My CPU load spikes to 900% in Activity monitor because of faulty fan sensor

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Level 1

4 points

My CPU load spikes to 900% in Activity monitor because of faulty fan sensor

I have a 2013 Trash can Mac Pro and about 6 months back the fan started coming on in full throttle even though the CPU load was minimal.I ran hardware test (D key) and I got PFM006.I have been using Mac Fan control (free version)for about 6 months now without any issues but now even when I lower the fan speed ..the CPU load in Activity Monitor is hovering around 900 % and the computer has become really slow.

I Reset NVRAM/PRAM/disk repair/boot in safe mode/single user mode ...tried everything but no use.

My second last option is to use apple ASD and last would be to reinstall OS Catalina from recovery mode

If anyone has any advise ..I would be highly grateful

[Image Edited by Moderator to Remove Personal Informtion]

Mac Pro

Posted on Sep 8, 2020 11:38 PM

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Answer 1

Eric--F

Community Specialist

Sep 9, 2020 7:49 PM in response to djsanjeev

Hello djsanjeev,

Thanks for asking the Apple Support Communities for help with SMC code PFM006.

You might want to try the SMC reset first: How to reset the SMC of your Mac - Apple Support

If you still have issues, the alert shows you need the computer diagnosed by an Apple Authorized Service Provider or Apple Store: Apple Diagnostics: Reference codes - Apple Support

You may want to contact the Apple Authorized Service Provider in your area and ask if they require an appointment to check the computer. Please make an appointment if you are visiting an Apple Store.

Please make a backup before taking the computer in to your appointment: Back up your Mac with Time Machine - Apple Support

Also, you will need to have your Apple ID and password handy when visiting a service provider. Check this help article under the bottom section titled "Get ready for service" for other items to ensure you are prepared: Mac Service and Repair - Apple Support

"Get ready for service

Before you return your Mac to us, be sure to enable FileVault and back up your data. You may need the backup if your Mac needs to be reformatted during the repair process. Apple isn't responsible for lost data.

Read the Apple privacy policy"

You can find a service provider using this link: Apple Find Locations

Thanks and have a wonderful day.

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Answer 2

djsanjeev Author

Level 1

4 points

Sep 10, 2020 8:06 AM in response to Eric--F

I third the SMC reset but to no avail.Then I ran EFI boot test from Apple Service Diagnostic ASD 3S159 and I got these errors.

(PFA Screen Shots)

All this while Mac Fan Control was managing and in fact yesterday I managed to boot fine into Catalina and do a full Backup to Time Machine.Everything was working smooth like old times .No CPU spikes/lag/no fan in full throttle

But today again the same problem ...CPU spike to 900 %. Now using TG pro software to manage fan speeds but to no use.

My question is

Can I individually replace the fan sensors or change the whole logic board?
Are the parts/Logic board still available if that's the last resort?

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Answer 3

Sep 10, 2020 8:30 AM in response to djsanjeev

The way your Mac was designed to work, the System Management Controller reads all the sensors multiple times a second. As long as all temperatures are within limits, the fans are turned down to reasonable speeds. Fans hardware fail-safe at maximum speed.

If sensors show unreasonable temperatures (or out-of-bounds values), the fans will be set to maximum speed AND Kernel_task idle loop will take over the machine to use up all available cycles to stop excessive heat-generation.

The remedy for all of this is to get your sensors fixed. There is no playbook for how to work around dead sensors.

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My CPU load spikes to 900% in Activity monitor because of faulty fan sensor

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