16-inch MacBook Pro Bluetooth issue

I had exactly the same problem (down to every detail) and I think I just found a solution.

I'm also using a CalDigit dock and USB bluetooth stick and I'm on my second MBP 16. The first was replaced under AppleCare after the bluetooth module became apparently dead.

The built-in bluetooth came back to life by running system diagnostics (hold down D during boot). After the subsequent restart, without the USB bluetooth adapter attached, I noticed that bluetooth was seeing some devices in the area but still not connecting to anything. I deleted and re-paired my Magic Mouse 2 and Magic Keyboard 2 - now all is working again.

Hi,

I have been able to solve this exact problem by:

1. Shutdown the Mac completely
2. Plugin any supported usb bluetooth dongle while Mac is off
3. Start the Mac and login to the system
4. Use bluetooth to find and connect to some bluetooth device (propably optional step)
5. Remove the usb bluetooth dongle
6. Internal bluetooth started to work again normally

Also if this doesn't work first time you might want to repeat few times and try combinations where you shutdown the Mac with and without the dongle and startup the same way with and without the dongle.

--

Before this I also did following:

1. Reset NVRAM
2. Reset SMC
3. Reset the bluetooth module
4. Remove bluetooth.plist
5. Used bluetooth explorer.app
6. Booted to recovery (CMD+R) on startup

--

I think this is somekind of firmware related problem where call to re-enable internal bluetooth is not executed properly in certain situations leaving the bluetooth in unusable state.

Solution in my case was insipired by similar headphone jack problems on older models where Mac thought that jack was plugged in and disabled onboard speakers even if no jack was connected.

Hi,

I changed the procedure a bit as NVRAM reset was pain to do as I have firmware password set.

Doing SMC reset instead.

https://www.youtube.com/watch?v=2elFJmqJJtI

---

1. For demo purposes I have already broken my internal BT with CSR 4.0 BT dongle

2. Disconnect CSR 4.0 BT dongle if it is still connected

3. option+shift+bt icon - debug - reset the bluetooth module

4. Run “sudo rm /Library/Preferences/com.apple.Bluetooth.plist”

5. Shutdown your Mac and do SMC reset

1. My procedure is following as I have filevault enabled

1. Start your Mac

2. Wait until filevault login appears

3. Press option+cmd+RIGHT SHIFT for 7 seconds

4. While keep holding keys in step 3. also press power button for 7 seconds

1. Fans should briefly spin up and Mac shut power off, keep holding power button for whole 7 seconds

5. If fans did not spin up try SMC reset again

6. Start your Mac to macOS normally without connecting any dongles

7. See Ya soon…

8. After SMC reset

9. Insert BT 2.0 USB dongle

10. Initiate pairing but cancel it from macOS

11. Remove BT 2.0 USB dongle and immediately after try pairing again

12. Failed

13. Trying again

14. Connect your BT 2.0 USB dongle

15. Initiate pairing but cancel it from macOS

16. Cancel pairing then remove BT 2.0 and try pairing again

17. Failed

18. Do step 5. again

19. Check if internal bluetooth is working already

20. Internal BT works again if it does not try steps 9-11 again

21. Done

Here is a summary of the whole thread:

TL;DR:

• It's apparently possible to unfix the problem with a BT 2.0 dongle
• For those that are scared to break it again (after logic board replacement OR BT 2.0 fix), they can run a NVRAM command to never switch BT controllers again (need to re-run after NVRAM reset):

sudo nvram bluetoothHostControllerSwitchBehavior="never"

Might be best to put that in a startup script and only change if needed.

• It seems to have to do with Power Management and seemingly a EFI firmware bug introduced in Catalina as it's not possible to break Mojave in the same way.

So in summary it's several factors that came together here to create this bug:

• a) A likely firmware bug in the EFI in Catalina.
• b) A pretty unsafe default for switching Bluetooth controllers - which most users likely don't want anyway.
• c) Maybe: A CSR USB controller using the exact same chip as the internal one. (if I am able to unbreak my device, I will try to re-break with a Broadcom 4.0 device, too)

Long version:

I have been bitten by the Bluetooth bug, too that breaks the internal Bluetooth module on Mac Book Pro 16inch if you accidentally plug in an USB CSR 4.0 Bluetooth dongle.

• It seems to not happen on Mojave - so it's also related to a driver bug in Catalina regarding power management.
• It happens in the first place because the nvram default behavior is to switch over to external Bluetooth by default.

