Persistent horizontal lines appear on iMac screen

Hey everyone, I wanted to share my experience in case it helps other M1 iMac owners facing the same display issue.

Before I contacted Apple, I came across another user’s post describing their own experience with a display failure and a successful goodwill repair. Reading that gave me the confidence to seek a goodwill review for my own case instead of simply accepting another expensive repair bill.

Now that my case has been resolved, I wanted to return the favour by sharing my own journey in the hope that it may help someone else in a similar situation.

My timeline:

• Purchased my M1 iMac in Jan 2022.
• In 2024, the display developed horizontal lines. I paid out of pocket (~SGD$800) to have the display repaired through Apple.
• In Apr 2026, the exact same issue happened again. Horizontal lines reappeared on the display, while the Mac itself continued to work normally. I connected it to an external monitor, and the external display worked perfectly, suggesting the issue was isolated to the iMac’s built-in display.

Since this was the second time the same component had failed, I contacted Apple Support and explained that this was a repeat failure after a previous Apple repair.

The process I went through was:

1. Contacted Apple Support and have them escalate my case to a Senior Advisor.
2. I was asked to visit the Genius Bar for diagnostics.
3. After the Genius Bar confirmed the display hardware issue, I was asked to proceed with the repair first. I was told that the goodwill review could only be processed after the repair had been completed.
4. The repair was completed (the repair cost was around SGD$900), and I informed the Senior Advisor as instructed.

Unfortunately, communication stalled after that. My repaired iMac remained at the store for weeks while I waited for an update from the Senior Advisor.

I eventually contacted Apple Support again, and a new Senior Advisor took over my case.

The new advisor submitted a goodwill repair request to management. It was rejected twice. I asked whether my case had clearly highlighted that this was a recurring issue after a previous Apple repair. The advisor explained that the previous case notes already documented this, but he submitted another review specifically emphasizing that this was a repeat failure.

That final review was approved, and Apple granted a full goodwill waiver for the repair.

From the time I first contacted Apple until the goodwill approval, the entire process took about slightly more than a month, so if you’re going through something similar, be prepared that it may take some time.

A few things I learned from this experience:

• Be polite and patient throughout the process. Every advisor I spoke with genuinely wanted to help.
• Clearly explain that this is a repeat failure of the same component after a previous Apple repair if that applies to your case.
• Follow all requested diagnostic steps and keep your case history consistent.
• If your case goes quiet for an extended period, don’t be afraid to contact Apple Support again. In my case, having another Senior Advisor review the case ultimately made the difference.
• If a goodwill request is initially declined, it may still be worth asking for another review if there are important details that deserve additional emphasis.

I’m not suggesting this outcome will apply to everyone, as every case is reviewed individually. However, if you’re experiencing a repeat failure after a previous Apple repair, it may be worth politely asking Apple to review your case for a goodwill repair.

I hope this helps someone else who finds themselves in the same situation, just as someone else’s post helped me.

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.

It´s a hardware issue.

But, because the (1 dollar) component it's causing it is not accessible, the only fix is an all-new (600-800 dollar) LCD.

My advice, at this moment, is to get a second monitor and turn the brightness of the iMac monitor to ZERO to protect it and delay its definitive failure as long as possible.

A 4K (27”-28”) monitor, with 350nits (or cd/m2) minimum, should work fine.

Color calibration will be the biggest problem if you buy a cheap monitor, but I was taught a trick which is to use the iPhone (or iMac monitor) to do it easily, by matching the monitor to the phone (or iMac) display. There are several videos to help with this technique.

I just received my repaired Imac. every thing looks beautiful and it is just like new! It only took 3 days total to fix and I paid zero :)

I am very thankful.

