The situation when smartphone screen suddenly turns off at the most inopportune moment of a conversation is familiar to many Android users. You try to dial a number through contacts, press the speaker button, or open the dialer, but the display remains black and does not respond to touches. This is not just an annoying bug, but often the result of protective mechanisms that, under certain conditions, begin to function incorrectly.
The main culprit here is proximity sensor, which should turn off the backlight when the phone is brought to the ear to avoid accidental pressing with the cheek. However, if this sensor is dirty, covered with a protective film, or has a software glitch, the screen turns off immediately after starting a call and does not light up again. In this article we will analyze all possible causes and ways to eliminate them, from simple settings to deep calibration of the system.
It is important to understand that the problem can be both software and hardware in nature. Sometimes it is enough to simply wipe the upper part of the case, but in other cases it will be necessary to intervene in the engineering menu or replace components. Let's go through all the diagnostic steps one by one to return your device to normal operation.
Proximity sensor: principle of operation and main failures
The problem is based on the infrared sensor, usually located at the top of the display next to the earpiece. Its task is to measure the distance to an object. When you bring the phone to your head, the sensor detects the reflection of the IR beam and sends a signal to the system PROXIMITY_NEAR, after which the OS blocks the touchscreen and extinguishes the matrix. If the sensor “sees” the obstacle constantly, the screen will go out immediately.
A common cause of false alarms is simple contamination. Dust, finger grease, or adhesive residue from old film may block the sensor lens. Also, the problem often becomes low-quality protective glassesthat do not have a special cutout or have too high a density that distorts the passage of infrared radiation.
⚠️ Attention: Before starting any manipulations, make sure that there is no thick layer of dirt or residue on the top of the screen (above the display) glue. Even transparent dust can cause a failure.
Sometimes a failure occurs at the level of software signal processing. The operating system Android may incorrectly interpret data from the sensor after updating the firmware or installing a third-party launcher. In such cases, the sensor is physically working, but the logic of its operation is broken.
Try to gently wipe the upper frame of the smartphone with microfiber soaked in isopropyl alcohol. This often solves the problem of false alarms of the sensor.
Basic settings and cleaning of the sensor
The first step should always be physical cleaning and checking simple settings. You shouldn’t immediately go into complex menus if the problem is solved in a couple of seconds. Check to see if you have the “In Pocket” mode enabled or a similar feature in the manufacturer’s shell, which can aggressively block the screen.
It’s also worth paying attention to accessories. Cases with a magnetic fastener or thick bumpers that cover the top part can magnetize the Hall sensor or simply physically interfere with the operation of the proximity sensor. Remove the case and check the operation of the phone in its “naked” form.
If the problem persists, try a simple reboot of the device. This will clear temporary files and restart phone call services. In some cases, resetting the network settings helps, which does not affect your personal data, but updates the configuration of communication modules.
- 🧼 Carefully wipe the area above the screen with a soft cloth.
- 📱 Remove the protective glass or film to check.
- 🔄 Restart your smartphone to resetting temporary errors.
- 🧲 Remove the case, especially if it has a magnetic cover.
Calibrating the sensor through the engineering menu
If simple methods do not help, you need to proceed to calibration. This is the process where you force the system to know which values are considered “normal” and which are considered “approximations.” For this, hidden codes are used that open the engineering menu.
Enter the code ##7780## or #0# in the dialer (combinations may vary depending on the brand, for example, for Xiaomi it is ##6484##). You are interested in the section Proximity Sensor. Here you will see two values: Raw Data and State. Cover the sensor with your hand - the values should change.
The calibration menu usually has “Calibrate” or “Get Data” buttons. Press "Calibrate" without covering the sensor, then remove your hand and press "Calibrate" again. The system will remember the ranges. After completing the procedure, be sure to reboot the device.
⚠️ Attention: In the engineering menu, do not change settings that you are not sure about. Resetting other parameters may lead to unstable operation of the radio module or camera.
