Hi,

Don’t know whether this topic has been covered elsewhere, but is the USB C socket near the rear-view mirror on a 2020 mk4 Octavia capable of powering a dash-cam without any further wiring.

If so, can anyone recommend a current dash cam that would work ok with only this wiring configuration. Frankly, I’m not up to doing any wiring connection requiring fitting into into the car’s own 12volt electrics, nor do I want to start pulling trim about to hide any new wiring from a new dash-cam.

All suggestion very welcome

I have a Garmin DC Mini2 plugged into this socket via a short USB C cable on a 2021 Mk4.

There have been a number of discussions here if you search for them.

I’ve got my nextbase 322 connected via the socket on a short cable. Works very well

Edited 10 March10 Mar by tich1958

Thanks both for the info.

Sounds as if I’m good to go!

1 hour ago, ChubbsH said:

Thanks both for the info.

Sounds as if I’m good to go!

Just to put a spanner in the works, If you are using just a single camera you might be fine, but if you are thinking of both front and rear I don't think the USB supplies enough power for both.

But to be honest connecting to the fuse box is not hard and its then just a matter of running the cable under the trim

Hi,

First time poster here.

I went through an ordeal while trying to power a dash cam from the USB-C port behind the rear-view mirror (Octavia MY25). I have a technical background and it still took quite a bit of troubleshooting, so I can see how someone less familiar with USB-C could run into issues and end up blaming the wrong thing.

So I figured I’d share what I learned in case it helps someone else, even if it's not directly answering the OP's question.

TL;DR

• The mirror USB-C port should have enough power for most dash cams (rated at 15 W, which is plenty).

• The USB-C ports in the FL Mk4 Octavias are USB-PD power sources, so if your dash cam understands USB-PD, any good USB-C cable should work

• But, if your dash cam has a USB-C power input and a USB-C <-> USB-C cable doesn’t work, try USB-C → USB-A adapter + USB-A → USB-C cable.

• If your dash cam uses Micro-USB, a USB-C -> Micro-USB cable should work without issues.

• Also keep in mind that the USB-C port — unlike using a hard-wire kit — is powered only when the car is on or in ACC (Accessory) mode.

The more detailed story

My Viofo A329S dash cam powers through USB-C, so I wanted to use the USB-C port instead of hard-wiring it.

I had a very short USB-C cable (~15 cm) lying around, so I decided to test with it. The camera powered up and worked normally.

But that cable was too short, so I tried a longer USB-C cable. That’s when things got weird:

• sometimes the camera would start normally

• other times it would play the startup chime, shut down, and repeat in a loop

At first I suspected voltage drop or insufficient power from the car.

So I connected a USB power tester to see what was actually happening.

The camera draws about 1 A at 5 V (~5 W) during operation (probably with a slightly higher spike during startup), which is well below the 15 W rating of that USB-C port. So power capacity was clearly not the issue.

Interestingly, the cable that was unreliable before worked flawlessly when connected through the power tester. That suggested the problem was related to USB-C signaling rather than power delivery itself.

What the actual problem seems to be

After spending some more money on various USB cables and adapters — and doing some additional research — the likely cause turned out to be USB-C protocol non-compliance on the dash cam side.

That dash cam does not implement USB-C Power Delivery (USB-PD). It simply expects 5 V power, similar to older USB devices.

With a USB-C <-> USB-C cable, the power source and device communicate via the CC (configuration channel) pins. The source expects to detect the correct pull-down resistor from the device to indicate that it’s a valid USB-C power sink. Some simple devices that just "expect 5 V" don’t fully implement this part of the USB-C specification.

When that happens, the power source may:

• delay enabling power

• repeatedly attempt to detect a valid sink

• briefly enable power and then shut it off again

From what I understand, that’s what causes the startup loop.

The workaround that fixed it

The reliable solution was: USB-C port -> USB-C-to-USB-A adapter -> USB-A-to-USB-C cable → dash cam

The USB-C → USB-A adapter contains the proper configuration resistor which tells the car’s USB-C port to behave like a legacy 5 V USB source.

Once that happens, the USB-A cable simply provides constant 5 V, without any USB-C negotiation involved, and the dash cam works perfectly.

Final note about cables

Some USB-C <-> USB-C cables might work depending on how they’re wired internally, but fully compliant cables (especially those with an e-marker chip) will expose the (potential) lack of proper USB-C signaling from the device and the camera won’t power reliably. However, USB-PD compliant dash cams should work with those cables (and probably only with those compliant cables).

So if your camera doesn’t start with USB-C <-> USB-C, don’t immediately assume the port lacks power — it’s often just a USB-C compatibility quirk.

And this issue generally only appears with USB-C <-> USB-C connections. Traditional USB-A connections simply provide 5 V power without USB-C negotiation, which is why the adapter workaround works.

My Viofo A129 is working fine with a 25cm USB-C --> Mini USB cable. It came with a rear camera, which was wired up in my previous car (Mazda 3 saloon/fastback) but isn't in my Octavia (estate), to avoid having to run a stupidly long cable. Instead, I've installed a Viofo A119 mini 2 at the back, which will be connected to the 12v socket, once a low battery voltage auto cutoff device (Rhundo RS-21S) arrives later today.

Edited 24 April24 Apr by davegr