The symptom is:

• The Bluetooth chip gets too little power and hence fails to connect to devices and if it does connection is spotty. While on MacBook Pro 16inch it completely fails, other Macs can have bad Bluetooth behavior that is "spotty".

• The solution of AppleRepair so far has been to completely replace the logic board, which fixes it till the next Dongle is plugged in and obviously is quite costly for a pure software bug.

Several observations:

• The current theory is that the internal firmware mixes up the external CSR chip for it's own and saves the power requirement of the external chip (which is less as its powered by BT) and then uses this for the internal chip.

• a) It is highly debatable to make the switch over to external dongle the default for all users if the functionality is usually only wanted by a handful of developers that develop Bluetooth LE applications. In fact it also breaks it for iOS developers and everyone that wants to use a Dongle to use with a VM:

• https://developer.apple.com/library/archive/technotes/tn2295/_index.html#//apple_ref/doc/uid/DTS40012211-CH1-UNDERSTAND_SWITCH__BEHAVIOR

• Fortunately that is easily remedied with a nvram command to change the behavior. It would be great if Apple changed this in the next minor Catalina release by default to not switch over to external Bluetooth automatically, but make it an option to select the Controller (like you can do with Bluetooth Explorer). The setting could be stored and automatically be applied after every reboot to what the user configured. That would prevent the bug in probably most user cases until a proper fix can be found.

• b) It is unclear if a pure software fix could fix this as per the reports the issue remains once it has happened even if you boot into Windows / Bootcamp. However it is seemingly possible (per the above accepted answer) to unfix that issue with an older CSR Bluetooth 2.0 dongle. This probably helps, because it has a different power requirement as it predates Bluetooth LE and hence the MacBook FW gives the internal Bluetooth chip more power again.

• c) Someone tried to port the Bluetooth drivers from Catalina to Mojave and it did not work.This points to the fact that it likely is an EFI / soft FW update that broke this in Catalina and not a pure software bug.

Overall it seems Apple would have several ways to fix / work around this:

• Fix the EFI to fix the PM bug. (that gives hope that it can be fixed 100% and also restored affected devices without logic board replacement)
• If that fix takes a while to do, at least change the default and put out a changelog for those few that need to use an external Bluetooth dongle to replace the internal one.
• Create a program that does whatever the diagnostics on the Apple Wifi in the repair shop does to reset the firmware to sane values.
• Create a device to emulate the USB behavior of a 2.0 Bluetooth device to fix broken devices [unlikely as that is].

In theory VirtualHere + ZeroTier could be used to share a BT 2.0 dongle from one machine on the internet to another one and unbreak something remotely. (not sure if that would work in practice though as emulation is not perfect. Though I know that Bluetooth over Internet works well as that is ironically how I broke my BT in the first place as I needed a dongle for bluetooth-over-internet)

I fixed my broken Bluetooth by replacing the Airport Wifi/Bluetooth Card of my MacBook Pro

I just wanted to add another possible Solution for some. Don't know if I had the same Problem as other visitors, but i got my issue solved.

My Issue was, that my Bluetooth did not see other Devices anymore. I do not remember ever using an external Bluetooth Dongle that might have caused this - as others here mentioned.

I tried some of the recovery methods in this Thread (with external Dongles): They did not work.

Then i just went on ebay and bought a replacement for the Airport Card, which does handle Wifi/Bluetooth on the MBP - for like 24€ it was worth a try. Replacement is trivial if you have the Apple Screwdriver Bit and some guidance (ifixit.com, youtube). Now everything works flawlessly again.

As I said before, this may not solve everyones Problem here, but maybe someone with the same Problem will read this ;)

Keep in mind to research which particular Airport-Card-Model you need for your Mac Model, before you buy it. There are different versions out there and some of them look very similiar to each other.

OK,

target mac's bluetooth was rendered unusable by some bt 4.0 dongle and I used other older bt 2.0 dongle to troubleshoot and eventually to get it working again.

