Modern smartphones Xiaomi POCO line are equipped with many features designed to simplify interaction with the device, but one of the most common problems users become spontaneously pressing buttons during a phone conversation. Locking the screen when you bring the device to the ear is a basic feature that should work automatically thanks to the proximity sensor, but in the shell of MIUI or HyperOS settings can behave differently than expected. If your screen continues to burn or go out too early, it is not only annoying, but can lead to the accidental termination of the call or send incorrect messages.
Most of the time, the problem isn't with hardware breakdown, but with software conflicts or downed sensor calibration. The POCO sensor is located at the top of the display, often hidden under glass, making it sensitive to protective films and contamination. Understanding how the system handles this process will help you quickly fix the malfunction and regain comfort when communicating.
In this article, we will take a detailed look at how to set up automatic locking, where to find hidden engineering menus to check sensors, and what to do if standard methods don’t work. You will learn how to distinguish a software failure from a physical malfunction, and which applications can interfere with the operation of a standard call.
The principle of the approach sensor at POCO
The fundamental element responsible for quenching the screen during a conversation is the proximity sensor.On Xiaomi smartphones POCO You use either an optical or an ultrasonic sensor that measures the distance between the surface of the screen and the object (your ear), and when you hold the phone, the sensor picks up the reflected signal and sends the system a command. ACTION_PROXIMITY_NEAR, which leads to the switching off of the touchscreen and display to save energy and prevent false presses.
However, this mechanism can be disrupted by software errors in the MIUI shell. It often happens that third-party applications such as messengers or call "improvers" intercept the control of the sensor. In such cases, the screen may not go out at all or, conversely, go out in your pocket when the phone is not put to anything. It is important to understand that calibration is a process that the system performs automatically when booting, but sometimes requires manual intervention through the engineering menu.
⚠️ Attention: Using aggressive memory cleaners or ads blocking apps may cause the system process responsible for monitoring sensors to stop, making the screen lock feature idle.
It is also worth noting that on some POCO models with a notch screen, the sensor is located directly in the notch area. If you use a solid protective film or a low-quality glass with a black frame covering this area, the sensor may “think” that the phone is constantly in the ear, and the screen will go out immediately after the call starts, preventing you from dialing a number.
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Try temporarily removing the protective glass or film if the screen goes out immediately after the call begins, even before the phone is brought to your ear - this will help diagnose a problem with feelings.
The main settings of the system for locking the screen
The first step in solving the problem should be to check the basic settings of the system, as sometimes the lock function can be accidentally disabled or changed after updating the firmware. In Xiaomi POCO smartphones, the management of this option is often hidden in the depths of the application menu or in special interface settings. You need to make sure that the system call has all the necessary permissions to work with the sensors.
To access key parameters, go to the Settings menu → Annexes → All applications. Search the "Phone" app (or "Mi Dialer" if you use a third-party call) and you're interested in "Permissions" and "Other Permissions" here. This is where the switch is hidden, which is responsible for displaying on top of other applications and working in the background, which is critical for locking the screen.
In addition, some versions of the MIUI shell have a separate setting in the call menu. Click on the gear icon in the Phone app and carefully examine the list of options. Look for "Discourse Sensor" or "Conversation Lock." If this is active but not working, try resetting the app to factory settings to eliminate software glitch configuration.
- 📱 Check if the "approximation sensor" switch is enabled in the settings of the "Phone" application".
- 🔒 Make sure the app has permission to “Display over other windows".
- 🔄 Reset the settings of the Phone application through the About menu if the problem has recently appeared.
- 🛡️ Turn off Pocket mode in the screen lock settings if it conflicts with the sensor.
If you have checked all the settings, the screen still doesn't lock, you may have a deeper layer of the system, so you should check if the screen sensitivity mode is on, which sometimes ignores the commands to disable the touchscreen from the proximity sensor, and make sure that the phone doesn't have themes that modify the system files of the call interface.
Checking and calibrating sensors through the engineering menu
The most effective way to diagnose and fix sensor problems is through the CIT (Customer Integration Test) built-in menu, which allows you to check the performance of each sensor separately and perform manual calibration if the automatic one fails, accessed through a special code in the dialing application.
To enter the diagnostic menu, dial ##6484## or ##4636##. From the list that opens, select Proximity Sensor. You will see a window with two values: the current reading and the threshold. Hold your hand to the top of the screen, the value should change from 5.0 to 0.0 (or vice versa, depending on the software version). If the values do not change, the sensor is either contaminated or physically defective.
If the sensor is responding, but the screen is not locking in time, you need to calibrate. The sensor test menu often has a "Calibration" button. Press it and follow the instructions on the screen: usually you need to close the sensor with your hand, then remove your hand. The system will write down new thresholds. After successful calibration, be sure to restart the device so that the new parameters apply to the power management system.
