The situation when the screen goes out during a conversation on a Xiaomi smartphone is one of the most common and annoying problems for MIUI users. Instead of seeing the interlocutor number or call control buttons, the owner of the device is faced with a black display, which does not respond to any touch.
Most often, the root of the evil lies in the incorrect operation of the Proximity Sensor, which is designed to save battery power and prevent accidental cheekstrokes by turning off the backlight of the display when the phone is brought to the ear. However, if the calibration mechanism is knocked down and the software misinterprets the sensor data, the screen may go out long before you bring the device to your face, or not turn on at all.
In this article, we will look at all the possible causes of a call to go out and offer proven solutions, including software failures in the HyperOS or MIUI shell, as well as physical interference that users often ignore. Understanding the nature of a fault is the first step to successfully fix it without visiting a service center.
How the proximity sensor works in Xiaomi smartphones
To effectively combat this problem, you need to understand how the equipment works: Xiaomi’s current smartphones use an optical or ultrasonic proximity sensor, which emits an invisible beam and analyzes the reflected signal. If the distance to the object (your ear) is less than a certain threshold (usually the distance to the object) 2-3 cm, the system receives command PROXIMITY_NEAR and locks the display.
In budget models and devices with a neck ("bang") in the screen, the sensor is often located at the top of the case. In more advanced models, where aesthetics without a bezel are important, the technology of an ultrasonic sensor embedded under the display is used, and this is where software conflicts often arise, leading to the screen going out for no apparent reason.
The sensor data processing algorithm can fail if the background processes overload the processor or if the device driver is not working properly after the update, in which case the screen goes out even when the phone is on the table. It is important to distinguish between a physical sensor failure and a software glitch, since their treatment methods are radically different.
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The proximity sensor is a screen watchman that should only respond to the phone being brought to the ear, not to random movements in the air.
The effect of protective glasses and covers on the operation of the sensor
One of the most common, but often ignored, reasons why the screen goes out when you call is to install the security film or glass incorrectly. Many users, wanting to protect the display, buy cheap accessories that block the area of the sensor. Even a microscopic film above the sensor can distort infrared radiation, making the system think that the phone is near the ear.
This is especially common in models with a front camera embedded in the screen, or with a dynamic cutout. If the security glass has a black bezel or a thick layer of glue at the top, the proximity sensor will be permanently locked, so you take the phone in your hands and the screen is already off, and you can only unlock it with a power button.
Also worth noting are the cases. Some bumper models have too high bumpers that physically overlap the sensor area. If you recently changed the accessory and the screen started to go out spontaneously immediately after that, try removing the case and checking the phone's performance in a "clean" form.
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Use full-glue security glasses or specially designed for your Xiaomi model, which takes into account the location of the sensors.
Checking for physical obstacles is the first thing to do before you start a complex diagnostic software, make sure there is no dust, dirt or glue residue from old glass in the top speaker area, and even a dense layer of dust can cause a false lock system to work.
Software failure and sensor calibration in the engineering menu
If physical obstacles are eliminated, the software calibration is likely to have gone wrong. There is a hidden engineering menu in the MIUI and HyperOS shells that allows you to diagnose and reconfigure the proximity sensor, and this is the most effective way to solve the problem when the screen goes out for no reason. To log into the menu, you need to enter a special code in the Phone application.
Enter ##6484## or ##4636## (code may vary depending on the model and version of Android). In the CIT (Customer Information Test) menu, find "Proximity Sensor" or "Proximation Sensor" and you'll see two values here: current status and threshold.
☑️ Sensor diagnostics
The calibration process is as follows: you cover the top of the screen with your hand (simulating a conversation), the value should change to 5.0 (or Close). When you remove the hand, the value should become 0.0 (or Far). If the values "dance" or do not change, press the Calibrate button. After successful calibration, the system will overwrite the reference values, and the screen will stop fading incorrectly.
| Sensor status | Value (Far) | Meaning (Near) | Action. |
|---|---|---|---|
| Norma. | 0.0 | 5.0 | No calibration required. |
| Calibration failure | 1.0 - 4.0 | 5.0 | Calibration required |
| Permanent lockdown | 5.0 | 5.0 | Check the safety glass. |
| Malfunction | 0.0 | 0.0 | Hardware breakdown |
Sometimes a single procedure is not enough, and it has to be repeated 2-3 times to achieve a stable result.
What if the code doesn't work?
System settings and energy saving
Aggressive energy saving policies in MIUI often cause background services that are responsible for communication to malfunction. If the screen goes out and does not light up on an incoming call, it may be that the system has forced the process of processing sensor data to sleep, which is typical for devices that work without rebooting for a long time.
It is worth checking the Advanced Settings settings in the call section. Some firmware versions have a "Draw-up Sensor" option that can be forced to turn on or off, however, turning off the sensor completely is a temporary solution, since during a conversation the screen will respond to the touch of the cheek, which can lead to the accidental termination of the call or turn on the speakerphone.
Also, look for Do Not Disturb or Sleep mode. If the phone is in your pocket or bag, smart algorithms can mistakenly lock the screen, believing (the environment) to be dark and closed. Check if the In-Pack mode is activated, which uses the same sensor to prevent random action.
Resetting network settings and calls can help if the problem is a system file conflict. Go to Settings → Apps → All Apps → Phone and select Clear -> Clear Everything. This won't delete your contacts, but will return the call settings to factory settings, which often solves the fading screen problem.
Conflicts of third-party applications and updates
Installing third-party calling apps (e.g., Truecaller, Viber, WhatsApp with phone rights) can create conflicts with the system’s “caller.” If you have multiple apps that have access to the microphone and sensors, the system may not know which one to give priority to screen control, resulting in a chaotic display going out.
Especially often problems arise after a firmware update. Xiaomi developers can change the algorithms of the sensors in the new version of MIUI or HyperOS, which leads to bugs on devices that are already “accustomed” to the old settings. If the problem appears immediately after the update, you should wait for a patch or try to roll back the system.
Check which apps have sensor permissions. Go to Settings → Privacy Protection → Permissions Management → Approximation Sensor. Make sure that only the Phone system app and the messengers you need are available.
⚠️ Warning: Installing “modified” versions of phone apps from unverified sources can result in a full call feature failure and a permanent black screen.
Hardware malfunctions and repairs
If neither calibration nor resetting has helped, and the screen continues to go out at inappropriate times, there is a high probability of hardware failure. The proximity sensor is a physical component that can fail due to a fall, moisture or just wear and tear, in which cases software methods are powerless.
Often the problem lies in the plume connecting the top board to the motherboard, when the contact falls, the sensor begins to transmit chaotic signals, and the oxidation of the contacts after moisture (even condensate) causes the system to see a permanent obstacle in front of the sensor.
To diagnose hardware, you can use third-party apps from Google Play, such as “Proximity Sensor Reset/Fix” to see the sensor’s schedule in real time. If the graph shows a constant unit (closed) without a physical overlap, you need to change the module.
⚠️ Attention: Opening the case of the smartphone to check the sensor plume on your own can lead to loss of warranty.If the device is warranty, contact an authorized service.
Replacing the proximity sensor is a low-cost and fast procedure, and service centers either change the sensor itself (if it is separate), change the top board (where it is soldered), or change the entire display module assembled if the sensor is built into the screen.