How to Run Diagnostic on Mac: A Complete Guide

Running a diagnostic on your Mac can help you identify issues and solve problems related to your device’s performance. Macs are built to endure rigorous use, but just like any other piece of technology, they can experience glitches or malfunctions. If you’re experiencing slow application launch times, startup issues, or any other problems, a diagnostic test can help you identify the root cause of the issue.

To help you run a diagnostic on your Mac, we’ve compiled a comprehensive guide in 12 easy-to-follow steps. By the end of this article, you’ll be equipped with the knowledge and skillset to troubleshoot and fix any issues that may arise on your device.


Step 1: Check Free Storage Space

One of the first and easiest things you should do when running a diagnostic on your Mac is checking the free storage space. You can check the amount of free space on your device by clicking the Apple menu, selecting “About This Mac,” and then navigating to the “Storage” tab. If you have less than 10% of the storage space available, you should consider clearing some data. You can also use the Disk Utility application to check the health and integrity of your hard drive.

Step 2: Boot in Safe Mode

Boot your Mac in Safe Mode to see if the issue persists. This mode will only load essential files and software, so you can see if it’s a software or hardware issue. To boot in Safe Mode, shut down your Mac, press and hold the Shift key, and then power your computer back on.

Step 3: Run First Aid in Disk Utility

Use Disk Utility’s First Aid feature to verify and fix any issues with your hard drive. This feature will scan your device for errors and repair them if necessary. You can access the First Aid feature by opening Disk Utility, selecting the volume you want to scan, and clicking the First Aid button.

Step 4: Run Apple Hardware Test

The Apple Hardware Test is a comprehensive test suite that can help you identify any hardware issues with your Mac. To access this test, hold the D key while your Mac is booting up. From there, follow the on-screen instructions.

Step 5: Reset PRAM and SMC

Resetting the NVRAM or PRAM and SMC can help you solve issues with your device’s system management controller. To reset the PRAM and SMC, shut down your Mac, press and hold the Command, Option, P, and R keys, and then power your computer back on.

Step 6: Repair Disk Permissions

Incorrect permissions can cause issues on your Mac. Use Disk Utility to repair permissions on your hard drive. Open Disk Utility, select the volume you want to repair, and click the “Repair Permissions” button.

Step 7: Use Terminal to Check for Problems

The Terminal application on your Mac can help you identify issues related to software and hardware. Use the Terminal to check for disk errors, run RAM tests, and more.

Step 8: Uninstall Unused Applications

Uninstalling applications you don’t use can help free up space on your device and improve performance. Look for unused applications in your Applications folder and drag them to the Trash.

Step 9: Reinstall macOS

If you can’t identify the issue, consider reinstalling the macOS operating system. Before doing so, you should back up your data. You can reinstall macOS by starting your Mac in Recovery mode and then following the on-screen instructions.

Step 10: Run Third-Party Diagnostic Tools

There are many third-party diagnostic tools available for Macs. These tools can help you identify issues with your device and provide solutions. Some popular diagnostic tools include TechTool Pro, Drive Genius, and DiskWarrior.

Step 11: Contact Apple Support

If you’ve tried all the previous steps and are still experiencing issues, it’s time to contact Apple Support. They’ll be able to help you troubleshoot and identify the issue. You can contact them by visiting their website, calling their support line, or visiting an Apple Store.

Step 12: Schedule a Genius Bar Appointment

If the issue persists, it’s time to schedule a Genius Bar appointment. An Apple technician will be able to help diagnose the issue and provide a solution. You can schedule an appointment by visiting the Apple Store website.


We’ve covered twelve steps to help you run a diagnostic test on your Mac. Each step is designed to help you identify the root cause of the issue and provide a solution. From checking free storage space to scheduling a Genius Bar appointment, these steps will ensure you take all necessary precautions when diagnosing and troubleshooting your device.

Tips and Tricks

Tip 1: Keep your Mac up to date by regularly installing software updates.

Tip 2: Use Time Machine or a similar backup tool to backup your data regularly.

Tip 3: Consider using a third-party maintenance tool like CleanMyMac X to help keep your device optimized and free from potential errors.

Tip 4: Delete temporary files and folders that accumulate over time to free up space on your hard drive.

Tip 5: Use a high-quality cleaning cloth to clean your Mac’s screen and keyboard regularly.

Tip 6: Use Activity Monitor to identify which applications are consuming the most resources on your device.

Tip 7: Use a surge protector to protect your Mac from power surges and fluctuations.

Tip 8: Consider adding more RAM to your device to improve performance.

Tip 9: Use a high-quality antivirus tool to protect against malware and other vulnerabilities.

Tip 10: Disable unnecessary startup programs to improve startup times and reduce clutter on your device.

In conclusion, running a diagnostic test on your Mac is crucial to maintaining its performance and prolonging its lifespan. By following these twelve steps and employing these tips and tricks, you’ll ensure your device stays optimized and free from potential issues.

Advantages and Disadvantages of How to Run Diagnostic on Mac


1. Improved performance: Running diagnostics on your Mac can help identify and fix any issues that may be slowing down your computer.

