MAPIWhy Are There Horizontal or Vertical Lines on My TV?
Straight lines are useful because their behavior can reveal where they originate. A line tied to one source is different from a fixed line that appears over every input and the TV's own test screen.
If the lines disappear when you change content or open the TV menu, the source or connection is more likely. If the same lines remain in the TV's Picture Test, the TV itself becomes the stronger suspect.
Key takeaways
- Lines that change with content can come from the source, aspect ratio, or HDMI path.
- A damaged or loose HDMI cable can introduce picture artifacts.
- Fixed lines in the TV's own test screen point more strongly to internal hardware.
- The same symptom across every input is more concerning than a source-specific line.
What it actually means
Horizontal or vertical TV lines are persistent or intermittent bands, rows, columns, or streaks that overlay the displayed picture.
The main explanation
LG's current guidance says lines, dots, or marks may be caused by the broadcast signal, aspect ratio, or connected cable and recommends screen self-diagnosis to decide whether the TV is involved. A reliable diagnosis therefore watches what the line does: if it disappears in menus or self-test, inspect the source; if it remains fixed in the same location across sources and internal tests, panel or internal electronics become more likely.
Main causes and reasons
1. The broadcast or external source contains the artifact
A source device or signal can send an image that already contains lines.
How to recognize it
- Lines appear on one channel or device
- TV menus are normal
- Another source is clean
Why it matters: The TV cannot remove an artifact that exists in the incoming video.
2. The HDMI cable or connection is unstable
A loose or damaged digital connection can produce visual artifacts.
How to recognize it
- Reseating the cable changes the lines
- Another cable fixes the problem
- Only one HDMI input is affected
Why it matters: LG specifically recommends checking HDMI when lines or marks appear.
3. Aspect or picture settings are distorting the image
An unsuitable aspect ratio or processing mode can create edge or scaling artifacts.
How to recognize it
- Changing aspect ratio changes the symptom
- The artifact appears only with one source format
- A picture reset helps
Why it matters: Settings are more likely when the line moves or changes with picture format.
4. The TV panel or internal electronics have a fault
Panel row/column drivers or internal circuitry can create fixed lines independent of source.
How to recognize it
- The line stays in exactly the same place
- It appears in Picture Test
- It persists with all cables and sources
Why it matters: A fixed line in internal diagnostics is strong TV-side evidence.
How to identify your situation
The incoming source is more likely.
Next: Test another source and cable before pursuing TV repair.
The panel can display the menu normally, so the source image is suspect.
Next: Investigate the set-top box, app, broadcast, or cable.
The TV's internal display path is likely involved.
Next: Use manufacturer service or warranty guidance.
The old cable or connection was the likely cause.
Next: Keep the known-good cable and inspect ports for damage.
What you can do
- Open the TV menu and see whether the line overlays it.
- Compare live TV, a built-in app, and an HDMI source.
- Reseat and replace the HDMI cable if the problem is source-specific.
- Return aspect ratio and picture settings to standard values.
- Run Picture Test or screen self-diagnosis.
- Restart and update the TV and connected device.
- Document fixed lines with photos before requesting service.
Common misconceptions
Source and cable problems can create similar artifacts.
Channel-specific lines are more likely to come from the source signal.
A fixed internal-test line can indicate a panel or electronics issue even when it is narrow.
When it may be a bigger problem
Contact the manufacturer if lines appear in Picture Test, remain fixed across all sources, grow over time, or are associated with impact damage, liquid exposure, half-screen failure, or other persistent panel defects.
Frequently asked questions
Can an HDMI cable cause lines on a TV?
Yes. LG recommends checking HDMI because a poor connection can create lines or other picture artifacts.
What if the lines disappear in the TV menu?
That suggests the source image or connected device is more likely than a fixed panel defect.
Do fixed vertical lines mean panel damage?
They can, especially if they appear in the TV's own diagnostic image and across every source.
Can aspect ratio cause screen lines?
LG notes that an unsuitable aspect setting can contribute to line or distortion symptoms.
Sources
- How to Fix Lines or Dots on Your LG TV Screen — LG SupportOfficial
- LG TV - How to Perform a Picture Test — LG SupportOfficial
Written by Mapiance Editorial Team
The Mapiance Editorial Team researches, writes, reviews, and maintains practical guides and explainers for MAPIANCE.
Reviewed by Mapiance Editorial Team
Published Sep 8, 2026 · Updated Sep 26, 2026 · Verified Sep 4, 2026