When making a call, the screen on Android goes blank and does not turn on: what to do

Immediately after dialing a number or when an incoming call, the Android smartphone screen goes blank and ignores any touches, which makes it impossible to control the call due to a malfunction of the proximity sensor, which is false records the location of the device near the ear.

There can be many reasons for this behavior: from banal contamination of the protective glass at the top of the display to serious hardware malfunctions after a fall or moisture. In some cases, the culprit is a software conflict or poor-quality protective glass glued in violation of technology. Understanding how the sensor works is the first step to successfully solving the problem without contacting a service center.

In this article we will analyze in detail all the possible reasons why The display does not turn on during a conversation, and provide step-by-step guide for diagnosing and troubleshooting problems. We will look at both software configuration methods and physical methods for checking the health of the equipment so that you can return your gadget to full functionality.

The principle of operation of the proximity sensor and the reasons for the failure

To understand why the screen does not light up, you need to understand the physics of the process. At the top of the smartphone, usually next to the earpiece, there is an infrared proximity sensor. It consists of an emitter and a receiver: the first sends out an invisible beam, and the second reads its reflection. When you bring the phone to your ear, the beam is reflected from your head, and the system receives a signal to turn off the display to save energy and prevent accidental clicks with your cheek.

If proximity sensor is dirty, blocked or software glitched, it can constantly send a signal that an object is nearby. As a result, the system locks the screen immediately after dialing or answering a call. This is a classic situation when the software performs its function properly, but receives incorrect data from the hardware.

Often the problem is aggravated by the use of thick cases or incorrectly glued protective glasses. If the accessory blocks the sensor area, the beam cannot go out or return, which is interpreted by the system as the constant presence of an object in the immediate vicinity. In such cases, even high-quality calibration may not give the desired result without physically removing the obstacle.

⚠️ Attention: Do not try to check the operation of the sensor by pointing powerful light sources or lasers at it - this can lead to irreversible damage to the sensitive photodetector.

Diagnostics through the engineering menu and test applications

First of all, you need to make sure that the problem really lies in the sensor, and not in the system freezing of the touchscreen. For this purpose, Android provides hidden engineering menus, which can be accessed through a special code. Enter ##6484## or ##4636## in your phone (combinations may differ depending on the manufacturer, for example, for Xiaomi or Samsung). In the menu that opens, find the item "Proximity Sensor" or "Proximity sensor".

In testing mode you will see the current sensor value. It is usually displayed as "Near" or "Far" or as a number. Cover the top of the screen with your hand and the value should change. If there is no response or the value constantly shows “Near” even when the screen is open, this confirms a hardware or software lock.

An alternative option is to install third-party utilities from the store Google Play, such as "Phone Tester" or "Sensor Test". These applications provide a more visual interface for checking all of the built-in sensors. They allow you to track the slightest fluctuations in readings that may not be noticeable in the standard engineering menu.

If tests show that the sensor does not respond to hand movements at all, most likely the cable inside the case has come loose or the module itself has failed. If it responds, but is too sensitive or “sticks,” the problem can be solved by software calibration, which will be discussed later.

Software calibration of the proximity sensor

Many modern smartphones allow you to reset the sensor settings directly through the system menu or special applications. This action causes the system to re-determine the sensor response limits. For devices with blank Android or shells of type MIUI the installation of the "Proximity Sensor Reset/Fix" utility is often required.

The calibration process usually looks like this: you place the phone on a flat surface, launch the application and press the "Calibrate" button. At this point, the system reads the reference values ​​of the "far" position. You may then be asked to cover the sensor with your hand to record the "close" position value. After completing the procedure, you need to restart the device.

What to do if the application does not see the sensor?

If the calibration utility gives an error or does not detect the sensor, try granting it advanced permissions in the application settings. Sometimes enabling developer mode and selecting a specific USB or debugging configuration helps, but this rarely affects the internal sensors. In 90% of cases, lack of response means a physical malfunction.

It is worth noting that on some models, especially from Chinese manufacturers, the calibration function is built directly into the Recovery Mode or into the advanced display settings. Look for items like "Calibration" in the "Hardware" or "Sensors" sections. You should not neglect this step, as it is safe and often eliminates logical errors accumulated during operation.

The influence of accessories and physical pollution

One of the most commonplace, but common reasons why the screen does not turn on during a conversation is a physical obstacle. Dust, finger grease or adhesive residue from previous glass can create a film that is impenetrable to infrared radiation. Thoroughly wipe the top of the display with microfiber moistened with a special screen cleaner.

Particular attention should be paid to the protective glass. Cheap alternatives often have a black frame around the perimeter, which may be wider than the original screen and block the sensor area. Even if the glass is visually glued smoothly, its thick coating in the sensor area can distort the signal. Try temporarily removing the protection and checking the operation of the phone in its “naked” form.

