How to Find Unresponsive Spots on a Touchscreen: A Trace Test and Common Causes
When part of the screen ignores your taps, or the phone starts pressing things by itself, the first step toward a repair or a support request is pinning down exactly where it happens. This guide explains how to find dead zones by tracing your finger over the whole screen, how to check multi-touch, what to rule out before deciding the panel is broken, and what to tell the repair shop.
Touchscreen problems fall into three types
"The touchscreen is acting up" can mean different things, and each points to different causes. Work out which of these matches your symptom first; it makes choosing the right checks much easier.
| Symptom | Common name | Likely causes |
|---|---|---|
| Taps don't register in one particular area | Dead zone, unresponsive spot | Cracked screen, internal connection fault, lifted screen protector |
| Things get pressed without you touching | Ghost touch | Noise while charging, water droplets, cracked screen, software bugs |
| The whole screen is slow or inaccurate | Poor sensitivity | Thick screen protector, gloves, a sluggish device |
With a dead zone, finding the exact spot narrows the cause down a lot. Ghost touch comes and goes depending on conditions, so it is important to note when it happens.
How to find dead zones by tracing the whole screen
In everyday apps you can't tell whether the parts of the screen without buttons are responding. If you divide the whole screen into a fine grid and color it in by tracing with your finger, only the unresponsive cells are left blank, so you can see the location at a glance.
- 1
Take off the case and dry your hands and the screen
If the edge of a case touches the screen or your fingers are damp, the result won't be accurate. Wipe your hands before you start.
- 2
Show the full-screen grid
Open Touch response in the Screen Checker and a grid fills the screen. Each cell is roughly the size of a fingertip.
- 3
Trace slowly from one edge
Go left to right from the top-left corner, then down one row at a time, like coloring in. Moving too fast can skip weak spots; about 2–3 seconds per row is a good pace.
- 4
Retrace any cells that are left
The checker shows where the uncolored cells are (top, bottom, left or right) and how many there are. Trace those spots several more times; if they still won't fill, treat them as unresponsive.
How many touch points should multi-touch detect?
Pinch-to-zoom, two-finger scrolling and simultaneous taps in rhythm games all need the screen to recognize several fingers at once. The Screen Checker counts the fingers on the screen and records the maximum number of points detected at the same time.
- Everyday use: if 2 points (a pinch) work reliably, normal use won't be a problem.
- When buying new or used: most recent phones and tablets support 5 or more points. Put five fingers down together and check that it shows 5.
- For games: count how many fingers you use across both hands and check that many register.
Some operating systems assign three- or four-finger gestures (such as undo or switching apps), and those may fire the moment your fingers land. If the count comes out low, gently place your fingers down together again and recheck.
What to rule out before deciding it's broken
Finding an unresponsive spot doesn't necessarily mean the hardware is faulty. Try these in order; sometimes they fix the problem without a repair.
- Remove the screen protector or glass: lifted edges, bubbles or a protector that is too thick can weaken response in just that area. Run the same test without it to compare.
- Unplug the charger: if ghost touch happens only while charging, noise from the charger or cable may be the cause. Compare with the original charger or a different one.
- Wipe moisture off the screen and your fingers: water drops and sweat can register as touches where you aren't touching. This is common in bathrooms and kitchens.
- Restart and update the OS: a software glitch can stop touch from responding. Restart and run the same test again.
If the same cells still fail after all of these, or the screen has a crack, a panel fault is likely. Even small cracks can reach the sensor layer underneath, so it is best to get it looked at before it gets worse.
What to tell the repair shop or support
The more specific you are, the faster the diagnosis. Note the following so you can pass on your test results directly.
- Where it doesn't respond (for example, lower right, about three cells across) and a screenshot of the test screen
- When it happens (only while charging, only with the case on, all the time, etc.)
- How many simultaneous touch points registered
- Anything that might explain it, such as a drop or water exposure
The Screen Checker's Copy results button gives you a text summary of the touch response rate and the number of simultaneous touches to paste into a message. If you are checking a secondhand device, look for dead pixels and burn-in at the same time; see checking a used phone's screen for the steps and how to check for dead pixels for what to look for.
FAQ
- How do I find the unresponsive spots on my touchscreen?
- Show a grid covering the whole screen and color it in by tracing with your finger. Any cells left uncolored are the unresponsive spots. Take off the case, dry your hands and trace slowly one row at a time.
- What causes ghost touch?
- Noise from the charger or cable, water on the screen, a lifted screen protector, a cracked screen or software bugs. Unplug the charger, wipe the screen, remove the protector and restart, in that order, to narrow it down.
- How many multi-touch points is normal?
- Two points are enough for everyday use. Most recent phones and tablets support 5 or more, so when buying, put five fingers down at once and check that it shows 5.
- Is it broken if only the edges don't respond?
- Phone screen edges are used for gestures like opening notifications or going back, so test cells there may not fill. Trace along the edge vertically or horizontally; if it still doesn't respond, suspect a fault.
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