To replicate successful recovery just yesterday that I did:

1. Cleared SMC, NVRAM
2. reset bluetooth from shift+option icon debug method
3. installed blueutil, with brew installed from terminal brew install blueutil
4. plugged in the bluetooth dongle and fiddled around it until bluetooth works with with the dongle (bluetooth explorer app, turning bluetooth on and off again multiple times)
5. connected to android phone using the bluetooth dongle (paired etc, also I had visible connectivity light on the dongle that I noticed to be blicking time to time)
6. removed the bluetooth dongle -> paired android device disappears from the bt device list
7. restarted to recovery
8. mounted macos partition in recovery
9. openned terminal in recovery
10. executed cd /PATH/TO/MOUNTED/MACOS/VOLUME + /usr/local/Cellar/blueutil/2.6.0/bin/blueutil
11. executed blueutil -p 0
12. executed blueutil -p 1
13. executed blueutil --inquiry
14. blueutil did not return anything even if android device was discoverable
15. rebooted to macos -> bluetooth still not working
16. shutdown the mac
17. plugged in the bluetooth dongle and turned on the mac and started macos
18. at this point discovering new bluetooth devices used the onboard bluetooth as dongle was not blinking
19. initiated pairing to android but cancelled it from the macos
20. removed bluetooth dongle
21. initiated pairing to android and completed it
22. restarted macos and internal bluetooth was still working

half of things in the list are probably not related why it started working again but this is how I did it.

I am still amazed how such things are even a thing on this expensive machine.

Latest updated, and its good news !

Booked in to a Apple Authorised Repair centre, fully expecting my MBP 16 to need to spend a few days with them and parts to come from Australia to NZ.

The service guy was super helpful and ran two diagnostics on it - one called EFI and the other Mac Resource Inspector.

These are only accessible via the special WiFi network in store and not the same as we can access by holding D while booting.

They both upload results to Apples support tools for the repair centre to see online and he showed me the results.

It said the Bluetooth Module passed and the MAC address was sane.

Then after a clean boot and a delete of the /Library/Preferences/com.apple.Bluetooth.plist file my MBP 16 would pair with the techs keyboard.

Then we tested with my mouse and keyboard in store and they worked, so far its been working for 4 hours perfectly !

Hope this helps someone else save time.

Meanwhile the USB Bluetooth dongle is being locked away and never used again on the MBP 16

Hi,

So I borrowed my friends CSR 4.0 BT USB dongle...

My Mac is following version:

Internal bluetooth is as follows:

...and spent 5 hours with it...

I was able to break my internal BT 5 times and recover 5 times :) but it was well very frustrating...

Following did the trick:

and sorry the list is still long :(

1. option+shift+bt icon -> debug -> reset the bluetooth module
2. sudo su
3. rm /Library/Preferences/com.apple.Bluetooth.plist
4. reboot (to filevault login screen)
5. NVRAM reset (I am not sure but I think the fans must spin up for half a second to the NVRAM reset to be successful, I missed timing many times and it seemed like a normal hard shutdown what happens when you hold down power button for long enough)
6. boot up to macOS normally WITHOUT BT CSR 4.0 connected
7. Trying to recover with CSR 4.0 didn't work even once (I tried 4 of 5 hours to get it to work as this is what most people will have available)
8. I connected my BT 2.0 USB dongle
9. scanned for my android device
10. Initiated pairing for android but cancelled it from macOS
11. removed the BT 2.0 USB dongle
12. immediately after connected to my android device and finished pairing with it
13. BT restored

One time I had to try steps 8 - 12 again

Once I had to do whole 1 - 12 again.

3 times I got it work exactly as listed

There was so much luck involved finding this...

Happy to finally delete this page from my bookmarks.

Here's what worked for me. You will need a device that can pair via Bluetooth for data transfer (audio only didn't work for me) such as a Windows PC or Android Phone.

1. Turn on Bluetooth
2. Reset SMC
3. Reset BT Module and remove devices in BT debug menu (option+shift+click)
4. Power off
5. Plug in 2.0 BT dongle
6. Power on. At this point your dongle should be picked up by the OS.
7. Grab your second device and attempt to connect to MacBook using Bluetooth
8. macOS prompts connection code, cancel connection
9. Remove dongle
10. Done

At first I had this issue:

You will see very soon if your dongle is working or not because it has to be directly recognized by mac. If you see that when you connect your dongle your Bluetooth icon changes temporary to an error icon it won't work. Your dongle has to be able to search for devices.

I managed to make it work by making multiple attempts of connecting/disconnecting and rebooting with/without the dongle connected. You will know it's working because other devices can pick up your Mac.

Best of luck, and don't give up. If you got your hands on a 2.0 BT dongle already, give it one more try.

Eternally grateful to @AntiHawk who figured this out, Apple should send you a check ;)

Thank you, @kelvin_hk_uk & @ndrock!

