The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →A vertical line that remains in your LG TV’s built-in Picture Test is a television-side fault that warrants inspection. If the test image is clean, the panel is less likely to be the cause: isolate the HDMI or antenna cable, external device, broadcast signal, and picture settings first. This split prevents you from buying a panel or booking service for a problem caused by a source device.
Use this order: run the internal test, disconnect and reconnect every external signal, try another HDMI cable, correct the aspect ratio, disable HDMI Deep Color when the connected device is incompatible, and—on OLED models only—run Pixel Cleaning after those checks. Then document the symptom and ask LG or an authorized provider about warranty coverage if the line still appears in the test image.
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What a vertical line on an LG TV actually tells you
A stripe can be green, white, black, or another color, but its appearance alone does not identify the failed part. The decisive observation is whether the line is visible in an image generated by the television itself. LG’s Screen Self-Diagnosis or Picture Test removes the set-top box, console, streaming player, broadcast feed, and HDMI signal from the equation.
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If the line appears in that internal test, LG’s guidance is that the TV may need inspection. That does not establish a universal repair outcome: the cited LG support material publishes no single repair price, repair-time promise, success rate, or prevalence figure for vertical-line failures. If the test is clean, the fault is more likely to be an external source, cable, signal, or configuration.
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| What you see | Most useful interpretation | Next action |
|---|---|---|
| Line appears in Picture Test or Screen Self-Diagnosis | TV-side fault is more likely; software maintenance may help only in limited OLED cases | Complete the basic checks, then arrange LG or authorized inspection |
| Picture Test is clean, but one HDMI input shows the line | Connected device, HDMI cable, port, or input-specific setting is more likely | Reconnect, substitute the cable, test another device or input, and review HDMI Deep Color |
| Picture Test and LG home screen are clean, but a broadcast or app shows the line | Source device, broadcast signal, app output, or network-streamed video is more likely | Test the source independently and contact its provider if the defect follows that source |
| Line hugs an edge only after changing display format | Aspect-ratio processing may be drawing an edge artifact | Set Aspect Ratio to 16:9 or Original and retest |
| OLED line or stain changes after Pixel Cleaning | Uniformity or image-retention behavior may have contributed | Record the result; persistent lines still require service evaluation |
Step 1: Run LG’s internal Picture Test
Do this before replacing hardware. The menu path depends on webOS generation and model. Menu wording can vary by country, but these are LG’s published routes:
- webOS 6.0 and later, generally 2021 and newer: open Settings > All Settings > Support > Screen Self-Diagnosis.
- 2020 models using webOS 5.0: open Settings > All Settings > Support > Additional Settings > Picture Test.
- webOS 4.5 and earlier: open Settings > All Settings > Picture > Picture Test.
Start the test and inspect every part of the displayed pattern. Look for a line that stays in the same physical column while the test changes, not merely a transient pattern in the image. LG states: “If the lines or dots also appear in the test image, your TV may need to be inspected.” This statement is the service threshold, not a guarantee that a panel replacement is required.
If the test image contains the line
Photograph the test screen before changing settings. A clear, full-screen image helps a support agent distinguish a fixed column from a source artifact. Finish the cable, aspect-ratio, and input checks below, because a loose connection can sometimes be mistaken for a set fault. If the line remains in the test, stop treating it as an HDMI-only issue and prepare a service case.
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If the test image is normal
Press Home and inspect the LG launcher. Then repeat the check on a second input, such as a different HDMI port or an over-the-air channel if you use an antenna. A clean test and clean home screen strongly shift attention to the external device, cable, channel feed, or app. Note exactly which input produces the line; “only HDMI 2” is more useful to a technician than “sometimes.”
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Step 2: Isolate cables, ports, and external equipment
Power the TV off before moving connections. Disconnect the antenna lead and every HDMI cable. Examine both plugs and the TV ports under good light. Look for a bent center contact, crushed strain relief, cracked housing, looseness, or a connector that will not seat squarely. LG identifies loose or damaged HDMI and antenna cables as possible causes of visual noise and lines.
- With the TV off, remove all antenna and HDMI connections.
- Inspect each cable end and the corresponding port for visible damage or debris. Do not force a plug into a port that appears misaligned.
- Reconnect only one source, pushing the connector fully home without twisting it.
- Turn on the TV and check the source, the LG home screen, and the internal test again.
- If the line returns on that source, repeat with another HDMI port and a known-good spare cable.
- Reconnect the remaining devices one at a time. The first device or cable that brings the line back is the strongest lead.
A replacement high-speed HDMI cable is a reasonable diagnostic purchase when the existing cable is suspect. It is an isolation tool, not a guaranteed repair for a panel or internal display fault. Keep the original cable labeled so you can reproduce the symptom for support if needed.
Test the external device separately
Use the suspect console, set-top box, or streaming player on another display if one is available. Alternatively, connect a known-good device to the LG TV using the same port and cable. If the line follows the original device, investigate its output resolution, firmware, or connector. If every device produces the line on one TV input while the Picture Test remains clean, the port or input setting deserves attention.
Do not overlook an antenna or broadcast fault
A line that appears only on live television can originate in the antenna path or the broadcast signal. Check another channel and, if possible, another antenna lead. Streaming apps and recorded content provide additional comparisons: a clean app image with a defective broadcast channel points away from the panel.
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Step 3: Correct aspect ratio and HDMI settings
Set Aspect Ratio to 16:9 or Original
Open the picture controls while viewing the affected source and set Aspect Ratio to 16:9 or Original. LG notes that an incorrect ratio can draw lines along the screen edges. Retest the same content after each change. Do not judge the result from a single channel logo or letterbox bar; use a full-screen scene and the TV’s home screen as references.
