A Dell XPS 14 9440 whose USB-C ports do not recognize a device, do not charge a phone or drop a connection has a question that depends on the device, the cable and the port's role, and a few tests separate them. This laptop has USB-C and Thunderbolt ports and no USB-A ports, so all peripherals connect through USB-C, an adapter or a dock. The same port can carry data, power and video, and a device may work for one of these and not another. First test the device and the cable together. Try the device in each port and on another computer, and try another cable, since many USB-C cables are charge-only or slow and some do not support data.
The checks in more detail
A flash drive, a mouse and a headset connect through data lines, a phone charges through power delivery, and a monitor needs DisplayPort. For an adapter or a dock, test it with another laptop. Restart with every accessory unplugged, then reconnect them in turn. Then Windows. Open Device Manager and look under Universal Serial Bus controllers and Thunderbolt for a device with a warning symbol; right-click and uninstall, then restart so Windows reinstalls it. In power settings, make sure that USB selective suspend is not turned on in a way that puts ports to sleep, and in the power plan on battery that devices are not being disconnected to save power.
Update Windows, and use Dell SupportAssist or Dell Command Update to install the Thunderbolt, chipset and USB drivers and the BIOS. Dell docks also have firmware that Dell's tools update. If a port is dead on every device, drain the power: shut down, unplug the charger, hold the power button for 20 seconds, then restart. Check the port with a flashlight for lint, which can be cleared carefully with a wooden pick. A port that is loose, bent or dead is a hardware fault that Dell's warranty can repair; quote the service tag. Remember that the XPS 14 charges over USB-C, so a faulty port also affects charging.
Because the XPS 14 has only USB-C and Thunderbolt ports, a hub is almost always part of the story. A cheap hub shares one port's bandwidth and power among everything attached, so a drive, a mouse and a display on one hub can drop out in turn. Use a powered hub or a Dell dock for several devices, keep high-speed drives on their own port and put a hub's cable on the port that the laptop's charger does not use. Windows may also show a message that a device can run faster in a different port, which is worth following. If the laptop warms up while a hub is attached, the hub's power draw may be the cause.
Differential
Likely causes of “Dell XPS 14 9440 USB or Thunderbolt device is not recognized”, and how to tell them apart
- 1
A charge-only or low-quality cable
What separates it The device charges but is not recognized
How to confirm Use a data cable
- 2
A faulty adapter or dock
What separates it The device works directly but not through the dock
How to confirm Test the dock elsewhere and update its firmware
- 3
A USB controller glitch
What separates it No device is recognized or it drops out
How to confirm Reinstall the controllers and restart
- 4
Power-saving settings
What separates it Devices disconnect on battery
How to confirm Adjust USB selective suspend
- 5
A damaged port
What separates it One port fails with every device
How to confirm Dell service
Before you touch a setting
Record this first — changing settings destroys the evidence
- Which ports and devices fail
- Whether the device works on another computer
- What cable and dock are used
- The service tag
Try in this order
0 of 6 completedTest device and cable
ReversibleOn another computer.
Test each port
ReversibleAnd the dock.
Restart with devices out
ReversibleAdd them one by one.
Reinstall USB controllers
ReversibleIn Device Manager.
Update drivers and BIOS
ReversibleSupportAssist.
Contact Dell
ReversibleIf a port is dead.
Model-specific
What is true of this model and not of its siblings
- One port, several jobs
- Data, power and video share a USB-C port.
- Cables
- A cable can lack data or video lines.
- Drivers
- Dell packages Thunderbolt and USB drivers.
- A power reset
- It clears a stuck controller.
- Docks
- They have firmware to update.
- Dell help
- Quote the service tag.
- Hubs
- They share one port's bandwidth and power.
- Port choice
- Keep fast drives on their own port.
Stop boundary
When this stops being a self-service repair
- !Do not force a plug into a port
- !Unplug the charger before a power reset
- !Contact Dell if a port is loose or dead
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why does my XPS 14 not see my USB device?+
The cable, the dock or a driver.
Does it have USB-A?+
No, only USB-C and Thunderbolt.
Can a port be repaired?+
Yes, under warranty.
Do I need a dock?+
For older devices, an adapter or dock.
Does charging use the same port?+
Yes.
Why do my devices drop out through a hub?+
A cheap hub shares bandwidth and power.
Should I use a dock?+
Yes, for several devices.