The situation when a phone call accidentally presses the volume button, turns on the speaker or a call reset is familiar to many smartphone owners. Especially often this problem occurs on Xiaomi and Redmi devices, where the software shell MIUI or HyperOS has its own features of working with sensors. The screen should go out when you bring the phone to your ear, and light up when you move away, but sometimes this mechanism fails, causing serious discomfort.
In this article, we will discuss in detail how to properly configure the lock screen, why it may not work and what methods are available to force the display to turn off during a conversation. Understanding the principles of the proximity sensor will help you avoid accidental pressing and save battery power. We will look at both standard system settings and specialized applications for this task.
Often users confuse automatic screen suppression with manual locking, but in the context of calls, it is the system's response to the user's physical actions and sensor readings. If your phone is not locked itself, this may indicate the need for calibration or the presence of a software conflict. Let's figure out how to bring the device back to normal.
The principle of the proximity sensor on Xiaomi
The main element responsible for locking the screen during a conversation is the proximity sensor. On Xiaomi smartphones, this sensor is usually located at the top of the display, often hidden under the bezel or in the speaker notch, its task is to record the distance to the object (in this case, your ear or cheek) and transmit the corresponding signal to the operating system.
When you bring the phone to your face, the sensor detects a change in light or a reflection of infrared radiation. The system receives a command Proximity Sensor: Near and instantly turns off the display matrix, blocking the touchscreen. This prevents accidental cheek-to-cheek touching of dial icons or call menus. As the device moves away, the screen should light up again.
However, the sensor can be disrupted by a variety of factors: Pollution, thick-framed protective glass, or software failures in MIUI drivers can lead to false positives or, conversely, to ignore the proximity sensor, in which case the screen remains active and locking does not occur.
- 📱 The sensor can be virtual (software) or physical (hardware), which affects the accuracy of its operation.
- 🛡️ Thick protective glass often covers the sensor area, requiring special calibration of the system.
- ⚙️ In the developer settings, sensitivity parameters that affect the trigger threshold are sometimes available.
⚠️ Warning: If the top of the screen is heavily contaminated or taped with opaque film, the sensor may constantly think the phone is near the ear and the screen will go out on its own without even ringing.
Standard lock settings in the Phone application
The first step to fix the problem is to check the basic settings of the Phone app, which is handled by a system application in the MIUI and HyperOS shell, which may have its own screen management priorities, and users often accidentally turn off the lock function in an attempt to solve other calls problems.
To check your settings, open the Phone app and click on the three dots or gear icon in the corner of the screen. Select Settings or Additional Settings. You'll need to find a section that relates to incoming calls or the general interface. Look for an option like "Block during a conversation" or "Approximation Sensor."
If the switch is activated but the screen is still on, try turning it off and on again.This action will restart the corresponding service in the background. Also worth paying attention to the version of the Phone app - in some cases, an update or, conversely, a rollback to the previous version through Google Play Market or GetApps solves the problem of incorrect operation.
☑️ Checking the call settings
It is important to note that on different firmware versions (Global, China, EEA), item names may differ, and in some cases the option may be hidden in the deep menu "Advanced Call Settings." If you don't find the right switch, your version of the software may control this setting differently.
Calibration of the proximity sensor through the engineering menu
If standard settings don't work, the most effective method is to calibrate the sensor through Xiaomi's engineering menu, which allows you to test hardware components and reset them to factory values, especially after replacing the display or installing a new protective glass.
To enter the diagnostic menu, open the Phone app and type a special code. Most of the time, the combination ##6484## works. Once you enter the code, the CIT menu will open.
Inside the test, you'll see distance values. Close the top of the screen with your hand and remove it. The values should change from 5.0 (or 1.0, depending on the model) to 0.0. If there's no reaction, press Calibrate or Calibrate. Follow the instructions on the screen: usually close the sensor with your hand, then remove it, then press OK or Pass.
| Parameter | Normal value. | Failure value | Action. |
|---|---|---|---|
| Distance (Distance) | 0.0 - 5.0 cm | Constant 0.0 or 5.0 | Sizing |
| Status (Status) | Near / Far | Only Far. | Cleanliness check |
| Raw Data | Changes. | It doesn't change. | Reboot. |
⚠️ Note: Do not change other options in the engineering menu CIT, If you are not sure about their purpose, incorrect settings can lead to incorrect operation of other functions of the phone.
What if the code doesn't work?
Using third-party applications to control the screen
When Xiaomi's system tools fail, Google Play apps come to the rescue, which intercept screen control during a call, and they run on top of the standard interface and force the display to be extinguished by a timer or when a conversation begins.
One popular solution is the Screen Off During Call app, or its analogues, and once you install the apps, you have to give them special permissions, first of all, access to telephony and, critically, permission to Drraw over other apps, without which the app won't be able to block the call interface.
In the settings of such software, you can often choose to work: block immediately at the beginning of the call or only when you lift it to the ear (using a software sensor), and some programs allow you to adjust sensitivity to avoid false positives in the pocket.
- 📲 Require permanent permits to work in the background.
- 🔋 It may slightly increase battery consumption due to constant monitoring.
- ⚙️ Often require disabling battery optimization for the locker app itself.
It’s worth remembering that using third-party software is a trade-off, and it can conflict with Android system security updates. If the app stops working after the OS update, check its compatibility or try an alternative.
The effect of protective accessories on the operation of the sensor
One of the most common but common reasons for a screen lock failure is security accessories. Cheap or misfitted security glasses can have an opaque frame that covers the proximity sensor area. Visually, this may be invisible, but for an infrared beam it is an insurmountable barrier.
If you recently put on a new glass and the problem came after that, the reason is almost certainly the accessory. The sensor on Redmi and Xiaomi is often located very close to the edge or in the narrow space between the speaker and the body. Even a millimeter shift of glass can disrupt the work.
In some cases, software compensation through the calibration menu described above helps, but the physical overlap of the sensor is difficult to fix. The best solution is to replace the protective glass with a model with a cutout under the sensor or with a transparent zone at the top.
⚠️ Warning: When buying a security glass for Xiaomi, always check with the seller whether it is compatible with your model, especially with regard to cutouts for sensors and speakers.
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Try temporarily removing the security glass and checking the call, and if the problem is gone, look for glass with smaller margins or a transparent top.
Additional methods and resetting settings
If neither calibration nor applications have worked, more radical methods are worth considering, sometimes the problem is accumulated software debris or a conflict of system caches, in which case resetting the phone application settings to factory values can help.
To do this, go to Settings → Apps → All Apps → Phone. Select “Clean” and then “All Data.” This will not delete your contacts or call history (as they are stored in a separate storage or acc), but reset the interface settings and logic of the call.
As a last resort, if the problem occurs after the system update, you can try to turn off the automatic brightness, since the light sensor is often paired with the approximation sensor. Also check if the In-pocket mode is enabled in the locking settings, which may behave incorrectly on some versions of the software.
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Comprehensive screen check: Screen cleanliness, CIT calibration and lack of conflicting accessories solve 95% of locking problems.