LG C2/C3 shows "No Signal": fixes that stick
LG's C2/C3 sets are great for 4K120, VRR, and gaming, but the extra bandwidth means a flaky cable or mislabeled port will black out faster than on older TVs. This guide focuses on C-series quirks: making sure HDMI Deep Color is on for the right ports, keeping consoles on HDMI 1–4 (all 2.1), and taming Game Optimizer/VRR when a handshake stalls.
Quick checks to rule out simple issues
- Confirm the correct input
On the Quick Input list, verify the console/PC icon sits on the port you're using. If the label is wrong, rename it so you know which HDMI 2.1 port you're actually on. - Inspect the HDMI cable
Look for sharp bends, kinks, or loose connectors. Use a certified Ultra High Speed cable for 4K120/VRR and reseat both ends until they click. - Test another HDMI source or display
If you can, plug a known-working device (like a streaming stick) into the same port, or plug your source into a different TV. This quickly tells you which side is misbehaving. - Restart everything
Power off the TV, the source device, and any receiver in between. Unplug them for 30 seconds before turning them back on.
Rebuild the HDMI connection step by step
- Start with a direct connection
If you normally run through a receiver or soundbar, temporarily connect the source straight to the TV with a short HDMI 2.1 cable. This removes one variable while you troubleshoot. - Confirm the right port for 4K120/VRR
All four HDMI ports on C2/C3 are 2.1, but HDMI 2 also carries eARC. If eARC is enabled, keep the console on 1, 3, or 4 to avoid audio handshakes stepping on VRR tests. - Toggle Deep Color and Game Optimizer
In Settings → General → External Devices → HDMI Input Format, set the active port to 4K. If the screen is still black, turn off VRR/Game Optimizer, get a stable 4K60 picture, then re-enable VRR. - Match resolution and refresh rate
Start at 4K60. If that works, bump to 120 Hz, then enable VRR/ALLM. If 120 Hz fails, try 1440p120 to rule out bandwidth or cable issues. - Power on in a clean order
Let WebOS finish booting, then power the receiver (if used), then the console/PC. C-series sets can cache EDID differently depending on that order.
Expert tip: try a different HDMI cable, even if the old one “used to work”
Tip: A surprising number of no-signal problems end up being a marginal HDMI cable that only fails at 4K or at higher frame rates. Swapping to a short, certified Ultra High Speed HDMI cable is one of the fastest ways to tell whether you are chasing a wiring problem or a device issue.
Gaming-ready cable pick for C2/C3
Scenario example
Scenario example: A PS5 on HDMI 4 worked at 4K60, but after enabling 120 Hz + VRR the screen went black. Moving the PS5 to HDMI 3 with a certified 2.1 cable, disabling VRR to get picture, then re-enabling VRR inside Game Optimizer keeps 4K120 stable. Leaving the eARC soundbar on HDMI 2 avoids extra handshakes on the console input.
When to suspect the TV, source device, or receiver
- Source device problem – If the TV shows “No signal” no matter which port you try, but other devices work fine in the same port, the console or streamer may be at fault.
- TV problem – If multiple inputs intermittently lose signal for every device, check for a TV firmware update and consider a full factory reset after backing up your picture settings.
- Receiver or switch problem – If things only fail when a receiver or HDMI switch is in the chain, connect the source directly to the TV. If that works, review the receiver’s video pass‑through and 4K/8K settings.
If you still cannot get a picture
After verifying cables, ports, and basic resolution settings, persistent "No signal" or black-screen behavior usually points to a failing port or a deeper compatibility issue. Document which combinations of source, port, and cable work or fail. Having that matrix ready makes support with LG or your TV manufacturer far more effective and can help justify a warranty repair or replacement when simple fixes are exhausted.
If you want a brand-agnostic HDMI checklist, see our full HDMI “No signal” guide at /posts/4k-tv-receiver-hdmi-no-signal-checklist.