A black screen during an incoming call on Android, when you hear beeps, but do not see the caller's name and cannot answer, most often indicates a malfunction of the proximity sensor, which mistakenly blocks the display, mistaking the phone for being pressed to your ear.
Reasons: which proximity sensor stops correctly transmitting a signal to the system can be many: from banal dirt on the protective glass to deep software glitches in the firmware. In some cases, the problem lies in physical damage to the cable or the sensor itself after the device was dropped. Understanding the mechanism of operation of this component helps to quickly localize the malfunction and choose the correct method of restoring functionality.
In this article we will analyze in detail diagnostic algorithms, software calibration methods and hardware repair methods. You'll learn how to check hidden engineering menus, what settings in the system can block the screen, and when it's time to take your phone to a service center. Ignoring this problem may lead to you accidentally pressing the volume buttons or ending calls with your cheek, so resolving the issue requires promptness.
The principle of operation of the proximity sensor and its effect on the screen
The main culprit for dimming the display is infrared proximity sensor, usually located at the top of the front panel of the smartphone next to the speaker. Its task is extremely simple: it emits a beam invisible to the eye and reads the reflected signal. When you bring the phone to your ear, the beam is reflected from your head, the sensor detects the change in distance and sends the system a command to turn off the backlight and touchscreen.
If this mechanism fails, the screen may go out before you bring the phone up, or, conversely, not turn on when you have already moved the device away from your face. Modern models Samsung, Xiaomi and Pixel use different technologies for implementing this sensor: from classic infrared diodes to ultrasonic and virtual sensors based on machine learning algorithms and accelerometer data.
Often, users are faced with the fact that after replacing the protective glass or installing a low-quality film, the sensor begins to work incorrect. The thickness of the material or the adhesive layer can distort the signal, creating the illusion that an object is constantly present near the phone. In this case, the system “thinks” that the phone is still at your ear and blocks the display from turning on when there is an incoming call.
⚠️ Attention: If you have recently changed the display module or protective glass, the problem in 80% of cases is associated with incorrect installation or a defective accessory that overlaps the sensor area.
It is also worth considering that in budget smartphone segments, software processing of the sensor signal may be less accurate. This leads to false alarms, especially in bright sunlight, when external radiation “clogs” the signal from the phone’s own infrared diode.
Try wiping the top of the screen with an alcohol wipe. Sometimes a greasy film from fingers or dust interferes with the operation of the infrared sensor.
Software settings and Android system failures
Before suspecting a hardware failure, it is necessary to rule out software conflicts. Often after updating the operating system Android or installation of third-party applications for managing calls, the sensor settings may be lost. First of all, you should check whether the Do Not Disturb mode or specific energy saving profiles are activated, which aggressively control the operation of the peripherals.
In some shells, such as MIUI or OneUI, there are separate menu items that are responsible for the behavior of the screen during a call. For example, the "Prevent accidental clicks" feature may be too aggressive. It is also worth paying attention to call blocking applications or caller ID, which intercept control of the lock screen and may conflict with the standard dialer interface.
- 📱 Check the settings in the section
Settings → Accessibility → Uninstall call(or a similar path for your model). - 🔄 Clear the cache of the "Phone" and "Contacts" applications through the app management menu.
- 🛡️ Disable all third-party themes and launchers that can modify the lock screen.
If the problem appeared after installing a specific software update, perhaps in a new version There is a bug in the firmware. In such cases, a temporary rollback to factory settings or waiting for a patch from the manufacturer helps. However, before completely resetting your data, make sure that you have a backup copy of important information.
Diagnostics through the engineering menu and special codes
To accurately check the health of the sensor, you can use the hidden engineering menu, available on most devices running Android. This method allows you to see raw data from the sensor in real time, which makes it possible to understand whether the phone sees an obstacle in front of the screen. Entering special codes in the dialer provides access to equipment tests.
The most universal code is ##7780## or #0# (for Samsung), which launches the testing menu. You need to find the section Proximity Sensor. In this mode, the screen will display numeric values or status indicators (such as "Near" or "Far"). Place your palm on the top of the phone and remove it: the values should change instantly.
| Smartphone brand | Code to enter the test | Menu section | Normal reaction |
|---|---|---|---|
| Samsung | #0# |
Sensor / Proximity | Value changes with 5.0 to 0.0 |
| Xiaomi / Redmi | ##6484## |
Proximity Sensor | The indicator is on/off |
| Huawei / Honor | ##2846579## |
(Sensor Test) | Changing the Near/Far status |
| Pixel / Stock Android | ##4636## |
Testing / Sensor | Value change graph |
If the test values do not change when you raise your hand, this is a direct sign of a hardware malfunction or a critical driver failure. If the test is successful, but the screen goes blank in normal call mode, the problem lies in a software conflict in applications or system settings.
