How to fix horizontal or vertical lines on MacBook screen

Imagine starting your Mac and seeing horizontal or vertical lines on the screen. You would feel alarmed, right?

Don’t be. Even though it might look bad, it doesn’t necessarily mean that the problem is that serious. Yes, it could be a complex hardware issue that only Apple Genius or an authorized Apple service provider can fix. But it can also be a simple software issue that you can quickly fix yourself. We’ll cover the most likely causes and how to fix them in this article.

Why is there a line on my MacBook screen?

Hardware issues could cause the lines. Such cases can include:

• Damaged screen possibly caused by the MacBook being dropped
• Overheating
• Screen burn-in. It usually happens when an LCD screen displays the same image for a long time. However, it’s unlikely to result in horizontal lines on your MacBook screen or vertical lines.
• The cable connecting the graphics chipset to the screen is damaged.

Software issues could also be the cause of this problem. These include:

• Power management issues
• Outdated graphics drivers
• Software conflicts

All of these reasons apply to iMac as well as Mac mini, Mac Pro, or Mac Studio screen. For Macs with screen, though,  the problem could also be caused by the external display or cable connecting the computer to the display, the socket on your Mac, the monitor, or issues with the external graphics card.

How to fix lines on your Mac’s screen

Before making an appointment with Apple Genius, try fixing lines on your Mac’s screen yourself. To help you with that, we’ve made a list of easy-to-follow tips for you to check out.

1. Restart your Mac

Have you tried this already? If not, do it. Restarting your Mac may be the easiest fix to solve such problems.

2. Run maintenance scripts

Maintenance scripts usually run automatically on your Mac and clean up things like system logs and temporary files. However, there is a high probability that they do not run as often as they should. Running them by hand may fix the problem of lines on your screen — only if it’s a software problem causing it.

The easiest way to run maintenance scripts is to use an app designed for the job. CleanMyMac X is such a tool. It has many modules to keep your Mac junk-free, including a dedicated Maintenance module. The last one allows you to run these scripts with a single click. Download CleanMyMac X for free here.

3. Check the connection

If the display showing lines on the screen is an external monitor, ensure the cable is connected securely at both ends. You can also try a different cable if you have one. It could be the faulty cable causing this.

4. Try different display

If you’re using an external monitor and have another display at hand, try plugging it in. Also, you can try using a different port to see if that will work for you. For example, if you were using DisplayPort, switch to HDMI.

But in case you’re not using an external display, meaning the problem is with your Mac’s built-in screen, try connecting it to an external monitor. If the glitching persists, you know it’s not your computer’s screen that is faulty. Similarly, if the problem goes away, you know it’s a hardware problem that requires a tech professional to fix.

5. Check your Mac’s temperature

Sometimes, the lines on the screen may appear because of your Mac overheating. That is why if the temperature in the room you’re in is too high or you hear Mac’s fans blowing hard, shut it down and let it cool for a while before booting it back up.

Before shutting your Mac down, you may want to know its temperature. In this case, the focus is on the CPU, and the temperature goes up because of running resource-hungry apps. The normal range is between 45 and 66 degrees Celcius, but how do you measure it?

The easiest way to check Mac’s temperature is to use a trustworthy third-party app, and we recommend CleanMyMac X. Its Menu app comes with a CPU monitor that includes the tool for checking the temperature. To access it, click on a little iMac icon in the menu bar and open the CPU tab. 

Download CleanMyMac X for free here if you haven’t done it yet. 

There are, of course, other third-party apps you can use, but ensure that the developer is trustworthy before downloading anything to your Mac.

6. Reset the SMC

The system management controller (SMC) handles the power management on your Mac at the startup. So, if it is a power issue causing the lines on your Mac’s screen, resetting the SMC may repair it.

Are you a lucky owner of a Mac with an Apple silicon (M) chip? Then, you have the option to reset the SMC by simply restarting your Mac while it’s plugged in. For Intel-based Macs, the process involves a few more steps and differs depending on whether your Mac has a T2 security chip or not. It’s also different for laptops like MacBook Pro or MacBook Air and PCs like the iMac.

Check out Apple’s comprehensive instructions on resetting the SMC on Intel-based Macs here.

Seeing horizontal or vertical lines on MacBook screen doesn’t necessarily mean something is seriously wrong. Try the quick fixes outlined in this article first to resolve the issue. If those won’t work, contact the expert at Apple Genius Bar or another authorized service center for external assistance. Make an appointment ASAP and get to enjoy your perfectly functioning Mac again.