When you replace the screen on an iPhone 4 there is a chance the proximity sensor will not work properly once you install the new screen, particularly if it’s a different color screen.
The issue is specific to the iPhone 4 and not because of how the screen was replaced. One of the reasons may be caused by the foam that surrounds the ambient light sensor and proximity sensor.
Based on the photo above, the ambient light sensor is the one on the left, and the proximity sensor is the one on the right. The ambient light sensor is used to detect the light levels in your surrounding. The proximity sensor is what disables the screen when you put your phone close to your ear.
Usually the foam will stick to the back of the broken screen, so once that’s removed the proximity sensor will not work properly as intended. Thankfully there are a few possible fixes to this annoying issue:
1. Full iOS restore – this is a software fix that works for some. Remember – do it safely to avoid losing your jailbreak and unlock.
2. Black marker pen – Use a permanent black marker and color the back side of the proximity sensor window on the iPhone 4 Screen. You may need to apply a few layers. This method works most of the time especially on the older iPhone 4 models.
3. Proximity sensor lens – This is a tiny lens that you place over the proximity sensor before you install a brand new screen. It looks like a contact lens that changes color according to the surrounding lights. We’ll make these available in our online store soon.
4. Foam – Try to replace the broken foam that was damaged during removal of your broken screen. Some people said using black electrical tape works for them.
What’s important is to have something in between the sensors to make sure they are not interfering with each other.
I hope these tips helped getting your proximity sensor working again!
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