Overal process:

1. Kept apple in good consciousness and practiced released judgment and frustration and remained in forgiveness and non-attached frequency. 2 Reached to chat support and requested senior advisor 3. Had a genuine conversion about my appreciation for apple and how there is a case of manufacturing that can be happy to any company and requested for them to investigate this thread - as it is well documented. (Thanks to all of you) 4. She forwarded it to engineers and requested the photos and files from me, and within a few days had been approved for repair.

I trust this can be done for all the other people with the same issue and hopefully in the future if it happened again they can upgrade us to a newer model. May be we can all get an M3 ? :P

Talk soon!

My screen started flickering two days ago, June 18, 2024. I got my iMac 24' on March 14, 2022, with an M1 chip. I read the entire discussion. It is, for sure, Apple being sloppy, faulty and even rudely arrogant. Nothing else. They want to enforce Apple Care.

All screens went terrible after two years and a few months.

It begins with patchy flickers here and there, keeps widening and covers your entire screen, making your iMac unusable after a few days.

I would suggest getting a decent external screen. Ditch this old one. No use getting it repaired with no warranty and a one hundred per cent certainty that the replacement will also bite the dust after two years. And APPLE DOESN'T CARE at all! They want money. No accountability.

Hi everyone. Please be sure to report this issue directly to Apple via the Support Chat at https://getsupport.apple.com/solutions. They now have an Apple internal tracking number to capture reports specifically for this display issue on the 2021 iMac. If all goes well, this is a pre-cursor to an official out of warranty free repair program.

I learned about this while at the Genius bar with my 2021 iMac. The tech showed me the info on his support device that this issue is being tracked under an official Apple support issue number. It was like EF something. Anyway, DEFINITELY REPORT THIS ISSUE DIRECTLY TO APPLE SUPPORT!

Hi everyone. As promised, here's my story of getting a replacement iMac without paying money but effort and time. I'll only present below the timeline of my story and a few comments for brevity (since what I have done is as same as what have been told in this thread):

• June 2021: bought iMac M1 in Spain. I didn't purchase AppleCare because Spanish law provides 2 year warranty (later even extended to 3 year warranty). Since iMac always stands at one place, meaning little risk of accidental damage, double insurances for 2/3 years (AppleCare + warranty provided by law) seem excessive
• May 2024: flickering horizontal lines suddenly appeared in the screen (totally out of blue)
• Soon visited Apple Genius Bar to ask about solution without bringing in my iMac, and was told the screen needed to be replaced on my cost
• September 2024: visited again Apple Genius Bar and brought my iMac with me. The staff examined my iMac and suggested the same solution as before
• October 2024: contacted Apple via chat, and was given a phone call, where talked to a lady first, and then a senior advisor. As result, no change to the solution offered
• Afterwards wrote a formal feedback to Apple about my iMac
• End of October 2024: suddenly received a phone call from Apple, asking to have a session in order to collect some information about my iMac. System metrics were collected during the session. I was told Apple would analyze the information and decided what to do.
• 2 weeks later, Apple called me and told me that they would like to collect my iMac and provide me a replacement with no cost. The model of the new iMac would be as close as the old one. However, they can not be identical in my case: M1 is not available any more, M4 instead; the basic keyboard of the new model does not have touchID; the basic adapter does not have ethernet interface
• January 2025: I received the new iMac today. It's as expected

Thanks to everyone who contributed to this thread! You guided me step by step in this journey. Wish all of you get a replacement!

I planed buying a few Apple products but halted my plan due to the shock caused by the iMac deficiency. I'm happy I can buy Apple again after the replacement!

UPDATE

I faced an overheating issue in the top right corner of my 2021 M1 iMac 24”, which eventually led to display failure with burn marks and a smoke smell after 2.5 years of usage. Initially, Apple India denied free repair as the device was out of warranty and offered only paid service. I escalated the case to Apple USA with proof that this was a known horizontal lines issue (widely reported in forums and media) and highlighted the severe safety threat to my family. After sharing high-resolution photos, videos, and diagnosis reports, and insisting on escalation to their engineering team, Apple granted me a one-time exception (CS Code) for a free display replacement. 🙏 After 90 days of usage with the new display, it is working completely fine, and I sincerely thank Apple for their credibility and for standing by their customers in critical situations.

