Level 1

80 points

Persistent horizontal lines appear on iMac screen

I am reaching out to share an ongoing issue I, along with several other users, have been experiencing with our iMac 24-inch models, and to seek a collective resolution.

Problem Description:

Persistent horizontal lines appear on the screen, which significantly hampers the usability and visual appeal of the device.
This problem arises without any physical damage, and despite the stationary nature of the device.

Steps Taken:

Connected to an external display: The external display works fine, indicating the issue is with the iMac's internal display.
Reinstalled the OS: The problem persisted post reinstallation.
Avoided operating the iMac for a week: No change in the situation.

Concerns:

The cost of screen replacement is high, and there's no assurance that it will resolve the issue permanently.
The quality concern is alarming especially for a brand that positions itself as a premium segment player.
The support received thus far has been unsatisfactory, with no definitive solutions provided apart from a costly screen replacement suggestion.

Please do not ask us to visit to service center and replace the screen for 650USD + , problem happens mostly after warranty.

[Edited by Moderator]

iMac (M1, 2021)

Posted on Oct 21, 2023 10:40 AM

Top-ranking reply

Limnos

Level 10

427,151 points

Posted on Feb 7, 2024 9:45 AM

To make the best of a bad situation you could always use a separate monitor with the iMac. It's an annoyance given that there's already a display taking up desk space but at least you wouldn't have to get another computer. I kept several older iMacs going that way. Just make sure that if the display is really starting to go that you set this up before it is fully gone. You set up the second display as mirroring the first one and with iMacs this has to be done while you can still navigate the main display.

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512 replies

Oct 30, 2025 12:16 AM in response to Giorgio_BXN

Sad to say Even they offer free repair on the screen, the lines problem will still come back upon using it for one year or so. FYI My is M3 iMac also encounter this flaws beside your M1. In fact I curious on those using M4. I don't feel shock their iMac after using it for one year or so , Lines suddenly appear on their screen. IF that happen means Apple Quality is indeed in Doubt since the flaws start from M1 now continue to M3....

Joe805

Level 1

53 points

Nov 5, 2025 4:02 PM in response to mmzatma

I took another poster's suggestion to write to Tim Cook. I received a reply within a couple of hours from 'Brandi', a rep at Apple. I replied to the email restating my case and received a call today after I missed a VM. I spoke, pleaded, actually, stating my case (and those of the 740+ unique individuals who have posted in this forum or clicked "me too", asking for Apple to take responsibility for their problem causing the damaged screen. I was on the phone for about 24 minutes without result. She said she would set up a (another) call with a senior advisor and advocate for me.

To keep this short, I'm rethinking my 'blind' loyalty to Apple since becoming a customer with the Mac Classic in the early 1990s. I'd like to have a reason to remain a loyal user.

elpathy

Level 1

19 points

Nov 19, 2025 10:07 AM in response to latVm

I am very disappointed with Apple for two reasons:

My 2021 iMac screen started displaying horizontal lines (and flashing) on the bottom half of the screen. Since so many others have also reported this problem, it speaks directly to the deficiency in this Apple product.
I traded it in for a Mac Mini last week. The trade-in value was estimated at $45. Today I got an email saying I had misrepresented the product and the new trade-in value was $0.. That is because I accidentally said that my machine had a 256GB SSD when it actually had a 512GB SSD!!!

This is just addding insult to injury. Apple should be ashamed of themselves.

mfbk67

Level 1

14 points

Dec 1, 2025 9:12 PM in response to latVm

Thanks for all this information which call to Apple Support provided none of when my iMac 2021 suddenly developed flickering horizontal lines on the screen when I turned it back on after shutting it down for a week while I was out of town. I have had it for 4 years sitting on my desk--no damage by me. For what it is worth, I found the "Product Feedback" page on Apple website and sent link to this thread, and wrote this about my defective iMac:

"https://discussions.apple.com/thread/255220596?sortBy=rank

I have joined the hundreds of iMac customers who have been burned by this defect as you will see in above thread. My family own Apple products since the 1980s, both at home and at work, for their quality, reliability and customer accountability. No longer it seems when a 4 year old iMac in pristine condition out of the blue develops flickering horizontal lines on all but the top of the screen. Talk about a headache. Apple's solution: buy a new $600+ screen (same design) with a 90 day warranty! Where is the investigation? Apple acknowledgement/help? The fix? Meanwhile until the hardware glitch is fixed: recalls, free or highly discounted screen/computer replacements. Our loss of $/time/energy/lost productivity is not small."

Only hope is protest of enough customers.

Dec 8, 2025 12:14 PM in response to LizEnserink

Thank you for participating in the Apple Support Community.

We want to make sure you reach the right team for help with your device. We recommend that you contact Apple Support directly. Depending on your region, you may be able to reach them here: Get Support.

Stefy12

Level 1

20 points

Dec 9, 2025 12:21 PM in response to latVm

Monday, December 1st suddenly the same horizontal lines appeared on the display of my iMac 24" M1 (2021).

1) One black fixed horizontal line on the middle of the display

2)During the evening, below this line there is a space of 5/6 cm with normal display and below this all black lines

3)During the day, the black lines reach up to the central black line and some time they are flickering

I'd like to point out that I always kept the display brightness low.

A Senior Advisor confirmed to me that it is a hardware problem and to report to Feedback - iMac - Apple

I am truly disappointed with this product and with Apple's continued failure to acknowledge a design flaw in this iMac.

I'm really angry when I think that my Mac Book Pro works perfectly after 10 years and I have no intention of spending 900 euros to repair the iMac to replace the display with only a 90 days warranty!

Dec 9, 2025 8:15 PM in response to latVm

This is trully manufacture defect on screen designed because almost every user experienced it with same problem.

I don't know it will affect on iMAC M3 or M4 on the future and it's make me worry because right now I have M3 IMAC that I bought it at 2024 June.

I bought M3 IMAC because my M1 IMAC experience (2021 November) the same issued with persistent lines on screen on (2024 May) take a looked on my last post

Jotap62

Level 1

109 points

Dec 10, 2025 12:38 PM in response to RobertoDQ

Hi RobertoDQ.

Thanks for your explanation.

Are you aware that the same issue will very likely occur again with the display you purchased?

The fault lies in the display itself, not in the computer.

You mentioned that you “bought a new display on A##zon and replaced it myself; it cost around $350. It’s not difficult, but you need to be careful because some connectors can break if pulled too hard… The display is now working 100% fine.”

Would you be able to explain in more detail how you carried out that replacement?

A clear, step-by-step description of the procedure would be extremely helpful. Many people might consider following your guidance, or alternatively decide to entrust their iMac to a technician after understanding what the process involves.

A detailed explanation of the steps you took would be greatly appreciated.

It's a solution that isn't without some risk, but it is a solution, and someone else may be tempted to follow in your footsteps.

Dec 11, 2025 6:13 PM in response to latVm

I am yet another user experiencing this issue. I spoke with an Apple Care Specialist and was encouraged to get the repair done by an authorized repair technician or company so that if the problem ever becomes a "Supported Repair Case" I can be reimbursed.

I am posting this here so that Apple has a chance to see that yet another user has been affected by their hardware issue.