Fixing My MacBook Pro Random Shutdown Issue

TL;DR:

If you have a 2013, 2014, or 2015 MacBook Pro (either the 13 inch or 15 inch version), and are experiencing an issue with random shutdowns, the culprit may be a faulty “ethernet via thunderbolt” driver.

Step-by-step instructions to fix (originally found here):

1. Reboot with CMD+R pressed
2. Open Terminal and run
   csrutil disable
   (you may need to add
   sudo
   if that command fails)
3. Reboot in normal mode
4. (Only if running Catalina) Open Terminal and run
   sudo mount -uw /
5. In Terminal, run

sudo mv /System/Library/Extensions/AppleThunderboltNHI.kext
/System/Library/Extensions/AppleThunderboltNHI.kext.BAK

6. Reboot again with CMD+R pressed
7. Open Terminal and run
   csrutil enable
8. Reboot again and forget about the problem

Note: if you reinstall or update MacOS, you’ll need to redo these steps.

The Issue

This was a rough one. For years I had struggled with my MacBook randomly shutting off. For me, the precise symptoms were:

1. The computer would randomly freeze
2. Fans would kick on
3. Computer would stay on (but frozen) for about 5 seconds
4. Computer would shut down

At the time I couldn’t sort out what was going on, other than it seemed to happen the most when I was running on battery power.

Sometimes I would go a week or two between shutdowns, and other times it would happen 3 times within a 20 minute window.

System diagnostics didn’t reveal any problems, resetting SMC and NVRAM didn’t help, reinstalling MacOS didn’t help. I took it to the Apple Store, they couldn’t reproduce but said there was a 70% likelihood of it being fixed by replacing the battery (otherwise it was logic board or graphics card).

So I paid to get the battery replaced… and random shutdowns still happen.

The Fix

I had googled the issue many times before, and I’m not sure what magic string of characters I typed this time, but I finally ran across people describing very similar behavior. They claimed to have fixed it one of two ways:

1. Removing the ethernet via thunderbolt driver, or
2. Running a python script that would keep a small amount of CPU churn happening at all times

I started with the first option, and the issue immediately went away. This was further confirmed when I updated to MacOS Catalina. The update re-installed the problematic driver, and a day later I had a random freeze and shut down. I then re-removed the driver, and have been fine since.

I’m posting this article just in the off-chance it can help someone else suffering from this issue.

Resources

https://outluch.wixsite.com/rmbp-crash