Modern Xiaomi smartphones are equipped with many smart features designed to simplify interaction with the device. One of these features is automatic locking of the screen during a phone conversation. This prevents accidental pressing of buttons with the cheek or ear, which could interrupt the call or activate unnecessary actions. However, users often face a situation where the screen continues to burn, preventing comfortable communication, or, conversely, goes out too early.
The problem can lie in both the software settings of the MIUI operating system and the hardware features of the proximity sensor. Understanding how this mechanism works will allow you to quickly fix the situation without going to the service center. In this article, we will discuss in detail how to activate the lock, why it may not work, and what hidden settings exist for advanced users.
It’s worth noting that the behavior of the system can vary depending on the firmware version and the specific model of your device. For example, on Xiaomi’s flagship series and Redmi’s budget models, the algorithms for processing data from the sensors may differ.
The principle of operation of the proximity sensor in MIUI
The main thing that's going to quench the display is the proximity sensor, which is a small sensor that's sitting at the top of the screen, usually next to the speaker, and it's going to be able to tell the distance between the surface of the smartphone and the object that's in this case your head, and when you hold the phone up to your ear, it picks up the light change or the reflection of the infrared beam and sends a signal to the system.
In Android, the MIUI-enclosed operating system, the system process (Phone) is responsible for processing this signal. If everything is working correctly, the screen instantly goes out, going into sleep mode, but communication is not interrupted. Once you remove the phone from your ear, the sensor detects the absence of an obstacle, and the screen lights up again, allowing you to use a loud communication or keyboard to set the tones.
Sometimes, software misinterprets sensor data, which can be caused by a protective film covering the top of the screen, or a software failure in the drivers, and it's important to understand that the sensor doesn't "see" through opaque materials, so any contamination in that area can cause a malfunction.
- 📡 The sensor uses infrared radiation to determine the distance to the object.
- 📱 The location of the sensor varies: in old models it is under the screen, in new ones - in the cutout or drop-shaped indentation.
- ⚙️ Software calibration allows you to adjust the sensitivity of the operation.
Technical nuances of the sensors
Basic settings through the call menu
The first thing to do when you have a problem is to check the standard settings of the Phone app, and in the MIUI shell, the developers have a separate switch that controls the lock function, and if it's turned off, the screen will burn throughout the conversation, regardless of the position of the phone.
To access the settings, open the Phone app and click on the three dots in the top right corner or select Settings in the menu. Here you need to find the section related to incoming calls. The interface may vary slightly depending on the version of MIUI, but the logic remains the same.
Find incoming call settings or just Incoming calls. Inside this menu should be a switch called Random Press Lock or Approach Sensor. Make sure it's activated. If the switch is already on but the problem persists, try turning it off, restarting the device and turning it on again.
☑️ Checking basic settings
It should be remembered that some third-party applications for calls (for example, from Google or Truecaller), if they are installed as the main, may have their own settings that ignore the system parameters of Xiaomi.
Calibration of the approximation sensor with engineering code
If standard settings don’t help, it may require recalibration. Xiaomi smartphones have a hidden engineering menu that allows you to test and customize various hardware components, the most effective way to solve the problem when the screen goes out in your pocket or does not go out in your ear.
To enter the engineering menu, open the Phone app and type a special code. Enter the sequence of characters: ##6484##. Immediately after entering the last star, the CIT menu will open. Here is a list of all the components of your device being tested.
In the list, look for the Proximity Sensor. Click on it. You'll see a screen with numerical values and control buttons. Put your phone on a flat surface or cover the top of the screen with your palm, simulating a conversation. The value should change from 5.0 to 0.0 (or vice versa, depending on the version of the test). If there is no reaction, the sensor may be physically malfunctioning.
To perform the calibration, press the Calibration button. Follow the instructions on the screen: usually you need to close the sensor first (cover with your hand), and then open it. Once the procedure is completed successfully, a success message will appear. Reboot your smartphone so that the changes take effect.
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If the ##6484## code doesn’t work, try the alternative type: ##4636##. However, the first code is standard for most Xiaomi and Redmi devices.
