer, and cleaning them manually either takes a lot of time or requires special knowledge to discover their location. With CleanMyMac, you can perform regular cleanups with just a few clicks. It is also possible to search for specific types of files if you want to get rid of something particular.

#3. To monitor your Mac's health 24/7 — iStat Menus

Another app you might find useful in this situation is iStat Menus. It helps with monitoring various stats and providing feedback on the performance of your Mac. You will get info about the memory, temperatures of different parts of your computer, disk performance, and more. 

You can display all this data in different kinds of charts for easier comprehension. It is also possible to turn on the specific features you need, which you will see in the menu bar. With all these stats at your disposal, you can always monitor the performance of your device easily and take action anytime certain issues occur.

#4. To have key performance data at your fingertips — Usage

If complicated graphs with numerous indicators aren’t your thing, I recommend a simple tool: Usage. It tracks key metrics and, based on my observations, here are the approximate thresholds you should avoid exceeding:

• Disk load: 70-80%
• Processor load: 60%
• Memory load: 80%

Your Mac will perform better if these numbers are lower, but these are realistic limits if you’re running heavy apps or multiple programs at once.

What are the common Apple Diagnostics results?

Now, let's get back to Apple Diagnostics. After performing Mac hardware diagnostics, 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 contact Apple or take your Mac to an Apple Authorized Service Provider or Apple Store.

What if you can't run diagnostics?

In some cases, Mac users might experience issues with running Apple Diagnostics in the first place. Here are some things you can do to solve this problem:

• Disconnect all other devices. You might have forgotten to disconnect some devices other than essentials (you don't need to disconnect your mouse, computer screen, and keyboard). The power source and the internet need to be connected as well, but all the other tech should be disconnected.
• Test hardware. The diagnostic system can also malfunction. You can initiate another test that requires an internet connection by pressing and holding Option + D at the same time.
• Disable firmware password. This might be the issue that interferes with diagnosing your Mac.

What if diagnostics found no issues?

Sometimes, there are no issues with your hardware even when the computer seems to have performance issues. In this scenario, the problem might be in your software. The storage might be full, tons of unnecessary and broken files might clutter the system, etc. In this case, we recommend you do a cleanup scan with the help of CleanMyMac.

This is how you can clean up space on your computer:

1. Install and open CleanMyMac.
2. In the left sidebar, click Smart Scan.
3. Perform a scan to discover the files you want to get rid of. CleanMyMac offers deleting various system junk and mail files or even cleaning up your trash bins. Pick the necessary option and click on the Clean button.
4. Wait for the app to delete unwanted files.

   

This is only one way of optimizing your Mac by using CleanMyMac's features. One of the biggest issues that usually slow down the performance of your Mac is crowded memory. Fortunately, there is an easy way to free up some space. To do that quickly, follow the steps below.

1. Install and open CleanMyMac on your Mac.
2. In the left sidebar, click Maintenance.
3. 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 once or select only the particular ones.
4. Click on the Run button and wait for the app to clean up some space on your Mac.

After these cleanups, you'll feel the difference in how your computer performs. However, there are also other ways to improve things even further.

Excessive CPU (central processing unit) use is among the things that often slow down computers. Of course, when the CPU is occupied, the performance can drop noticeably. Different background programs can use the CPU a lot, and it is often difficult or even impossible to slow them down or turn them off manually. Luckily, there is a great app for this.

App Tamer allows finding idle programs on your device that occupy too much CPU and hinder the performance of your Mac. All you need to do is to turn on the App Tamer and see which programs cause you all this trouble. It is possible to turn them off completely or adjust the amount of CPU they are using. These features not only help with improving Mac's performance but also make the battery life longer and prevent the computer from overheating. This is incredibly helpful in the long run as well, as you will not need to troubleshoot your computer as much.

The best way of running diagnostics on Mac

The system diagnostic Mac feature may keep your Mac healthy and save you time and money. When testing your device, the primary step is to understand whether the issue is a hardware or software one. While Apple Diagnostics deals with hardware breakdowns, CleanMyMac, App Tamer, and Novabech can fix software problems.

Running Apple Diagnostics and optimizing performance with third-party apps prolongs the life of your Mac. These apps are free for 7 days on Setapp, a platform with over 240 curated apps for Mac and iOS in every category you can imagine. Try any Setapp app at no cost today and find new favorites to add to your app stack.

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