⚠️ Warning: Do not change the thresholds manually unless you are sure of your actions.Incorrect calibration can cause the screen to go out in your pocket or not respond to an ear-mounted approach.
In some cases, especially after flashing or global updates, calibration data may be lost. The engineering menu allows you to restore it to factory standards. If the test shows that the sensor is not working at all (values do not change even when closed), try to clear the vendor partition cache or perform a full reset, but only after backing up the data.
☑️ Sensor diagnostics
Influence of accessories and protective glasses
One of the most common reasons for the screen locking on Xiaomi POCO is not working properly is physical obstacles. Modern smartphones design involves placing the proximity sensor in a very narrow area, often millimeters from the speaker. Any thickening in this area, whether it is a thick protective glass, a case with high sides or even a layer of glue, can distort the sensor readings.
Black-framed protective glass (2.5D or 3D) often overlaps the invisible area of the sensor. Even if the hole appears to match, a half-millimeter offset is enough to block the operation. In such cases, the screen can behave chaoticly, either fade permanently or not respond to the application. The solution is to replace the accessory with a model with a cutout under the sensor or remove the protection for inspection.
Also worth noting is the cases. Some cases, especially the shockproof ones, have protruding edges that may partially overlap the top of the screen. If you notice that the problem occurred after you bought a new case, remove it and check the call. In addition, the accumulation of dirt, fat or dust in the upper speaker area can "clog" the sensor, requiring careful cleaning with a soft cloth.
| Type of obstacle | Probability of problem | Symptoms. | Decision |
|---|---|---|---|
| Frameless protective glass | Tall. | The screen goes out immediately. | Replace the glass |
| Dirty sensor | Medium | Unstable work | Drink it with alcohol. |
| Tight case | Medium | The screen's not going out. | Remove the case |
| Low quality film | Low. | Delayed reaction | Take the film off. |
If you carry your phone in your pocket with your keys or small change, microparticles can clog the speaker grille behind which the sensor is hidden, and regular preventive cleaning of the top of the case will help avoid such situations.
How to clean the sensor correctly?
Solving problems with third-party applications
Often users install alternative applications for calls from the Google Play Store, such as Truecaller, Dialer or various number detectors. These applications are embedded deeper than it seems, and can intercept the control of the proximity sensor. If a standard Xiaomi call has been replaced or disabled, the system may not properly process the signals about the lock screen.
Conflicts can also arise with gesture control applications, such as handheld gesture control programs or smart screen blockers, which can interfere with the system mechanism. To identify the culprit, try running the phone in Safe Mode. To do this, press the turn off button and then (hold) on the "Stop" button on the screen until you are prompted to go to Safe Mode.
If the problem is gone in safe mode, it's definitely third-party software. Start removing newly installed applications related to calls, contacts, or system optimization. Pay special attention to applications that require permission to access the call log and phone. After removing the problem application, restart the device in normal mode and check the sensor.
- 📞 Remove third-party number detectors if they cause crashes.
- 🚫 Check the list of applications with sensor access in the "Privacy" section".
- 🔍 Use Safe Mode to Find Conflicting Software.
- ⚙️ Reset the "Special Features" settings if there are active scripts there.
Also worth mentioning is the Smart Response feature, or voice control, which can keep the screen active while waiting for a command. Turn it off in the Google Assistant or Mi Assistant settings if you don't use them. Sometimes it's the wait for a voice command that prevents the screen from going out when you hold the phone to your ear.
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Third-party caller apps often don’t have full MIUI optimization, which is the main reason for proximity sensor failures.
Alternative methods and resetting settings
If none of the above methods work, then more radical measures are needed: the first step can be to reset all the phone settings to factory settings, which will delete all your data, photos and applications, so backup is a must.
To perform the reset, go to Settings → About Phone → Settings Reset → Erase all data. Once back to factory, take your time to install all applications at once. First, check the call on a clean system. If the problem is solved, install the apps one by one to identify the culprit.
In extreme cases, even if the flashing doesn't work, it can be a hardware malfunction. On some POCO models, the proximity sensor plume can move away or oxidize. In this situation, only contacting an authorized service center to replace the module or plume will help. Self-repair without experience is not recommended, since you can damage the display plume.
⚠️ Warning: Before resetting your settings, make sure you remember the password from your Mi Account.Otherwise, after resetting, the phone may lock due to activated theft protection.
Sometimes it helps to update your firmware to the latest available version. Xiaomi developers regularly release patches that fix hardware bugs. Check for updates in the System Update menu. If you have a beta version of your firmware, consider rolling back to a stable version, since bugs are more common in beta versions.