Resolving conflicts with protective accessories
One of the most common reasons for screen locking to work is because of protective glass and film. Accessories manufacturers don’t always take into account the exact location of sensors in specific Xiaomi models. If the protective glass covers the sensor area, it creates a permanent “shadow” and the phone thinks it is in the ear all the time.
Carefully examine the top of the screen when the display is off under bright light. You should see the little black window of the sensor. If the security glass covers this area or has an opaque frame there, this is the source of the problem. In such cases, the screen can go out immediately after the start of the call, even if the phone is lying on the table.
Also, the problem can be caused by cases with magnetic fasteners or too thick bumpers that shift the position of the phone in the hand, causing the finger to overlap the sensor during a conversation.
| Accessory type | Probability of conflict | Recommended action |
|---|---|---|
| Frameless protective glass | Tall. | Replacement with glass without frame or with a cutout |
| Hydrogel film | Low. | Checking the quality of the sticker in the sensor area |
| Magnet-book case | Medium | Use of a cover without magnetic fastener |
| Transparent silicone bumper | Low. | Controlling the position of the fingers when calling |
If you don't want to shoot high-quality protective glass, you can try software to increase the sensitivity of the sensor, although in standard MIUI settings this option is not. The only solution is to use the engineering menu described above, or replace the accessory with a compatible one.
Impact of System Updates and Third Party Applications
Updating the MIUI operating system often brings not only new features, but also bugs. After a major update, users often notice that the usual functions start to work differently, this is due to a change in drivers or conflict of old settings with the new version of the firmware.
In addition, third-party applications with access to call management can intercept the sensor. Antiviruses, ad blockers or conversation recording applications can block the standard screen-canceling mechanism. Check the list of newly installed applications and try to turn them off temporarily.
The Pocket Mode feature is particularly noteworthy, and in some versions of MIUI, it is aggressively implemented and can lock the screen without even close touch to the head, relying on accelerometer data, and disabling this feature in lock settings can solve the problem of false positives.
⚠️ Note: If the problem occurs immediately after the system update, do not rush to reset the settings. 20-30 minutes of active phone operation - the system conducts background optimization of applications, which can temporarily affect the operation of sensors.
In rare cases, cleaning the cache of the Phone and Contacts app helps. To do this, go to Settings → Apps → All apps, find Phone, select Memory, and click Clear Cache. This will not delete your contacts, but will reset temporary files that may have been corrupted.
Diagnostics of hardware faults
If neither software tweaks, calibration, or removal of the safety glazings worked, there is a high probability of hardware failure, and the proximity sensor is a physical component that can fail due to a fall, moisture, or factory defect, and unlike software failure, more radical measures are required.
The symptoms of hardware malfunction are often permanent: the screen either never goes out when it is brought to the ear, or it goes out forever and doesn't turn on until you press the power button.
For final diagnosis, you can use special applications from Google Play, such as Sensor Test or Phone Sensor, which show the sensor's schedule in real time, and if the graph does not respond to the movements of the hand above the top of the screen, the problem lies in the hardware.
- 💧 Moisture intake is a common cause of oxidation of sensor contacts.
- 🔨 Mechanical impacts can damage the plume connecting the sensor to the motherboard.
- 🔋 Bloating the battery sometimes leads to displacement of internal components and detachment of plumes.
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If the sensor test shows the value of Fail in the engineering menu or the data does not change when the screen is closed with your hand, you need to replace the sensor or plume in the service center.
Frequently Asked Questions (FAQ)
Why does the screen go out when I just hold my phone in my hand without touching my ear?
Can I turn off the screen completely when talking?
Does the sensor work with the ambient temperature?
What if the sensor stopped working after calibration?
⚠️ Warning: Do not use third-party applications to "amplify" the sensor signal from unverified sources. MIUI And lead to unstable operation of the entire smartphone.
To sum up, setting up a lock screen on Xiaomi is a process that requires you to consistently rule out possible causes. Start by checking the settings and removing the protective films, then proceed to calibrate. Only a comprehensive approach will return the comfort of using your smartphone during conversations.