UI_a112 - USB device malfunction - I/O Error

[BitJam]

Yup, fresh out of the factory on Tesla's latest and greatest and the UI_a112 notifications started spewing out. I have scheduled a SC appointment just so I can get this issue logged in their books but based on what everyone has said there's no point in 1) swapping flash drive 2) changing the USB hub 3) changing the MCU. Will just have to wait for the SW fix.

Replacing the computer worked for at least one person:

My USB-A wasn't recognized, and the format and delete options were grayed out. I tested the USB on my computer, it worked perfectly fine. Tesla verified that there was an issue and replaced the computer (1684435-S0-1). Works fine now and sentry is working.

I've mentioned before that Tesla almost certainly uses different usb controller chips in different vehicles and even in the same vehicle. Each controller chip can use a different software driver. If one of the drivers is bad the problem can affect some cars and not others. I'm one of the people who has a consistently working glovebox usb port but a non-working center console usb port.

It seems at least possible that the service center will be able to fix the problem for you by swapping hardware.

 

[Mike_TV]

I've mentioned before that Tesla almost certainly uses different usb controller chips in different vehicles and even in the same vehicle.

During the supply chain issues in 2021-22 they said one of the things that Tesla delivering cars was being able to write firmware, on the fly, from different chipsets and vendors that had then in stock. Something like 26 different chip designs for the same purpose.

 

[Tha_Ape]

I have only seen the error on my 2021, and only with the center USB-Cs.

No issues with the glovebox one in either of my cars

 

[ElectricAnt54]

I believe have seen people with older model 3 which lack glovebox usb port (so they claim) have the issue in their center console usb-a ports. Basically they have no way to have functional dashcam feature & sentry mode…nor usb music.

Personally my 2022 model y with Tesla OEM usb-c module which supports data has the issue since 2/2024 & my glovebox usb-a works fine.

 

[BitJam]

During the supply chain issues in 2021-22 they said one of the things that Tesla delivering cars was being able to write firmware, on the fly, from different chipsets and vendors that had then in stock. Something like 26 different chip designs for the same purpose.

Good point but I think this is something different. Tesla would write code for micro-controllers which I'm sure abound in the car. But they probably wouldn't write low level code to interact with a usb controller. That is usually done with a driver in the Linux kernel. The kernel uses the pci id of the controller to know which driver to load so, as long as nothing goes wrong, changing usb controllers is transparent to the Tesla devs.

I'm sure Tesla periodically updates their Linux kernel as part of some firmware updates. If a bad driver got into one of the updates then it would explain much of what we are seeing. The problem would start after a Tesla firmware update. Some usb ports on some cars would have the problem. Other ports on other cars could be okay. A hardware swap might fix the problem for some people.

A bug in a driver that is part of the Linux kernel would also explain why this problem hasn't been fixed quickly. AFAIK, Tesla engineers are not working on the Linux kernel. For a minor problem** like this, Tesla would wait for the fix to get into the next stable kernel instead of patching their kernel to add only this fix. In addition, a Tesla firmware release with a new kernel will need to go through more testing than a normal point release would require.

You can find out more about how a computer interacts with usb controllers here: Extensible Host Controller Interface. The Linux driver for this is called xhci-hcd. Over the years there have been several similar problems with this driver where people lose connection with their usb devices and need to reboot to fix it.

** Lives are not at stake nor is FSD or Autopilot.

 

[Flybyglass]

I believe have seen people with older model 3 which lack glovebox usb port (so they claim) have the issue in their center console usb-a ports. Basically they have no way to have functional dashcam feature & sentry mode…nor usb music.

Personally my 2022 model y with Tesla OEM usb-c module which supports data has the issue since 2/2024 & my glovebox usb-a works fine.

I have a 2020 Model 3 with the center console dual USB-A ports and no glove box port. The USB A's work and dash cam works but I get transitory UI_a112 like many others and have done the drive change to from 256GB to 128GB with same results. It happens at odd hours when car should be asleep like a data pull from Tesla but even some have selected no data sharing and they still see it. It doesn't generate any messages min service mode and no messages are active only past and don't appear to be interfering with anything. Since this is happening across all model years it must be software.

 

[ucby]

Good point but I think this is something different. Tesla would write code for micro-controllers which I'm sure abound in the car. But they probably wouldn't write low level code to interact with a usb controller. That is usually done with a driver in the Linux kernel. The kernel uses the pci id of the controller to know which driver to load so, as long as nothing goes wrong, changing usb controllers is transparent to the Tesla devs.

I'm sure Tesla periodically updates their Linux kernel as part of some firmware updates. If a bad driver got into one of the updates then it would explain much of what we are seeing. The problem would start after a Tesla firmware update. Some usb ports on some cars would have the problem. Other ports on other cars could be okay. A hardware swap might fix the problem for some people.

A bug in a driver that is part of the Linux kernel would also explain why this problem hasn't been fixed quickly. AFAIK, Tesla engineers are not working on the Linux kernel. For a minor problem** like this, Tesla would wait for the fix to get into the next stable kernel instead of patching their kernel to add only this fix. In addition, a Tesla firmware release with a new kernel will need to go through more testing than a normal point release would require.

You can find out more about how a computer interacts with usb controllers here: Extensible Host Controller Interface. The Linux driver for this is called xhci-hcd. Over the years there have been several similar problems with this driver where people lose connection with their usb devices and need to reboot to fix it.

** Lives are not at stake nor is FSD or Autopilot.

This explanation seems plausible. I agree that there will be multiple sources for USB controllers as all large companies will use multiple vendors to limit supply risk and improve pricing. This might explain why an MCU swap could fix a firmware issue as the change may swap in a USB controller from a different vendor that doesn't have the compatibility issue.

BTW, when I look closely at the UI_a112 errors report on the web I think people might have different issues that are all grouped under the same error. Some people report that once they see the error the USB drive is no longer mounted and requires a reboot / reformat / unplug and plug / etc. I don't see that. Me USB drive stays mounted and Dashcam is recording ok. The only issue I see is the error in my notification at random times. I'm guessing the drive may be unmounted but gets remounted automatically.

 

[legendsk]

But more importantly, does the Screaming Goat noise still work with 2024.14.9? Mine shows a pending update waiting and I'm afraid to install it. I would hate having to go back to hauling a passenger in order to have the screaming goat noise, when the car does scary stuff.

 

[⚡️Mr. JARE_EE]

I am experiencing same issue 2020 MY with center console usb. It is happening every morning in deep sleep. I am trying to see if it is because of the schedule departure in the morning. My USB is the Samsung Bar Plus. At first i thought it was my SD card so i changed to USB. Currently on 2024.14.9.