When the screen of Xiaomi phone goes off during a conversation, it is one of the most common and annoying problems for owners of devices based on MIUI and HyperOS. You dial the subscriber number, hold the smartphone to your ear, and the display safely turns off, as expected by engineers to save energy. However, when you take the device away from your face, the screen continues to remain black, and you can not finish the call, turn on speakerphone or use loud communication.
Most often, this behavior is caused by a misfunctioning proximity sensor, which is located at the top of the body, which should respond instantly to changes in the distance to the object, but due to software failures, contamination or features of the protective glass, it can stick in the locking state, as a result, the system continues to think that the phone is still in your ear, and forcibly keeps the display off.
In this article, we will discuss in detail all possible reasons why the screen goes out on Xiaomi, and offer step-by-step solutions - from simple cleaning to hidden engineering tests. Xiaomi often changes the location of sensors in different models, so it is important to understand the specifics of your device, whether it is a budget Redmi Note or flagship Mi. We will consider both software settings and physical factors that affect the operation of the device.
Principle of operation and location of the proximity sensor
To deal effectively with a problem, you have to understand the physical nature of the process. The proximity sensor is an infrared sensor that consists of an emitter and a receiver. When you bring the phone to your face, the emitter emits an invisible beam that bounces off your cheek and hits the receiver. The system receives a signal that the distance is less than a given threshold, and sends a command to turn off the display.
On modern Xiaomi and Redmi smartphones, this sensor can be inserted into a separate hole next to the speaker or integrated directly into the screen matrix (virtual sensor). In the first case, the problem is often in the contamination of a small hole. In the second, in software calibration, since virtual sensors are sensitive to pasted protective films and thick cases.
The key is the accuracy of the reading. If there is an obstacle in the path of the beam (dust, grease, glass edge), the receiver detects the reflection even when the phone is in the hand 20-30 cm from the face, which leads to false alarms and locking the screen.
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Owners of models with screens-"waterfalls" or curved edges should be especially careful in the choice of covers, as they often overlap the area of operation of virtual sensors.
The main reasons for blocking the display during the call
The list of reasons why the screen goes out when called is wide enough, ranging from trivial inattention to serious hardware malfunctions. The first thing to do is to rule out external factors. Low-quality protective glass without a special sensor cutout is the number one reason. Even if there is a cutout, but the glass is thick or has a black frame around the perimeter, it can block the sensitive area.
The second common cause is a software failure in the MIUI shell. System updates sometimes "break" sensor drivers, which causes them to stop calibrating correctly after turning on the phone.
The third group of causes is related to the physical condition of the device: Falls, moisture or simply the accumulation of dirt in the dynamic grille can disrupt the hardware part. In rare cases, the problem lies in the departed plume connecting the board to the top of the case, which often happens after unqualified repairs.
- 😐 Protective glass: Incorrectly pasted film or glass with black fields overlap the sensor.
- 📱 Case: Too high side of the case in the upper part of the smartphone closes the touch zone.
- 🦠 Pollution: A buildup of dust, pile, or skin fat in the area of the talking speaker.
- 🔋 Overheating: When heated during a long conversation, the system may not properly process sensor readings.
Basic cleaning and inspection of accessories
Before you go into deep settings or bring your phone to the service, you need to do a thorough audit of external accessories, remove the protective case and try to make a test call. If the problem disappears, then the accessory was the culprit, many users do not even suspect that their favorite silicone bumper covers the micro-hole of the sensor.
Then you have to look carefully at the security glass. If it has a black frame around the perimeter, make sure that it does not go to the sensor area. In Redmi and Poco models with a cut-out drop, the sensor is often directly above the screen, and the slightest shift in the glass leads to blocking. It is also worthwhile to wipe the top of the smartphone with an alcohol napkin, removing fatty traces.
If you use universal protective glass, it may not have the exact cutouts for your model, in which case the only solution would be to replace the glass with the original or specialized (3D/5D) with the right cutouts, and ignoring this point will lead to constant problems with shielding during the conversation.
⚠️ Warning: Do not use aggressive chemistry or abrasive materials to clean the sensor area.This may damage the oleophobic coating or the sensor element itself.
