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.