What to do if the codes do not work?
On some modern models (especially American versions), access to the engineering menu via USSD codes may be blocked by the telecom operator or manufacturer. In this case, download an application like "Phone Tester" or "AIDA64" from Google Play - they show sensor data without entering codes.
Physical obstacles and the influence of accessories
One of the most common reasons why the screen does not light upis external physical factors. Users often do not notice that the case, especially the “book” type model with a magnetic clasp or a thick side, can block the sensor’s operating area. Even a millimeter displacement of the protective glass relative to factory tolerances can cause permanent blocking of the screen.
Check the top frame of your smartphone. If you are using thick tempered glass, try carefully removing it and checking the ringer's operation. The adhesive base of cheap glasses can become cloudy or shift over time, creating an optical barrier to infrared radiation. It is also worth inspecting the speaker area for moisture or condensation that refracts the sensor rays.
⚠️ Attention: Do not use magnetic holders in a car that are attached to the top of the screen. The magnetic field can disrupt the operation of not only the compass, but also the proximity sensors on some phone models.
Sometimes the problem is solved by simple cleaning. Dirt, facial oils, or cosmetics may accumulate in the micro-cracks around the sensor. Use a soft cloth lightly dampened with isopropyl alcohol to gently clean this area without pouring liquid inside the case.
☑️ Checking for physical causes
Calibrating the proximity sensor without root access
If the sensor is physically functional, but does not work correctly, it may require software calibration. This procedure causes the system to redefine the boundaries of "near" and "far". On many smartphones, this can be done through the standard engineering menu, which we discussed above, by selecting Calibration.
The process usually looks like this: you place the phone on a flat surface, press the calibration button and wait a few seconds while the system counts zero values. You may then be asked to cover the sensor with your hand. After successful completion, the phone will reboot and the sensor settings will be reset to factory settings.
For devices where the standard menu does not offer such a function, there are special applications from the store Google Play, for example, "Proximity Sensor Reset/Fix". They emulate the calibration process by writing new threshold values to a system file. However, the effectiveness of such utilities depends on the access rights that the application has on a specific phone model.
Calibration only helps if the sensor itself is physically intact. If the sensor is broken or detached from the board, software methods are powerless.
It is important to perform calibration in stable lighting conditions and without unnecessary objects near the phone. After the procedure, be sure to test the operation with an incoming call by making a test call to your number from another device.
Hardware repair and replacement of components
When all software methods have been exhausted, and calibration does not produce results, we are talking about a physical breakdown. In modern smartphones, the proximity sensor is often integrated directly into the display cable or into a separate front camera module. This complicates repairs, since replacing only the sensor may require micro-welding or replacing the entire assembly.
In service centers, diagnostics begin with testing the sensor contacts with a multimeter. If the circuit is open or shows a short circuit, the part needs to be replaced. The cost of such repairs varies depending on the model: on budget phones they often replace the entire top cable, and on flagships they may try to resolder a separate component.
Independent repair is not recommended if you do not have experience working with small electronics. Careless opening of the case can damage fragile cables or break the seal of the device, which will lead to moisture getting inside in the future. In addition, non-original spare parts often have low quality sensors, and the problem may return after a month.
Is it possible to disable the proximity sensor forever?
Technically, this is possible through special applications or modified firmware, but doing this is highly not recommended. Without the sensor, you'll be constantly tapping the screen with your ear during a call, putting a call on hold, putting it on speakerphone, or dropping a call. This will make using the phone during talk time extremely inconvenient.
Why does the screen go blank even when I'm not holding the phone to my ear?
This is a sign of the sensor being “stuck” in the “close” position. The cause could be a software glitch, dirt on the sensor, or physical damage that causes it to constantly send a signal about the presence of an obstacle. Try rebooting or cleaning the top frame.
Does the brightness of the screen affect the operation of the sensor?
There is no direct effect, but at maximum brightness in the dark, some cheap sensors may work less stably due to stray light from the display itself, if the housing design is not ideal. This is usually solved by updating the software.
What to do if the problem appeared after a fall?
Most likely, the sensor cable came off due to the impact or the sensor itself was cracked. In this case, software methods will not help. You need to open the device and check the connection of the cable, and if necessary, replace the part.
Will a reset to factory settings help?
A hard reset deletes all user data and application settings, which can eliminate a software conflict. This is worth trying before going to the service, but be sure to back up your contacts and photos before doing this.