You're experiencing what many others are:

The following topics illustrate the Silicon M1 iMac Display problem:

Screen Failure on 24-inch-iMac, M1, 2021 - Apple Community

Persistent horizontal lines appear on iMac Screen - Apple Community

Horizontal Lines on Screen of iMac, 24", 2021

Horizontal black lines covering bottom 3rd of 2021 M1 iMac screen

Grey horizontal patches on my M1 iMac 2021 model

Horizontal lines at the bottom of iMac(M1,2021) screen

Horizontal Lines on 2001 M1 iMac Display

M1 iMac Display vertex heating to scorching 55°C  — Seeking Advice on Escalation

Horizontal Lines on iMAC with M1 chip

Currently there is no Service Program for that issue but keep checking this website in case Apple instigates one: Apple Service Programs - Apple Support.  

You have 3 options:

1 - have Apple repair the screen at a quoted price. 

2 - add a 3rd party monitor while darkening the iMac's screen.

3 - replace the iMac with a new M4 Mini: a 10 Core Mac Mini M4 with 16 GB RAM and 1 TB SSD ($999 + tax) with a 27" LG 4k monitor ($250 + tax from Amazon.com)  is $1249 + tax which is $560 less than a similarly configured new 24" iMac ($1799 + tax)  re 07/2025.  

I just got the above new Mini M4 with a 32" 4K LG monitor w/speakers (didn't realize the Mini came with a speaker). It was around $550 less than a. comparably configured new iMac.   You can always order more RAM, storage and cores in the CPU if needed.

I am having the same issue, and Apple was able to resolve it—quickly! (I REALLY appreciate all the advice below!)

Ten days ago, my 2021 iMac began having the same screen issues y'all are describing — flickering black lines at the bottom of the screen that won't go away. I tried to resolve it all the usual ways—restarting, updating the OS, hooking up the computer to an external monitor, etc.

Tonight, I went to my local Genius Bar in NJ (USA). I stressed my 26-year history as a loyal Mac user of many products, acknowledged that the iMac was out of warranty, and mentioned this thread, among many others. Would it be possible to get an exception, given the widespread problem with this model? The Genius Bar diagnosed it as a hardware issue. They couldn't grant an exception, and quoted repairs as $650. But they did suggest that I call customer support.

Tonight, I called 1-800-APL-CARE. I spoke KINDLY AND POLITELY to the rep and repeated all of the above story. They checked Apple Repair Programs and said there wasn't anything they could do. I then asked to speak to a Senior Advisor. Again, I repeated my story, and mentioned that I JUST bought a new iPhone, and that I was in the market for a new laptop—I wanted to get a MacBook, but I was nervous about Apple's recent quality given the issues with my desktop. He put me on hold, and came back to tell me that because they want their customers to be happy, he was granting me a ONE-TIME exception, for this product only, for just this once. Apple is repairing my iMac for free.

Needless to say, I'm thrilled with the outcome. Gotta give kudos to all of you on this thread for great suggestions on how to handle this situation!!!

Hello,

In some cases, you might still use the internal display of your iMac by doing the following:

1. Go to System settings. In Desktop & Dock turn off "Animate open Applications". Then go to Accessibility/Display and turn on "Reduce motion" and "Reduce transparency". Dim your screen from the keyboard to about 5 or 6 points. Then let your iMac sit for at least 3 hours.
2. When you turn back to your screen and find out that there are no more lines and the flickering has stopped, you may try the following.
3. Download the shareware TG Pro. They give you a trial period of two weeks. Open the program and observe the five temperature gauges dedicated to the LCD panel. On mine sensor 2 and 3 were the hottest. Note the exact temperature, when the flickering stops. Mine were respectively about 45 and 42°C.
4. Now in TG Pro settings establish two additional rules to limit the temperatures of these two sensors. Activate and use the "Auto boost" feature. Now as soon as the sensors are hot, the fans will turn on and try to cool down the screen. You may dim the screen light to help the fans do their job. Have fun!