If the line disappears only after changing the ratio, the display panel may be functioning normally and the previous scaling mode was producing the edge artifact. Leave the setting that preserves the source’s intended geometry rather than repeatedly switching modes while diagnosing.
Check HDMI Deep Color on the affected input
When the line occurs on one HDMI input, review that input’s HDMI Deep Color setting in the TV’s picture or input options. LG associates incompatibility between this mode and a connected device with lines, flicker, and color distortion. Turn HDMI Deep Color off for that input when the device does not support it, then power-cycle the source and retest.
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Step 4: OLED-only Pixel Cleaning
Pixel Cleaning is relevant only to LG OLED televisions. First run Picture Test and check external connections. If a line or stain remains in the test image or across multiple channels, open the OLED maintenance area—usually labeled OLED Care or OLED Panel Care—and select Pixel Cleaning. Older webOS versions may call the same type of routine Pixel Refresher.
Follow the on-screen confirmation and leave the television plugged in. LG explains that the routine can be scheduled to run after the TV powers off, so disconnecting power immediately can prevent completion. Allow the set to finish its own cycle before judging the result.
Pixel Cleaning is designed for panel uniformity and image-retention-type behavior. It is not evidence that software can repair a mechanically damaged panel, a failed drive circuit, or a permanent column defect. If the same fixed line remains after the routine, record that outcome and proceed to service rather than repeating maintenance indefinitely.
Why LCD, LED, and QNED owners should not use OLED instructions
LCD, LED-backlit LCD, and QNED models do not use the OLED Pixel Cleaning routine described above. Their troubleshooting path is the internal test, signal isolation, cable substitution, aspect-ratio correction, and service evaluation when the line is present in the TV-generated image. Do not select an OLED maintenance option that your model does not provide.
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Diagnose the symptom by where and when it appears
| Pattern | What it suggests | Checks that discriminate the cause |
|---|---|---|
| One HDMI input only | Source device, cable, port, or HDMI Deep Color compatibility | Use a spare high-speed HDMI cable, a different port, and another device; disable HDMI Deep Color for the affected input if unsupported |
| All HDMI devices, but not the LG home screen | Common cable, configuration, or signal-handling issue | Test each device separately, compare ports, and verify Aspect Ratio |
| One broadcast channel only | Channel feed, antenna lead, or reception problem | Try other channels and another antenna cable; compare with an app or local media source |
| Every input and the home screen, but Picture Test is clean | Intermittent connection, input processing, or condition that changes with content | Photograph the line, repeat after a cold power cycle, and test a second source while the line is visible |
| Picture Test also shows the line | TV-side hardware or panel path is more likely | Complete basic checks once, then contact LG or an authorized provider |
| OLED line or stain improves after Pixel Cleaning | Uniformity or retention-related behavior may be involved | Monitor recurrence; service is still appropriate if a fixed line returns or persists |
When to stop troubleshooting and request service
Arrange an LG support case or authorized inspection when the line remains in Picture Test after you have checked connections, tried a spare cable, corrected Aspect Ratio, and addressed HDMI Deep Color compatibility. A line that is visible on the test pattern is not something an external streaming subscription or computer repair utility can fix.
Warranty and service availability depend on your country, model, purchase date, and the terms attached to that sale. Ask about coverage before authorizing a panel replacement. LG’s cited guidance does not publish a universal price, repair-time promise, or success-rate statistic, so any quote or turnaround supplied to you is specific to your region and case.
Prepare the information a technician needs
- Model number and serial number from the rear label or TV information menu.
- Purchase date and proof of purchase if available.
- A full-screen photograph showing the line and a second photograph of the Picture Test result.
- Whether the line is vertical, its color, approximate width, and whether it is fixed in one column.
- Every input and source tested, including whether the LG home screen and internal test are affected.
- The HDMI cable and port substitutions you tried.
- For OLED models, whether Pixel Cleaning or the older Pixel Refresher changed the symptom.
Keep the TV accessible and do not open the rear cover. Internal display circuits can retain hazardous voltage, and opening the set can affect warranty eligibility. A service professional can determine whether the practical remedy is a board-level repair, panel replacement, or replacement of the television; the support pages do not establish that outcome in advance.
Quick Recap
Common mistakes that make a line diagnosis harder
- Replacing the panel before running Picture Test: a source or cable fault can look identical during normal viewing.
- Changing several settings at once: you lose the ability to identify which setting affected the line. Change one item, retest, and record the result.
- Testing only a single app: app video can hide a defect that appears on another input, or create a source-specific artifact.
- Unplugging an OLED during Pixel Cleaning: the scheduled maintenance may not complete.
- Assuming a new HDMI cable guarantees a repair: it can rule out a cable, but it cannot restore a failed panel column.
- Relying on color as a diagnosis: green, white, and black stripes can all require the same Picture Test decision.
A practical decision checklist
- Display LG’s Picture Test or Screen Self-Diagnosis using the menu path for your webOS version.
- If the pattern is clean, check the LG home screen and another input to locate the source of the artifact.
- Power off, disconnect antenna and HDMI leads, inspect the connectors and ports, and reconnect one source at a time.
- Try a known-good high-speed HDMI cable and a different HDMI port.
- Set Aspect Ratio to 16:9 or Original.
- For a single HDMI input, disable HDMI Deep Color when the connected device is incompatible, then retest.
- On OLED models only, run Pixel Cleaning—or Pixel Refresher on older webOS versions—after the preceding checks and leave the TV plugged in.
- If the line still appears in the TV-generated test image, photograph the result, gather model and purchase details, and request LG or authorized inspection.
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