How to test a monitor before the warranty deadline

Your monitor warranty is nearly over, and you want to know whether that tiny spot, flicker, or uneven color is a real defect. A quick check now gives you time to repeat the test and contact the seller or manufacturer before the deadline.

Use the Display Test to check pixels, colors, and refresh rate. If you find a pixel that appears stuck on one color, the Stuck Pixel Fixer can try flashing it, but it cannot repair every pixel problem.

Test the monitor

1. Open the Display Test on the monitor you want to check. If you have several screens, make sure the test is showing on the one covered by the warranty.
2. Inspect the color tests closely for dots, lines, patches, flicker, or uneven areas. Look at the screen straight on, then check the edges. Use a clean, soft cloth to remove dust before treating a spot as a defect.
3. Check the monitor at its native resolution and a refresh rate it supports. Compare the system setting with the monitor's specifications or on-screen display. Look for flicker, brief blackouts, or an image that does not remain steady.
4. If one pixel stays bright or shows the same color across the test, open the Stuck Pixel Fixer on that screen. Use its flashing test briefly, then check the pixel again. Do not use flashing if it could trigger discomfort or a photosensitive reaction.

Repeat the inspection after the monitor has been on for about 20 minutes. If the symptom comes and goes, note when it appears, such as after waking from sleep or when the screen is set to a particular refresh rate.

What the result means

A dot stays bright or keeps one color

This may be a stuck pixel or subpixel, a tiny part of a pixel that remains lit. The Stuck Pixel Fixer may help in some cases, but a change after flashing does not guarantee the issue is permanently gone. Retest on solid colors and note whether the dot returns.

A dot stays dark across the color test

A dark dot may be a dead pixel, but first rule out dust or a mark on the surface. Clean the screen gently and view the same spot on different colors. If it remains in exactly the same place, record it as a possible panel defect.

You see a line, flicker, or large color patch

A whole row, column, or area behaving differently can point to a panel problem, but a cable or graphics issue can look similar. Check the connection and test another source before deciding the monitor itself is faulty.

The test looks normal

You did not reproduce a visible defect during this check. It does not prove the monitor will never fail, or that every feature works under every condition. If a problem appears only during a particular task, try to reproduce that task and record what happens.

The refresh rate is lower than expected

The monitor may be set to a lower rate, or the connected cable, adapter, port, or graphics device may limit the available choices. Check the monitor's supported modes and test a direct connection if possible.

How to check and rule out common causes

1. Clean the screen gently. Turn the monitor off and use a clean microfiber cloth. Do not press hard, scrape the panel, or spray cleaner directly onto it.
2. Reconnect the video cable. Unplug and firmly reconnect both ends. If possible, try another cable and another port, and select the matching input in the monitor's on-screen menu.
3. Set a supported resolution and refresh rate. On Windows 11, open Settings › System › Display, select the monitor, then open Advanced display. On macOS, open System Settings › Displays. Choose a mode supported by the monitor and connection, then repeat the test.
4. Test another source. Connect the monitor to another computer or device with a known-good cable. If the same spot or line remains in the same place, the monitor is a more likely cause than the original computer.
5. Restart the monitor and computer. Turn the monitor off, disconnect its power for about a minute, reconnect it, and restart the computer. This can clear a temporary signal or wake-from-sleep problem, but it will not fix a physical panel defect.

When to contact the seller or manufacturer

If a pixel defect, line, flicker, or patch remains after you have checked the cable and another source, contact the seller or manufacturer before the warranty ends. Pixel policies differ: some cover a single defective pixel, while others require a certain number or pattern of defects. Ask what evidence they need and whether opening a support case before the deadline preserves your claim.

Save the purchase date, model and serial number, a short description of the symptom, and clear photos or video showing the defect. A camera can create moiré patterns or flicker that are not visible to your eyes, so include the test conditions and do not treat a camera artifact alone as proof. Keep your warranty claim reference and follow the provider's instructions for any return or repair.

Do not press or rub a pixel to try to fix it. If the defect is still visible during normal use and the warranty may cover it, document it and ask for service rather than risking panel damage.