Lines, dots, or marks on your LG TV screen may be caused by the broadcast signal or a connected cable. Set the aspect ratio to 16:9, and check the HDMI cable connection. You can also run Screen Self-Diagnosis to check whether the issue may be related to the TV.
Why Are There Lines, Dots, or Marks on the Screen?
If the lines, dots, or marks disappear when the screen content changes or when you open a menu with the remote control, the issue is likely not related to the TV panel. This usually occurs when the signal from the set-top box is unstable, the aspect ratio is set incorrectly, or the HDMI cable is damaged.
How to Fix Lines, Dots, or Marks on Your LG TV Screen
1. Change the Aspect Ratio to 16:9
An incorrect aspect ratio may distort the picture or cause lines to appear. Change the aspect ratio to the standard 16:9 setting.
For 2024–2026 Models- 1. Press the Settings button (gear icon) on the remote control.
- 2. Select All Settings from the quick menu.
- 3. Select Picture, then Aspect Ratio.
- 4. Select User Selection, then 16:9.
Press the Settings button on the remote, and select: All Settings, Picture, Aspect Ratio Settings, Aspect Ratio.
2. Check the Antenna and HDMI Cable Connections
A loose or damaged cable may cause picture noise or other display issues.
- 1. Make sure the antenna cable is securely connected to the back of the TV.
- 2. Disconnect and securely reconnect the HDMI cable between the TV and the set-top box.
- 3. Try using a different HDMI cable to see if the original cable is faulty.
3. Run Screen Self-Diagnosis
Screen Self-Diagnosis (also called Picture Test on some models) helps you determine whether the issue is with the TV or an external device, such as a set-top box.
For 2024–2026 Models- 1. Press the Settings button on the remote control.
- 2. Select All Settings.
- 3. Select Support, then Screen Self-Diagnosis.
- 4. Check the test screen for lines, dots, or marks.
If no lines or dots appear on the test screen, the issue may be related to the set-top box or input signal rather than the TV. Contact your set-top box or internet service provider to check the broadcast signal.
For 2023 or Earlier Models- 2021–2023 Models: Press the Settings button on the remote, select All Settings, then Support, and choose Screen Self-Diagnosis.
- 2021–2023 OLED Models: Press the Settings button on the remote, select All Settings, then General, OLED Care, Device Self Care, and choose Screen Self-Diagnosis.
- 2020 Standard LED Models (webOS 5.0): Press the Settings button on the remote, select All Settings, then Support, Additional Settings, and choose Picture Test.
- 2019 or Earlier Standard LED Models (webOS 4.5 or earlier): Press the Settings button on the remote, select All Settings, then Picture, and choose Picture Test.
4. Turn Off HDMI Ultra HD Deep Color for an Unsupported Device
HDMI Ultra HD Deep Color provides enhanced picture quality. However, picture issues may occur if an older set-top box or another connected device does not support this feature.
For 2021–2026 Models- 1. Press the Settings button on the remote and select All Settings.
- 2. Select General, then External Devices, and choose HDMI Settings.
- 3. Select the connected HDMI port and set HDMI Ultra HD Deep Color to Off.
5. Still Need Help?
If the issue persists after following the steps above, you can get further support through the LG Chatbot on the LG website or by scheduling a service. Note: A service fee may apply if your product is out of warranty.
- You can run Screen Self-Diagnosis only if the TV menu appears when you press the Settings button on the remote.
- Picture issues may occur if a connected device does not support HDMI Ultra HD Deep Color.
- Handle cables carefully. Pulling or bending them with excessive force can damage the TV's connection ports.
FAQ
- Q. What Should I Do If the Picture Test Looks Normal but Lines Still Appear?
- A. If the test screen looks normal, the issue is likely related to the set-top box or input signal rather than the TV. Try restarting your set-top box by unplugging its power cable for one minute, then plugging it back in. If the lines persist, contact your TV service provider to check the signal.
- Q. Do I Need a New HDMI Cable, and Which Type Should I Choose?
- A. If the issue disappears after you replace the cable, the original cable was likely damaged. When buying a new one, we recommend a certified HDMI 2.0 or HDMI 2.1 cable for stable 4K video transmission.
This guide is based on standard models. The settings menu may vary by model.
