Symptoms
- Cable charges slowly or not at all on a device that normally fast-charges
- Cable doesn't transfer files even though it's USB-C on both ends
- Cable works for charging but not for an external monitor
- Device shows an 'accessory not supported' type message
Likely causes
- CommonCable is charge-only, without data wiresMany cheap USB-C cables only carry power, not data or video signal.
- CommonCable can't handle the wattage the device needsFast charging and laptop charging require cables rated for higher power delivery.
- PossibleCable lacks the extra wiring needed for video (DisplayPort Alt Mode) or ThunderboltBasic USB-C cables won't carry a monitor signal even if they charge fine.
- PossibleDamaged or counterfeit cableCheap or fake cables sometimes lack proper shielding or components.
- Less commonPort on the device is faulty rather than the cableTest with another cable to rule this out.
What to do
- Check the cable's packaging or markings for its wattage rating and whether it supports data (often marked with a small icon).
- Test the cable for basic charging first, then for file transfer, then for video if relevant, to isolate what it actually supports.
- Try the cable on a different device to rule out a port problem.
- If you need fast charging or a monitor connection, buy a cable explicitly rated for USB Power Delivery or DisplayPort Alt Mode with the correct wattage.
- Avoid unbranded ultra-cheap cables for anything beyond basic slow charging.
Tools and parts
- None required
USB-C cable rated for data and fast chargingSearch: “USB-C 100W data cable”
USB-C to DisplayPort cableSearch: “USB-C DisplayPort Alt Mode cable”
When to call a pro
No professional needed; simply match the cable's rated capability to what you're trying to do.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.