Mac (Sequoia) Not Recognizing External Monitor [Fixed]

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When it comes to portability and durability, the MacBook Air and MacBook Pro are often top choices. However, with screen sizes ranging from only 13 to 16 inches, many users choose to connect a second, larger monitor for both professional tasks and entertainment. Setting up a separate display on a MacBook is straightforward: simply connect the external monitor to your Mac using the appropriate port and cable.

But sometimes, things don't go as planned. If your Mac isn't detecting your external monitor, especially after the macOS Sequoia update, don't worry. After identifying the possible causes, we have gathered 6 proven solutions to help resolve this unrecognized external monitor issue.

Let's go.

Why Is My External Monitor Not Detected on macOS Sequoia?

Understanding what may have caused the external monitor not detected by MacBook can help you quickly find the right solution. If you're unsure what's causing the problem, here are some common reasons for Mac external monitor issues.

• Temporary system glitches
• Incompatible cable or adapter
• Loose connection
• Incorrect display settings
• Outdated macOS
• Hardware issues with the ports or display

How to Fix External Monitor Not Working on Mac (Sequoia)

Resolving the issue of a second monitor not working on a Mac involves addressing both hardware and software problems. You may have attempted some of these solutions already, but reviewing them here ensures you can try them again using this guide, in case you overlooked any key details.

Fix 1. Restart your Mac

Occasionally, your Mac may experience glitches that prevent it from immediately recognizing connected external devices. Apple suggests putting your Mac to sleep and then waking it up. Alternatively, restarting the system can also prompt it to detect external devices including another monitor.

You can restart your Mac by clicking the Apple logo and selecting Restart. You can also choose to force a restart by holding down the power button or the Touch ID button for 5 seconds, then pressing the same button once to turn your Mac back on.

Fix 2. Make sure the cable connection is secure

Since your external display is connected to your MacBook with a wired cable, it's important to ensure the connection is secure. Try unplugging the cable and plugging it back in, ensuring that both your Mac and the display are firmly connected.

Fix 3. Check if you are using the correct cable, port, or adapter

First, check that your cable is compatible with both your Mac and the monitor. Macs often require specific types of cables, such as USB-C, Thunderbolt, HDMI, or DisplayPort, so verify that your cable matches the ports on both devices.

Here is how to check the supported cable by Mac:

Step 1. Choose from the Apple menu and select System Settings.

Step 2. Click Help from the top menu bar.

Step 3. Choose [Your Mac Model] Specifications such as MacBook Pro Specifications.

Step 4. Scroll down to Display Support or Video Support.

If you have a MacBook Air, an external monitor is typically connected through a USB-C or Thunderbolt port. For a MacBook Pro, it's more common to connect an external display via the HDMI port. If one port type doesn't work, try a different one. In such cases, you might need an adapter or dock, so ensure you are using the correct adapters for your setup.

Fix 4. Adjust the display settings

If your Mac doesn't detect an external monitor, you can manually force it to scan for the connected display in the system settings. This technique is useful for the external monitor not working after the Sequoia update.

Step 1. Choose Apple menu > System Settings.

Step 2. Go to the Displays option in the sidebar.

Step 3. Press and hold the Option key to unhide the Detect Displays button in place of the Night Shift button.

Step 4. Click Detect Displays to help your Mac recognize the connected external monitor.

Fix 5. Check for any signs of hardware damage

If the external screen suddenly stops working, you should carefully inspect the ports on your Mac and monitor for any physical damage, as deformed ports can affect the external display connection. Also, check for debris in the ports, and clean them and the connectors with a clean, dry cloth.

If you have another computer, try connecting the display to it. If the display still doesn’t work, it may be faulty.

Fix 6. Update the macOS

If your external monitor remains undetected by your Mac laptop after trying all the methods above, performing a software update is another option. Ensuring your Mac is running the latest version of macOS may resolve any system issues causing the monitor detection problem.

Here is how to update the macOS:

Step 1. Go to the Apple menu > System Settings.

Step 2. Select General > Software Update.

Step 3. If there is an available update, click Update Now or Upgrade Now.

Improve Your Mac's Performance for Faster External Display Detection

When your Mac runs slowly due to reduced computing power, it can struggle to recognize external devices. This may lead to delays or failure in detecting an external monitor. Closing unnecessary applications, managing startup items, and freeing up storage can help improve detection speed and efficiency.

BuhoCleaner is designed for these purposes. This comprehensive Mac cleaner app helps optimize your storage and boost your Mac's overall performance. As a result, it can enhance the speed and success rate of your Mac when detecting an external monitor.

Key features:

• Remove large files, duplicate files, and junk files to free up Mac storage
• Completely uninstall applications that may conflict with the external screen
• Free up RAM to release more memory for external monitor detection
• Manage startup and login items for faster external display recognition
• Monitor system status in real time from the menu bar

Conclusion

If you plug an external display into your Mac and nothing happens, this article provides 6 ways to address the Mac (Sequoia) external display recognition failure. You can start by restarting your Mac, followed by checking the connection, cable, port, and adapters. If everything seems fine, try to adjust the display settings and make sure your macOS is up-to-date.

After fixing the issue with your Mac not detecting an external monitor, install BuhoCleaner to enhance your Mac's performance and speed up the recognition of connected displays.