Is this possible:

I have two USB-C ports on my MacBook Pro 2019. One port works perfectly well. The other is odd to say the least.

After some testing, it seems as if the port "can't handle strenuous tasks" and by strenuous tasks, I mean running a USB-C hub with external hard drives plugged in it or using the port to go to an external monitor.

It does work when charging my iPhone or using the port to charge the MacBook itself.

So my assumption overall is that it does work, but only small, less strenuous tasks, if that's even possbile?

Can any USB-C knowledgeable people confirm this is possible? Could it be a software issue?

I've tried resetting stuff like the SMC etc. just haven't reinstalled macOS yet, which is the last thing I'd wanna do, it's on the latest version of Catalina at the moment.

  • Do you know if any USB-C cable, connected on the problematic port, may have received a vertical shock (ex. : a glass fall, a cat walk…)? Do you feel any freedom of move vertically at the socket level? How much is it?
    – dan
    Commented Jul 28, 2020 at 6:27

1 Answer 1


You have a hardware issue.

And, unfortunately, it's a logic board problem.

  • The power rail not may not be delivering enough current to the USB bus
  • The USB controller for that side may be malfunctioning
  • The circuitry that connects the controller to the port may be problematic.

Unfortunately, without putting hands on with proper diagnostic gear it's impossible to know. In fact, if you take it to Apple, they will simply change out the logic board rather than identify and fix the problem.

The one thing you should do is an reset the SMC. There are different methods depending on your Mac model so be sure to read the steps carefully.

This is one of the actual few problems where an SMC reset is applicable - you're having power issues. Re-installing macOS is the last thing you should do - booting into Safe Mode or Recovery will get you a clean version of macOS without the hassle of overwriting your system and risking your data. You can also run Apple Diagnostics to see if there are any error codes.

Potential Workaround

If you can still transfer data, just not handle the "strenuous" tasks as you described, you may still be able to work with it if you use a powered USB hub. It will supply the power to the USB bus that your logic board can't

  • Yep, I imagined. It barely want to charge my iPhone let alone do anything else. I have no clue what caused this? How can something on the logic board just go? I have barely used the ports. Apparently some USB-C hubs can cause problems? Luckily I have it insured and I'll just get a brand new macbook tomorrow. I have tried the SMC reset, still nothing. I'll backup my Mac, perform a clean install on it and see if it fixes it, if not Ill get a replacement.
    – Nat
    Commented Jul 27, 2020 at 21:10
  • Things just happen - the quality of ICs are not what they used to be (like everything else). It's good that you have it insured. I'd probably take it in to Apple to see what the repair cost is (if the insurance company lets you keep it). If not, it has salvage value to the repair shops. They will strip the logic board for those components that haven't failed so they can fix other logic boards.
    – Allan
    Commented Jul 27, 2020 at 21:13
  • 1
    I would never not insure any products of that value. Thank god that I did! I'd imagine they'd take it back and give me a new one sadly. It's the model with only two USB-C ports so kinda need the second port.
    – Nat
    Commented Jul 27, 2020 at 21:15
  • For your work around, I already power my USB-C hub so that I can shut the lid on my macbook when it's connected to my two monitors. That still doesn't work :(
    – Nat
    Commented Jul 27, 2020 at 21:18
  • 1
    I'd be too scared. I cannot see how people can go about life like that. It's worth every penny in my eyes
    – Nat
    Commented Jul 27, 2020 at 21:19

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