My aging 2015 car has one big problem: it doesn’t have Android Auto or Apple CarPlay. I didn’t really mind, as I could always connect my smartphone to the in-car audio using a cheap USB-C to 3.5mm adapter to keep the music playing, no matter what.
That is, until I noticed that more and more of my smartphones were failing to work with my good old adapter. Everything worked fine when I used a Nothing Phone 1, but with the Samsung Z Fold 8? It doesn’t want to know.
A $20 adapter solved my problems overnight, and my wonderful Car Music playlist booms out wherever I drive once more — but why did the USB-C to 3.5mm jack adapter stop working to begin with?
Why your USB-C to 3.5mm jack adapter doesn’t work
Well, not with the latest smartphones
The dreaded “USB device message not supported” isn’t entirely new; Samsung users began reporting this issue back in 2020 with the Galaxy S20, and that wasn’t the only phone flashing this message. But I’d been somehow getting away with the problem for years, not just on my beloved Nothing Phone 1, but a whole host of smartphones across that period.
The problem is mixed: it’s a phone problem, for sure, but it’s also an adapter problem.
In part, it starts because all USB-C to 3.5mm adapters and conversion cables look essentially the same from the outside: a plug at each end, wire between, and a tiny DAC somewhere in the process converting the digital signal into analog.
But in some cases, the cheap ones are passive, requiring the phone’s USB-C port to recognize the adapter’s resistor configuration and support USB-C’s Audio Adapter Accessory Mode. When it does, the phone routes analog audio through the USB-C connector.
So, when the handshake does work, it’s essentially the same 3.5mm signal your old car stereo has always expected. But the handshake is never truly guaranteed with passive adapters, relying more on the implementation of the device to support the audio mode.
The manufacturers aren’t entirely to blame
USB-IF reassigned the pins
What’s really fun is that it’s not the phone manufacturers phasing out tech they don’t want to support anymore.
In 2024, the USB Implementers Forum published Revision 2.3 of the USB-C Cable and Connector Specification, the update that formally deprecated the Audio Adapter Accessory Mode and replaced it with something called Liquid Corrosion Mitigation Mode on the same pins. So, instead of processing audio, those same pins now make sure you don’t cook your device when it’s slightly damp.
As much as I find this frustrating, I can’t deny that not having your entire phone wrecked by some water damage isn’t useful.
The specification change essentially reflects a direction the industry had already been heading in. Samsung users were encountering compatibility problems with passive adapters years earlier, while current Samsung guidance recommends using a USB-C-to-3.5mm adapter with a built-in DAC, as do many other manufacturers.
Given where smartphones, USB-C, and general audio processing are, it’s not an unreasonable move. Unless you’re like me and stuck using a device — my car — that you don’t want to change for the sake of listening to music a little easier.
I fixed my in-car audio for under $20
But you can probably do it cheaper
I fixed my in-car audio problems with a UGREEN Bluetooth 6.0 to 3.5mm dongle that cost me around $20. I plugged it straight into the car AUX port, fired it up, connected my phone, and away I went.
It’s remarkably simple, but also really handy. The UGREEN dongle can operate with two connected devices, which is a nice touch, meaning two smartphones can connect and play music. But it also features a transmitter and receiver mode via an adjustable physical toggle. Battery life is also pretty good, running for up to 18 hours, and the ability to connect to most Bluetooth devices in one way or another.
I went with the UGREEN model because I wanted the extra features and I trust the manufacturer. But you can find more basic Bluetooth-to-3.5 mm adapters, such as the Essager Bluetooth Receiver, for under $10, and at times, even less.
I haven’t tested these cheaper models, but many have good, four-star-plus ratings, which suggests they’ll get the job done.
I still don’t have CarPlay or Android Auto, but that’s okay
I’m still a little salty I don’t have Android Auto. My setup is now better than it was, no doubt, as I can put my smartphone in a holder, use split-screen on my phone to run Google Maps and Spotify, and pretend I’ve got the real thing.
Alternatively, apps like the headunit emulator Headunit Revived turn any smartphone into an Android Auto device, and are a handy workaround in combination with a Bluetooth to 3.5mm dongle.