SONOMA 14.4 Kernel_Task CPU usage extremely high

Issue finally resolved, but here is the brief recaps.

Before I installed SONOMA 14.4 my iMac 2019 was running perfectly fine.

I only have Adobe Photoshop and Lightroom Class running, and occasionally watch Netflix or run some FB games.

Because I do run process a lot of stuff through Adobe from time to time, so I would have my Task Monitor open at all time to monitor my CPU or Memory pressure.

Immediately SONOMA 14.4 was installed, I noticed when I run FB game “Kernel_Task” would run over time, but I do not detect any fan noise.

I Googled up what “Kernal_Task” is, I found out it is a program that controls the cooling fan. So I noticed my iMac would get really hot by touching the back of my unit.

I tried to restart or even shut down to let it cool for a few times, it didn’t work, “Kernal_Task” will stay running extremely high, and my iMac hot.

Until I finally realized if I put it down to “Sleep Mode” it would reset the “Kernel_Task” issue, but it only resets it, not fix it.

I followed the instruction from Apple Online Help from an advisor, I have ran it through Safe Mode, and eventually format the whole thing with a fresh clean MacOS the issue still persist. So finally I contacted Apple Support again, they advise that I need to contact a Senior Advisor, and which lead to an appointment to bring my unit in for a physical check up.

At the check up, they determined the fan is faulty, and it needs to be replaced.

After a week and some money spent, I got my unit back, restarted it via TimeMachine, ran a few test to and so far it looks like it is working fine now. It still runs a bit hot, as I can still feel quite a lot of heat venting from the unit, but at least the Kernel_Task is not running at 70% of my CPU.

I think my situation was, the update somewhat killed my fan, so instead of notifying me what could the the issue, SONOMA is running over time try to initiate the fan.

I am happy I was able to fix it, but I still think that SONOMA 14.4 some what trigged the problem.

The point I wanted to make is, I have very simple and clean Mac setup. I kept plenty of space available on my HDD, I don’t have any VPN, Mac Cleaner program installed, that could cause the problem. I have unplugged all external Hub, printer accessories during my trouble shooting, so it was not caused by fault external devices.

Possible cause of the issue combining my personal experience and what I found online with who has similar issue, and spoke to people with the same issue:

1. Updating to SONOMA 14.4.1 “could” fix the issue. My friend had the same issue on his MacBook with M1 chip, after updating to 14.4.1 it is fixed.
2. SONOMA 14.4 is a massive update, so it requires a lot of CPU processing, which probably triggered the overwhelming work on my fan, and eventually killed it. This is my case. So the only solution is to replace the fan.
3. SONOMA 14.4 has many compatibility issues with either hardware of software, which cause some kind of conflict in programming, and SONOMA is stuck at a loop trying to correct it.
4. SONOMA 14.4 is not an efficient MacOS, it requires a lot of more CPU usage, or cause more hardware heating, so if you have an older unit, either the fan needs cleaning or the fan is not working efficiently, the program is unable to resolve the issue by software correction, instead it is telling the fan to run faster, harder, but in this vicious cycle, it just cause your computer to run even hotter until something fails. So probably the best solution is to get your unit cleaned up or get a hardware check, because your fan is probably dying or dead.

I still think the culprit is SONOMA 14.4, and maybe as a conspiracy Apple is trying to force you to upgrade to a newer unit, or maybe Apple has just got more MS and releasing more half baked software and have the consumer to test their program for them. I can’t really say, but for the future, I will definitely delay my updates unless it is totally necessary.

In the past, I had faith with Apple, updating whenever I could, and never had an issue, and my iMac could usually last for 5-7 years with no problem.

Surely, with more program update, and especially with AI advancement, my computer is running much slower as it would be in the past, but it would still be useable. I mean, I was still using my 10 year old MacBook Air during my iMac downtime.

Apple do make good products, and I love their eco system, that’s why I have not switched, but I would be cautions with their updates now, since I don’t know wha it’s their business strategy now a days.

And most importantly, do make Backup frequently, TimeMachine is still one of the best backup system I have every seen. My system was 99% functional, with only the exception of Loupedeck require re-installation.

I already was prepared for the worse case scenario I would need to get a new unit, but with my TimeMachine backup, at least I would still have all my work in tack.

Latest update.

Apple came back with the inspection and confirmed my cooling fan is bad, and a replacement fan should fix the problem.

I will see when I get it back this week.

But still, I think the SONOMA 14.4 triggered the kill on my fan, because overheating and fan on all the time with MacOS SONOMA is all over the internet.

As far as I could suggest is that, if you hear you kernel_task is high, but you do not hear the fan running high, you better go to Apple to check your fan, because your fan might be dead, so instead of end up with a burnt CPU, I think it's cheaper to get it repaired.

Other than that, format, reinstall, update to SONOMA 14.4.1 or even down grade, seem to fix some of the user's issue, but I do see someone with 14.4.1 start to have overheating after update.

I don't know what is the real cause, although I think it is SONOMA, but these are just the fix I see on the web that might help.

My Mac was formated and reinstalled with no other program installed.

Problem still persist.

"What you describe could be Lack Of Empty Space on the drive."

Actually I have at least 25% of free space, and I freed up some more thinking it was lack of free space, too.

So I have over 30% of free space on my 1TB drive.

And I had not used more drive space since the issue started, while only thing I could think of is it probably start to happen after I updated to SONOMA 14.4.

I have contacted the Support Advisor, they sugguested running through Safe Mode to see if it persist, if not I'll have to reinstall my MacOS, which I really don't like to do that.

I have searched the web and found that quite a few people on different device has similar problem (search for SONOMA CPU heating issue).

I have seen other solves including stop Refreshing Wallpaper, and restart SMC twice, which I will try to see if that works.

I have formatted, down grade my MacOS, still not fixed.

a friend told me that 14.4.1 which came out days later would fixe the problem, upgraded to that, still no fix.

Eventually I sent it in for repair inspection, they told me my fan is dead.

I will not know if replacing the fan will fix the problem. I’m crossing my fingers now.

The cost and the wait for repair is not really a big deal for me, but I am still suspicious that 14.4 killed my fan.

After all, I have found tons of posts on Reddit, Apple Help Community, the over heating issue is happening across many platforms, iMac, MacBook, MacBook Air, while most complains about over heating or fan is always on that killed their battery (if it is a laptop).

I also came across, I think it is a MacBook M2, that after updating to 14.4.1 starts to have this issue.

I think it is a MacOS bug that triggered the kernel_task program error into an infinite loop, then lead to overheating issue in SONOMA, and in some platforms the problem would persist.

My computer has always been kept quite simple, while majority of the time I only runs Adobe Lightroom Classic and Photoshop, and my drive would kept with over 30% of storage space.

I would kept my Task Monitor running at all time to monitor my CPU and memory load, and before the 14.4 update everything was fine, so I am more concerned it should be an MacOS bug.

Apple really need to fix this.