What to do if the codes do not work?
Some telecom operators block the entry of USSD codes into the call menu. Try typing the code without pressing the call button, or use third-party calibration applications from the Play Market, such as “Proximity Sensor Reset & Test”.
Settings depending on the smartphone brand
Different manufacturers make their own changes to Android, so the path to the settings may differ. Owners Samsung should check the settings through the Samsung Members application in the diagnostics section. Xiaomi i Redmi have a special CIT engineering menu, accessible by code ##6484##.
On devices Huawei i Honor it often helps to disable the “Phone Application” function in the battery settings so that the system does not limit its operation. Also, some EMUI shells have a separate “Proximity sensor” switch in the advanced call settings.
Below is a table with codes and paths for popular brands to make it easier for you to navigate:
| Brand | Test code | Path in settings | Feature |
|---|---|---|---|
| Samsung | #0# |
Settings -> Accessibility | There is a test in Samsung Members |
| Xiaomi | ##6484## |
CIT Menu -> Proximity Sensor | Need manual calibration |
| Huawei | ##2846579## |
ProjectMenu -> | Complex menu, required caution |
| Meizu | ##4636## |
Settings -> About phone -> Information | Frequent crashes after updates |
Each brand has its own unique set of codes and menus. Use the table above as a starting point, but remember that the paths may change on custom firmware.
Third-party applications for controlling the screen
When system tools are powerless, applications from Google Play come to the rescue. They can take over control of the sensor or offer alternative ways to lock the screen. One of the popular solutions is an application Proximity Sensor Resetthat programmatically resets the sensor state.
There are also applications that change the logic of the screen during a call. For example, they can disable the touchscreen lock, but leave the screen on, or use the accelerometer instead of the proximity sensor to determine the position of the phone.
However, you should be careful: installing third-party “dialers” or screen managers may conflict with the system Phone application. This may cause the screen to stop going dark altogether, which will lead to accidental ear presses during a conversation.
- 📲 Proximity Sensor Reset — for a soft reset.
- 📞 True Phone Dialer —an alternative dialer with its own settings.
- 🔧 Sensor Test — for deep diagnostics of all sensors.
- ⚙️ MacroDroid —to create your own blocking scenarios.
Hardware problems and repairs
If no software methods help, there is a high probability of physical breakdown. The proximity sensor could fail, the cable could come loose, or the contacts could oxidize. This often happens after the smartphone is dropped or gets wet.
In modern smartphones, the sensor is often built directly into the display module or glued to the cable. Replacing it may require disassembling the device and using special equipment. If the phone is under warranty, it is better to immediately contact the service center.
A temporary solution may be to use a headset or speakerphone mode so as not to bring the phone to your face. You can also try to gently (without fanaticism) press on the top of the screen to restore the contact of the cable, if the problem is the contact is loose.
☑️ Diagnostics before going to the service
⚠️ Attention: If the phone has recently been dropped or come into contact with water, self-disassembly may permanently damage the device and void your warranty. In such cases, it is better to trust the professionals.
FAQ: Frequently Asked Questions
Why does the screen go blank even when I don’t hold the phone to my ear?
Most likely, the sensor is dirty or covered with a protective film. It is also possible that the sensitivity in the settings is too high, and the sensor reacts to the hand holding the phone, or to glare of light.
Can an Android update fix this problem?
Yes, manufacturers often release patches that correct the operation of sensor drivers. Check the About Phone section for updates. However, it also happens the other way around: new software can introduce bugs.
Does “Pocket Mode” affect this?
Yes, this mode uses the same proximity sensor. If it doesn't work properly, the phone may think it's in your pocket and lock the screen. Try disabling this function in the lock settings.
What to do if, after replacing the screen, the sensor stops working?
When replacing the display, people often forget to re-glue the rubber seal or install the sensor cable correctly. You may also need to recalibrate through the engineering menu, since the new screen may have different light transmittance characteristics.