Hi,

This problem is not rectifiable unless u change the Display hardware from apple, which is super expensive and still doesn't guarantee that it'll last perfectly after change... so no point !!

So next step is to get an EXTERNAL MONITOR.

Since most of us are so used to the iMac 5k screen monitor... it becomes difficult to adjust overnight to some other monitor... so here's the thing....

iMac M1 2021 model comes with the PPI (PIXEL PER INCHES)- 218 PPI

I stay in Bangalore, India and recently got a Dell QHD monitor for 23k with resolution QHD (2560 x 1440) with 109 PPI and it's so hard to get used to this screen... since suddenly ur PPI has dropped to half from Mac's 5k 218 PPI to Dell's 2k 109 PPI. You might see the Videos and pics quite clear... but when it comes to TEXT CLARITY... u will not find it easy for your eyes... as the clarity differs a lot (attached screenshot from my Dell QHD monitor below... as u can see the text is pixelated and not-so-clear).

Now imagine the text clarity when u try and buy a 1920x1080 resolution monitor... which will have below 100 PPI display quality.... hence the text readability will be still worse.

So my suggestion is to go for a 4K monitor which comes with a higher 163 PPI display for a better TEXT clarity on screen.

My current DELL QHD monitor costs me 23k and the next version 4k monitor costs 30k upwards. I'm now forced to return this QHD monitor and go for the EXPENSIVE 4K monitors... bcos Mac won't do justice to the display screen with lower PPI :(

Is Apple not aware of this issue or just trying to ignore? I am also located in Singapore, went to Apple Service Center last Sept 2023 and was quoted of SGD900++ to fix the issue. Very expensive and this is not caused randomly by any mishandling, this is really an issue on Apple's hardware and design of this iMac model.

I did not proceed to have it fixed, I just bought a second hand monitor and attached to this iMac for just $100.

But then again, Apple should not ignore this. How we can make this a trending topic in Social Media? Once this trends, I am sure Apple will do something as that will affect their future sales.

Any suggestion to make this trending? Maybe we can post a video in Youtube and TikTok?

@jot hey - here is how:

1. I used the normal support channels, to speak to the support through chat
2. In the chat conversions, I requested to be transferred to a senior representative regarding a special situation that I need the highest level to be able to help me.
3. I was then scheduled a call with a "senior representative who I Katherine"

Key points:

1. I kept doing forgiveness work, releasing apple and the situation and I became willing to let it go if they are not willing - so I wasn't coming from an angry voice tone, but from a calm, and genuine voice tone of wanting to fix this together
2. I made sure I am being calm and I expressed gratitude to apple and told her how I spent over 7K in the past year alone,
3. She already had seen this thread and she knew and agreed something is not right.

Realizing Apple is a multi-billion dollar company and they really do stand behind their product, now there is enough evidence here for them to help those of us in need.

Dear Alok Mishra,

According to someone, apparently, the problem lies in a cable that also powers the LCD.

This cable (of the FFC/FPC type or Flat Flexible Cable / Flexible Printed Circuit), has to sustain a very high voltage (around 50V) to power the LCD.

After a while (in this case after about 2 years) it starts to burn out and degrade at the connector side, to the point where it lets the signals leak between the various connectors and short-circuits some of them, which ends up causing those lines that we are all unfortunately familiar with.

The "ghost" we see is the signal bleeding from one line to the other due to the short circuits caused by the heating and cable degradation.

That was explained to me by someone who is a technician. But because I'm not a technician, the explanation may not be 100% precise. But I think it's quite accurate and clearly points to a hardware fault.