My CEC Adapter Isn’t Working — Where Do I Start?

This article helps you identify what's wrong and points you to the right fix. Work through the checks below in order — most issues are resolved by step 3.

Step 1 — Check the Physical Connection

Step 2 — Confirm libCEC is Installed

All Pulse-Eight CEC adapters require libCEC to be installed on the host PC. If it has never been installed, or was installed incorrectly, no CEC commands will work.

→ How to Install libCEC (Windows)

Step 3 — Confirm CEC is Enabled on Your TV

HDMI-CEC must be switched on in your TV's settings menu. Every manufacturer uses a different name for this feature:

Consult your TV's settings menu and ensure the feature above is enabled. On some models it is off by default.

Step 4 — Identify Your Specific Symptom

If the adapter is connected, libCEC is installed, and CEC is enabled on the TV but something still isn't right, find your symptom below:

The adapter is not detected / CEC-Tray shows no adapter

• Check Device Manager for a Pulse Eight CEC Adapter entry under Ports (COM & LPT). If it appears with a warning icon, reinstall libCEC.
• Try a different USB port on the PC.
• Confirm the firmware is up to date — an older firmware version can cause detection failures.

→ Upgrading the Firmware of the CEC Adapter

The TV won't turn on when the PC boots

• This requires firmware v9 or newer and a correctly configured power-on method.
• The USB port must lose power when the PC shuts down — if it stays powered, the adapter cannot detect the boot event. Disable USB charging / USB power in S5 in your BIOS if needed.

→ Which TV Power Control Method Should I Use?

→ How to Turn Your TV On at Boot Using CEC-Tray

→ How to Turn Your TV On at Boot Using a Windows Batch Script

CEC-Tray won't open or throws a DLL error

• This is almost always caused by copying the CEC-Tray executable to another location instead of creating a shortcut. The executable depends on DLLs in the same folder and will fail if moved.
• Delete any copied executable and create a shortcut to the original instead.

If a full reinstall is needed: → How to Install libCEC (Windows)

The TV turns on but the PC also wakes from sleep unexpectedly

→ CEC Adapter — Using the LibCEC Standby Monitor

The TV goes to standby when the PC's screensaver activates

This is the screensaver / inactivity standby feature in CEC-Tray. If you want to disable it, open CEC-Tray, go to the Power Control tab, and set the standby delay to Off.

→ CEC Adapter Screensaver / Inactivity Standby

Panasonic TV media control buttons are not working

→ Panasonic TVs — Media Control Buttons Not Working with CEC Adapter

I'm on an LG TV and CEC stopped working after a firmware update

There is a known issue with LG WebOS 4.0 (software version 05.10.25, released November 2019) where CEC stops working on HDMI 2 (the ARC port). Connect your device to HDMI 1 instead.

→ NUC CEC Issue — LG WebOS 4.0 (SW Version 05.10.25, November 2019)

I'm not sure which adapter or method is right for my setup

→ Which TV Power Control Method Should I Use?

→ Intel NUC CEC Adapters — Hardware Compatibility and Legacy Notice

Hardware Setup Guides

If you are installing or reinstalling an Intel NUC CEC Adapter, use the guide for your NUC generation:

• 4th Gen NUC — Cable Harness Installation
• 5th Gen NUC — Cable Harness Installation
• 6th / 7th / 8th Gen NUC — Cable Harness Installation
• Skull Canyon NUC — CEC Adapter Installation
• Hades Canyon NUC — CEC Adapter Installation

Related Articles

• Getting Started with the Pulse-Eight USB-CEC Adapter
• How to Install libCEC (Windows)
• Upgrading the Firmware of the CEC Adapter
• Which TV Power Control Method Should I Use?
• Intel NUC CEC Adapters — Hardware Compatibility and Legacy Notice