Engineering menu and calibration of the proximity sensor
If physical methods don't work, you need to move to software calibration. Xiaomi smartphones have a hidden engineering menu. CIT, It allows you to test all the modules of the device. USSD-Open the Phone app and dial the combination ##6484##.
In the menu that opens, look for the Proximity Sensor. Click on it. You'll see two values: Distance and Status. Cover the top of the phone with your palm, the Distance value should change from 5.0 (or max) to 0.0, and the status should switch to "Near." If it doesn't, the sensor doesn't see the obstacle or, conversely, "slip."
Recalibration is often required to rectify the situation. In some versions of MIUI, there is a Calibration button inside the test. Press it, remove your hand from the sensor and wait until the process is complete. If automatic calibration is not available, you can try resetting the sensor settings through the developer menu or special applications from the Play Market, although the built-in MIUI tools are usually more efficient.
☑️ Checklist of diagnostics in CIT
Importantly, newer firmware versions may have limited access to some tests. If the code doesn't work, try typing ##4636## and searching for information in the "Phone Information" section, although sensor tests are less common, the main goal being to get a clear sensor response to the object's approach and removal.
System settings and special features
Sometimes the problem isn't with the sensor itself, but with how the system processes its signals. Android and MIUI have features that can conflict with standard screen behavior. Check the Accessibility section, which can activate Remote Control or similar services that intercept screen control.
Also worth paying attention to lock settings. Go to Settings → Lock screen and check if aggressive power saving modes are on for the screen. In some cases, disabling Pocket Mode if it is not working correctly helps. This feature is designed to prevent accidental taps in your pocket, but can mistakenly lock the screen when you call.
Another important aspect is system updates. If the problem has occurred after the MIUI update, there may be a bug in the new version. Check the forums or reviews about your model. Often Xiaomi releases patches that correct such errors. While waiting for the update, you can try to clear the cache of the Phone and MIUI System Services app.
| Parameter | Normal value. | Problematic significance | Action. |
|---|---|---|---|
| Distance (CIT) | 0.0 (hand) / 5.0 (no hand) | Constantly 0.0 or 5.0 | Calibration/Cleaning |
| Protective glass | There's a cutout under the sensor | A solid or black frame | Glass replacement |
| Cover | It doesn't cover the top. | High boards. | Remove the case |
| Pocket mode | Off (for test) | Included | Turn off in the settings |
Hidden Developer Settings
Third-party applications for sensor control
If Xiaomi’s regular tools don’t work, third-party apps come to the rescue. There are many tools available in the Google Play Market for calibrating and testing sensors. One of the most popular is “Proximity Sensor Reset/Fix,” which allows you to force the sensor driver to restart without rebooting the entire phone.
Another useful application is the Phone Sensor, which provides detailed information about the current status of all sensors in real time, and it can track whether the sensor is constantly bugging or only in certain conditions (such as in bright sun or in the dark), which will help to better diagnose the problem.
However, be careful: installing too many applications with deep access to the system can lead to conflicts. Use only proven utilities with high ratings and a lot of installations. After using such applications, it is recommended to remove them so that you do not waste battery resources in the background.
⚠️ Note: Applications that require root-right to calibrate are only used if you are confident in your actions. Incorrect editing of system files can lead to complete inoperability of the communication module.
Radical measures: dumping and repair
When software methods are exhausted, there are two options: a complete reset or repair. A factory reset (Settings → About Phone → Reset) deletes all data and returns the system to its original state. This eliminates the impact of third-party applications and accumulated system debris. Be sure to back up important data before the procedure.
If even after the reset, the screen goes out and doesn't turn on, it's probably hardware, it could be a sensor malfunction, a plume break, or a motherboard problem, and it requires disassembly of the device, and it's hard to change the sensor on your own, because it's often soldered into a charging plume or a display module.
Contacting an authorized Xiaomi service center is the most reliable option, specialists will diagnose the multimeter and replace the defective component. If the phone is warranted, repair will be free, provided that there are no signs of autopsy or mechanical damage to the case.
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If after a complete system reset and check in the engineering menu (CIT) sensor shows incorrect data, the problem is hardware in nature and requires replacement of the part.