I had tried a bit using that old BT mushroom-head (https://www.amazon.com/gp/product/B00345SLGS) earlier, but as it never even showed any successful BT device-detections/attempted-connections, thought it couldn't work.

Now, after a number of repeated resets & plug/unplug cycles, it's had the desired effect: and my onboard BT is again alive.

At first, I simply tried repeated plugs/unplugs (without any other prep steps), just to see if I could trigger the "weird symbol stays" (rather than appears briefly after plug-in) state described by @ndrock. A few plug/unplug cycles that way actually triggered a kernel-panic hard-crash. (Apple ¡quality!) But, still no activity from the onboard Bluetooth.

But then I tried following @ndrock's directions more thoroughly - Bluetooth debug menu (activated all reset/forget options); delete Bluetooth plist; shutdown-reset-SMC-reboot; reset-NVRAM-reboot; repeated plug-and-unplug of the B00345SLGS adapter.

I did *not* achieve a persistent 'weird symbol' (wavy-lines) state, even with many different-timed plug-unplug cycles. (I thought maybe the state was only reachable via some lucky timing - while it would sometimes stay 'wavy' for ~5seconds, it'd always progress to normal or grayed Bluetooth icon,) But I eventually just opened the system bluetooth prefs (to see how it was reacting to plugs/unplugs), then chose system shutdown while also plugging/unplugging. My machine shutdown *with* the B00345SLGS dongle plugged in; I unplugged it while the machine was 'off', and then on the next reboot, normal onboard Bluetooth worked.

Black magic but better than a warranty motherboard replacement.

What does system report say for bluetooth component (what is the Manufacturer set to)? Before I issued commands listed above, manufacturer ID was set to Cambridge Silicon Radio, even though external dongle was not plugged in. Now, it is set to this:

 Handoff Supported:	Yes
 Instant Hot Spot Supported:	Yes
 Manufacturer:	Broadcom
 Transport:	UART
 Chipset:	4364B3
 Firmware Version:	v50 c4178
 Bluetooth Power:	On

Also, it may be a long shot, but you could try running extra commands to explicitly remove the controller switch behaviour and internal controller info (though it seems that those should be deleted when 'sudo nvram -c' command is invoked):

sudo nvram -d bluetoothHostControllerSwitchBehavior
sudo nvram -d bluetoothInternalControllerInfo
sudo nvram -c
sudo reboot

Hi all,

Just got my 2019 MBP back from an authorized repair shop. Almost 1 month wait for the **** laptop! They ended up changing the logical board AND the touch ID (which seem to be the reason why it took so long - there is a shortage of Touch ID devices for my model it seem).

All in all, I'm pretty confident this is something that could be avoided by Apple. This is the kind of behaviour that puts a dent on the brand as it shows that wanting to move in that direction (every component soldered on the board) might be cost effective but brings a lot of issues when having hardware problems - we're talking about a bluetooth adapter here....

As for the other folks, don't want to sound negative here but I've tried all steps posted here, multiple times without any success. I had to buy 3 different adapters without the results we all know and it seem to be a hit or miss more than anything else. In the end, I had to send the laptop back to Apple for them to change the whole internals.

Best of luck!

Got mine back in 3 days at a official repair point, should never take 4 weeks!

Trust me, just got mine back from the repair point and the replaced the whole board just like others explained here. The internal BT just doesn't work and they have to replace the whole board, just do it under warranty and your all good to go after a few days/weeks.

Make sure to never plugin a BT dongle again :)

Only way to fix the issue is have the motherboard replaced, I just got my MacBook Pro back, took 3 days from shipping and getting it back. Made a time capsule backup before, and now everything works, not plugin external bluetooth dongles on my MacBook Pro.

holy sh*t, just want to confirm that after 2 months with no builtin bluetooth I managed to fix mine by doing @AntiHawk procedure using an old cheap bt 2.0 device.

I basically connected BT 2.0 device into my pc (and unplugged it, didn't connect to anything just let it search), opened terminal and deleted bluetooth plist, then reboot mac and cleaned nvram.

After this it started working again, I didn't even need to plug the usb bt again...

thanks @AntiHawk!

=== EDIT

I think that this basically shows that this is some really hard to debug software bug rather than short circuit into bt internal module like some said, it does make sense since bt and wifi use the same internal chip, so breaking one without breaking the other would be kinda crazy...

I think we just helped apple save couple hundred thousand U$D in replacement costs