Also check the case. Some bumper models have protruding sides or a solid front panel that covers the upper end of the smartphone. Make sure there are proper cutouts in the speaker and sensor areas. If the case fits tightly to the glass at the top, it can create the effect of constant proximity.

Failures in the operating system and applications

Sometimes the problem is software in nature and is associated with a conflict in system processes or third-party software. For example, call recording applications, caller ID, or launchers can intercept control of the sensor and not give it back to the system. In such cases the screen goes blankbut does not turn on because the background process is holding the lock.

To identify the culprit, try booting the phone into safe mode. In this mode, only system applications are launched. If the problem disappears in Safe Mode, then the problem is in one of the applications you installed. Start uninstalling recently installed apps related to telephony or screen control one by one.

It is also worth checking for updates for the operating system. Developers often release patches to fix bugs in sensor drivers. Go to Settings → About phone → System update and check the availability of new software versions. Sometimes resetting the network settings or completely resetting the phone settings (with preliminary saving of data) helps.

Problem type	Probable cause	Solution method	Difficulty
The screen does not turn on	Dirt on the sensor	Cleaning the top of the screen	Low
Permanent shutdown	Protective glass	Removing or replacing glass	Low
Failure after update	Software error	Resetting or flashing	Average
No reaction to hand	Cable loss	Disassembling and connecting the cable	High
Chaotic behavior	Application conflict	Safe mode and software removal	Medium

Hardware faults and the need for repair

If all software methods have been exhausted, and cleaning did not help, most likely there is a hardware failure. The proximity sensor is a separate component that can fail due to shock, moisture, or normal wear and tear. In modern smartphones, it is often integrated into the front camera cable or into a separate module at the bottom of the screen (in models with under-screen sensors).

If moisture gets inside the case, the sensor contacts can oxidize, which leads to a short circuit or a constant response signal. Visually, this can be noticed by a change in color in the speaker area or the appearance of condensation under the glass. In this case, independent repair without special equipment is impossible and even dangerous.

Also a common problem is the cable connector coming away from the motherboard. This often happens after falls, even if there is no external damage to the case. Internal vibration or shock can dislodge the connector by a fraction of a millimeter, enough to cause loss of contact. The device must be disassembled and the cable reconnected.

⚠️ Attention: If the phone has been dropped into water, do not under any circumstances try to dry it with a hairdryer or on a battery. High temperatures can melt the adhesive holding the display in place and damage the sensors. Take the device to a service center for professional cleaning in an ultrasonic bath.

Temporary solutions and workarounds

Before you have time to fix cause globally, you can use temporary measures to make calls comfortably. Some Android skins allow you to disable the proximity sensor programmatically, although this feature is often hidden. Try entering the code ##7780## (does not work on all models) or find the "Disable proximity sensor" item in the call settings.

Another way is to use a headset. When connecting wired headphones or a Bluetooth headset, the system automatically switches the audio stream and often ignores the proximity sensor, leaving the screen on. This allows you to control a call through the phone interface, even if the built-in sensor is faulty.

You can also try disabling the "Prevent accidental press" feature in the display settings. Sometimes this feature, when paired with a sensor, causes unnecessary blocking. Go to Settings → Display → Preventing accidental clicks and deactivate the switch.

Is it possible to completely disable the sensor forever?

Complete software disabling of the sensor is only possible on rooted devices with superuser rights through editing system build.prop files or using special Magisk modules. For regular users, this is risky as it can cause the screen to go blank in my pocket, draining the battery.

Frequently Asked Questions (FAQ)

Why does the screen go blank even when I don't hold the phone to my ear?

This means the proximity sensor sends a false signal that an object is nearby. Most often, the reason is contamination of the sensor, incorrect calibration, or a software glitch that “remembers” the locking state.

Can viruses affect the operation of the sensor?

The direct influence of viruses on sensor drivers is extremely rare. However, malware can overload the processor or create conflicts in system processes, which indirectly leads to incorrect operation of all sensors, including the proximity sensor.

Will resetting to factory settings help?

Resetting to factory settings (Hard Reset) eliminates all software errors and application conflicts. If the problem is caused by a glitch in the OS, this will help. If the sensor is physically broken or dirty, resetting will not give any result.

Why did the sensor stop working after replacing the screen?

When replacing the display, non-original low-quality components are often used, in which the proximity sensor is either missing or connected incorrectly. Also, the technician might have forgotten to connect the sensor cable or damaged it during installation.

How to check the sensor without the engineering menu?

The easiest way is to make a test call to another number and raise your hand to the top of the screen. If the screen goes blank and does not turn on after you remove your hand, it means the sensor is “stuck” in the closed state. For more accurate diagnostics, use applications like Phone Tester from the Play Market.