Loathe as some are to admit, some back story is helpful to explain the full extent of any issue. This one in particular is more complex than meets the eye. If you want to get straight to the part of the page where we get to triage, skip past the next section straight to the "First Repair Steps."
Note: If at any time your display exhibits grey pixelated bars along its top edge followed by non-responsive or intermittent touch, this is the hallmark symptom of the board fault, Read the following intro if you're interested, then skip ahead to the Faulty Logic Board section.
The Fault - An Engineering Mishap
When Apple released the iPhone 6 and iPhone 6 Plus, they introduced a whole new design for their signature smartphone. The biggest notable change (pun definitely intended) being its larger form factor.
This increase in size came with additional reinforcement complications. Shoving your new iPhone 6 Plus in your back pocket might incur a noticeable bend in the housing, a phenomenon known in the media as "Bendgate."
Unintentional chassis flexibility, coupled with poor placement of touch related board components, commonly leads to multitouch issues unrelated to the device's display. Even minor, gradual bends or drops can do more damage than aesthetic imperfection—leaving your touch screen unresponsive or intermittently functional.
Even though it's possible the issue relates to the board, it's important to rule out other potential causes. Before undertaking any of the more time consuming solutions below, these are a few fundamentals to get you started.
- Perform a force restart. This could clear any minor software hiccups.
- Clean and dry the screen, as well as your hands. Modern touch screens are reliant on your skin’s natural electrically conductive properties. If the screen, or your hands have substances on them that change these characteristics, your touch screen may behave erratically or not work at all.
- Remove any screen protectors or cases. They may impede proper electrical interactivity with the display.
Any software which contains errors can cause an iPhone to act unpredictably. It can even cause the phone to think an area is constantly being touched.
- See if touch works properly on the home screen. Ask Siri to “Go to the home screen,” if necessary.
- If touch on the home screen works, open the App Switcher and close the app(s) where the issue occurred.
- Reopen the affected app and try to recreate the issue. If it reoccurs, check the App Store for updates and install them. Uninstall and reinstall the app if no updates are present.
- If the home screen is also behaving unpredictably, this is more likely a hardware issue, but you can update your phone to be certain.
- To rule out software entirely, be sure you have a current backup, and restore your phone using the recovery mode method. This will delete all data on the phone. Set the device up without restoring any of your data to test. This will ensure no third party apps are responsible.
Although most display failures seem obvious, even without visible damage, the display may not work properly due to something amiss internally.
- Look closely at your phone for signs of damage. Minor cracks in the screen or bends in the housing are often responsible for touch problems. Changing your viewing angle helps to catch small hairline cracks. Note: Even if damage has been present for some time, a small shift in an existing crack could affect functionality.
- Recently replaced your screen? The new display may be faulty. Third party replacements are of variable quality. Issues with touch functionality are rampant in low grade parts. Contact the shop which performed the replacement or the vendor you bought the display from and ask about warranty.
- If you find damage, or software fixes have not made a difference, replace the display. Parts and tools to do this can be found at the iFixit Store.
Faulty Touch Controller
There are two Integrated Circuits, more commonly known as ICs or chips, that can cause this fault, although one is more common. Both are located on the rear of the logic board in an area especially prone to flexion—even during normal use. Due to this flexion, the connection between the IC and the board can be totally or intermittently severed, leading to this failure in touch.
- If your device exhibits gray lines or squares at the top of the display, especially when touch is unresponsive, this is the hallmark indicator of this problem.
- This could also manifest as slow or intermittent touch response.
- To determine if your phone is affected by this issue you can try to force its appearance.
- Firmly hold the phone at the bottom with your right hand.
- With your left hand, grip the top edge. Your thumb should be positioned horizontally across the ear speaker and front camera.
- Use your left hand to gently twist the phone in every direction.
- If this creates the issue, the touch controller is to blame.
- If this resolves non-functional touch, this also confirms an IC issue.
- To fix this problem, you'll need microsoldering skills, specifically the ability to solder BGA (ball grid array) chips. If this is outside your current skillset, any independent repair tech who works on iPhone boards should be able fix this issue due to its prevalence. See if this is something your local shop can do!
Other Logic Board Fault
The logic board is the hub for the vast majority of an iPhone's functionality. Any number of the small components on the board may have failed or become damaged, and is a safe assumption of cause if nothing else on this page has worked.
- Check for obvious signs of a board issue - burned or cracked components, liquid residue, corrosion or bend. If there are signs of liquid the iPhone Liquid Damage Guide might help.
- Replacing the logic board is often the most practical solution for a DIYer with a faulty logic board.
- Contrary to popular belief, the board itself can be repaired. However, it requires specialized tools and microsoldering know-how. This is not something most people can do themselves, but many independent repair shops can do it for you! Ask around to find board level repair specialists near you.