After upgrading to macOS Big Sur my MacBook Pro 2017 constantly heats up even when it not in use which was not the case before upgrading. I have A MacBook Air which do not have this problem.

When compared kernelmanagerd process is constantly using 50% of the CPU in my MacBook Pro in MacBook Air its almost 0%. I have uninstalled all third-party kernel extensions still the problem exists.

Is there any way to find which extension is using the CPU?

1 Answer 1


I found the cause of the problem, it is Karabiner-Elements.

Funny thing was I have installed Karabiner-Elements in my mac when it ran macOS High Sierra but I immediately uninstalled (I was trying something with it) but some residue was left behind.

Today when exploring the activity monitor, I noticed some karabiner process was there, so i installed the latest version of Karabiner. Instantly i noticed kernelmanagerd CPU usage became 0.0.

Then I uninstalled Karabiner as in this document

Now my MacBook Pro is normal.

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