The situation when during a phone conversation the screen of the smartphone does not go out, but continues to burn, is familiar to many users. This is not just distracting from the conversation, but also creates a real risk of making a so-called “pocket dial” or accidentally pressing the reset button. In Xiaomi and Redmi devices, a special module is responsible for this function, which must respond to the phone’s bringing to the ear. However, in the shell of MIUI or HyperOS, the settings of this component can be hidden or work incorrectly due to software failures.
The main thing that controls the shutdown of the display is the proximity sensor, which detects the change in light and distance to the object. If the screen continues to glow when you press the smartphone against your head, then the system does not receive a signal that the device is near the ear, which can be caused by both physical obstacles and software conflicts inside the Android operating system.
Most of the time, the problem is solved by calibrating correctly or changing the parameters in the engineering menu. However, it is worth considering that modern models of flagship smartphones often use ultrasonic sensors embedded under the screen, which work differently than classic infrared modules. Understanding the type of your sensor will help you choose the right method of diagnosis and troubleshooting.
The principle of the sensor approach in smartphones Xiaomi
The locking technology is based on constant monitoring of the space in front of the top of the device. In classic Xiaomi models, an infrared emitter and receiver are used. When you bring the phone to your face, the IR ray is reflected from your cheek and returned to the receiver, which gives the system the command to turn off the touchscreen and extinguish the matrix.
In more expensive models, such as the Xiaomi Mi series or the Xiaomi 13/14 series, manufacturers often abandon the visible hole in favor of hidden solutions. This can use ultrasonic sensing technology or use a front-facing camera with artificial intelligence algorithms to determine the position of an object, which makes the system more reliable, but also more difficult to diagnose when crashes.
If the sensor is working correctly, the screen goes out almost instantly after the device is lifted. Delay or lack of response indicates that the sensitivity threshold is not set correctly or the ProximitySensor software module is frozen. It is important to note that the sensor can also be affected by third-party factors, such as thick protective glass or contamination of the upper edge.
Why can the sensor lie?
Basic configuration through the call menu
The first step in fixing the problem is to check the standard telephony settings. There is a separate item in the MIUI shell that forcibly activates the lock function, often users accidentally turn it off or the system resets the settings after a major update.
To check, you need to open the standard Phone app and go to the call settings, and you need to find the section that handles incoming calls, and that's where the switch that controls the display's response to approach is hidden, and if the slider is turned off, the screen will burn constantly, regardless of the position of the phone.
- 📞 Open the phone application (green handset).
- ⚙️ Click on the gear icon or three dots in the corner to enter Settings.
- 👂 Select Incoming Calls (or “Reception Mode»).
- ✅ Make sure the proximity sensor switch is activated.
Once this option is enabled, it is recommended to restart the device so that the changes take effect. If the switch has already been active, try turning it off, waiting 10 seconds and turning it on again.
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If there is no Approximation Sensor in the call settings, it could mean that your version of MIUI hides this option or uses automatic control without manual intervention.
Engineering menu and precise calibration
When standard methods don't work, you have to go to a deeper setup through the engineering menu, which is a hidden part of the system that's designed to test the hardware, and you can precisely calibrate the sensor by setting new threshold values.
To enter this mode, you use a special combination of characters in the dialer. Enter the code ##6484#. If the code is entered correctly, the CIT (Customer Integration Test) menu will open. In the list of tests, you need to find the Proximity sensor.
☑️ Calibration of the sensor in CIT
In the test mode, you'll see two values. They usually change from 5.0 to 0.0 (or vice versa) when you close the top of the screen with your hand. If the numbers don't change, then the sensor is physically defective or software locked. If they change, but the screen doesn't go out when you call, you need to recalibrate.
⚠️ Note: Do not change the values manually in the input fields unless you understand their purpose. Use only the Calibrate or Pass button to save the current readings as reference values.
Problems with protective films and accessories
One of the most common reasons for the screen locking to work is security accessories. Many users, when buying expensive glass, do not take into account its thickness and transparency for infrared radiation. The film can create optical noise, which the sensor perceives as the constant presence of an object nearby.
This is especially true of cheap, perimeter-black security glasses, and if this frame overlaps the sensor area (usually a narrow strip above the speaker), the system will think that the phone is pressed against the ear all the time, or vice versa, it will not see obstacles, in which case the screen may go out on its own or not go out at all.
To diagnose, you need to carefully remove the protective glass or film and check the operation of the call, if the problem has disappeared, then the accessory is chosen incorrectly, in some cases, cutting a small hole above the sensor helps, but this violates the aesthetics and integrity of the protection.
| Accessory type | Probability of conflict | Recommendation |
|---|---|---|
| The original glass of Xiaomi | Low. | Replace in case of damage |
| Cheap framed glass | Tall. | Remove or cut |
| Hydrogel film | Medium | Check the landing. |
| Magnetic bookcase | Critical | Use without magnet |
Program conflicts and third-party applications
Sometimes the culprit is not hardware, but software. Conflicts can arise between the phone system application and third-party downloaders or utilities to clean up memory. Aggressive MIUI optimization can kill the sensor process to save battery life.
It’s worth checking which apps have access to the phone and call management. If you’ve recently installed any number detector or call recorder, try temporarily removing it, and the app cache (Phone) can cause the problem, which grows over time and starts to malfunction.
To clear the cache, go to Settings → Apps → All Apps → Phone. Select Clear and press Clear Cache. Don’t be afraid to delete the cache – your contacts and call history won’t be affected, as they are stored in a separate database.
In some cases, resetting the network helps, which will return to the factory settings of Wi-Fi, Bluetooth and mobile networks, which can eliminate the software glitch that blocks the sensor.
Solving problems with ultramodern models
Owners of Xiaomi’s new flagships face a unique problem: their devices do not have a visible proximity sensor, such as the Xiaomi 12, 13, 14 Pro, which uses ultrasonic sensor technology embedded under the screen, which emits high-frequency audio and analyzes the reflection.
The thing about these sensors is that they're highly sensitive to software algorithms, and if you're using an informal firmware or a global version on a Chinese device, the driver of the ultrasonic sensor may not work properly, and in that case, standard CIT calibration may not work.
These devices often require upgrades to the latest version of MIUI or HyperOS, where engineers fix bugs in the subscreen sensors, and avoid using magnetic cables or charging during a conversation, as electromagnetic tips can (interfer) with ultrasound.
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For models without a visible sensor (under the screen), it is critical to use only original chargers and avoid extreme temperatures affecting the elasticity of components under the display.
⚠️ Warning: If after all the manipulations the screen goes out but doesn’t light up when you remove the phone from your ear, it may be a problem in sticking the mechanism or physical damage to the sensor plume.