2. Identifying hardware problems: The diagnostic tool can help pinpoint any hardware malfunctions on your Mac, allowing you to address the problem quickly.

3. Improved reliability: Regularly running diagnostics on your Mac can help prevent potential issues in the future, improving the overall reliability of your device.

4. Saves time and money: Fixing potential problems before they cause major damage can save you both time and money in the long run.

5. Ease of use: Running diagnostic tests on a Mac is relatively easy, with the process being straightforward and simple to follow.

6. Increased lifespan: Taking care of your Mac through regular diagnostic checkups can help prolong its lifespan.

7. Faster problem resolution: The diagnostic tool can identify the root of the problem quickly, allowing for a faster and more efficient resolution.

8. Less frustration: Regularly checking your Mac through diagnostics can reduce the frustration of waiting for it to load or dealing with unexpected shutdowns.

9. Enhances security: Running diagnostics can identify malware or virus-related issues and ensure that your device runs efficiently and securely.

10. Peace of mind: By carrying out regular checks on your Mac, you can have peace of mind that your device is in good working order, and potential problems can be addressed before they cause major damage.


1. False positive results: Sometimes the diagnostic tool can identify potential issues that aren’t actually present, leading to unnecessary repairs or replacements.

2. User error: Running diagnostics requires a level of technical know-how, and if not performed properly, it can lead to further problems.

3. Limited effectiveness: While diagnostics can help identify problems, some issues may be more complex and require a professional to address them.

4. Time-consuming: Depending on the severity of the issue, running diagnostics can take a significant amount of time, which may not be feasible for everyone.

5. No guarantee of fixing all issues: While diagnostics can identify potential problems, it doesn’t guarantee that all issues will be fixed.

6. Only applicable to Mac devices: The diagnostic tool is only usable for Mac computers, limiting its usefulness for those who own other types of devices.

7. Limited availability: The diagnostic tool is only available for newer Mac versions, limiting its usability for older devices.

8. Potential privacy concerns: Some users may have concerns about sharing their data with the diagnostic tool, leading to privacy issues.

9. Requires software updates: For the diagnostic tool to function properly, it requires regular software updates, which may not always be convenient for users.

10. Cost: While the diagnostic tool is free, fixing issues identified through the tool may come with a cost, leading to potential expenses.


1. What is diagnostic mode?

Diagnostic mode is a special mode on your Mac that allows you to diagnose hardware problems and perform other troubleshooting tasks.

2. How do I enter diagnostic mode on my Mac?

Restart your Mac and hold down the D key while it’s starting up. This will launch the Apple Hardware Test, which is the diagnostic mode.

3. What hardware tests does diagnostic mode perform?

Diagnostic mode can run a range of hardware tests, including tests on the CPU, memory, logic board, and more.

4. How long does a diagnostic test take?

The length of time a diagnostic test takes depends on the specific test being run. Some tests can take just a few minutes, while others may take longer.

5. Can I run a diagnostic test while using my Mac?

No, you should always perform a diagnostic test when your Mac is starting up in diagnostic mode, as this ensures the most accurate results.

6. What do I do if a diagnostic test fails?

If a diagnostic test fails, you should contact Apple Support for further assistance.

7. Can I run a diagnostic test on an external hard drive?

Yes, you can connect an external hard drive to your Mac and run a diagnostic test on it. This can be useful for checking the health of the drive.

8. Is there a way to automate diagnostic tests on my Mac?

Yes, there are third-party tools available that can automate diagnostic tests on your Mac. These tools can save you time and ensure your system stays healthy.

9. Can I run a diagnostic test on a non-Mac computer?

No, diagnostic tests are only available on Macs.

10. Why should I perform regular diagnostic tests on my Mac?

Regular diagnostic tests can help detect hardware problems before they become serious, and can improve overall performance and stability.

11. Is diagnostic mode the same as safe mode?

No, diagnostic mode and safe mode are different modes on your Mac. Safe mode is used to troubleshoot software problems, while diagnostic mode is used to diagnose hardware problems.

12. Can I run a diagnostic test on my iOS device?

No, diagnostic tests are only available on Macs and are not available on iOS devices.

13. Can I still use my Mac while a diagnostic test is running?

No, you should not try to use your Mac while a diagnostic test is running, as this can interfere with the test and affect the accuracy of the results.

How to Run Diagnostic on Mac

If you own a Mac, it’s important to know how to run a diagnostic test in case of any issues. Diagnostic tests can help identify problems and provide insight into what needs to be fixed or repaired. In this article, we’ll take a look at how to run a diagnostic test on your Mac.

Conclusion and Closing

Running a diagnostic test on your Mac is easy and can save you time and money in the long run. By following the steps outlined in this article, you can identify potential issues with your Mac and take action before the problem worsens. Remember, regular maintenance and checks can extend the life of your Mac and keep it running smoothly for years to come.

Thank you for reading! We hope this article has been helpful in guiding you through the process of running a diagnostic test on your Mac. If you have any further questions or concerns, don’t hesitate to reach out to customer support or a professional technician. Until next time, take care!