The situation when the screen goes out during a conversation and does not light up when you remove the phone from your ear is familiar to many owners of Xiaomi, Redmi and Poco smartphones. This is not always a sign of breakdown; most often the problem lies in the incorrect operation of the proximity sensor or the software settings of the MIUI operating system. Users often confuse a software failure with physical damage, although the solution usually lies in hidden engineering menus or the correct location of accessories.
In this article, we will take a look at how the display shutdown mechanism works, why it sometimes crashes, and how you can force it to work. You will learn how to professionally calibrate the sensor, whether to remove the protective glass, and what hidden developer features can help solve the problem. Understanding these processes will help you avoid unnecessary trips to the service center.
The main reason Android turns off the screen when you bring the device to your face is to save battery power and prevent accidental cheekstrokes. However, if the sensor is contaminated or closed, the phone thinks it's still in the ear and blocks the image. Customizing this setting requires care, because doing the wrong thing can cause the screen to stop going out altogether, which is also uncomfortable.
The principle of the proximity sensor on Xiaomi
The functionality is based on a special sensor, which is usually located at the top of the front of the smartphone, next to the conversational speaker. On modern Xiaomi models, a virtual sensor is often used, paired with an accelerometer and a front camera, making it more sensitive to software errors.
When you hold the phone to your ear, the sensor detects the change in distance and sends a signal to the system to lock the touchscreen and display. If the call interface is displayed on the screen at that moment, it immediately goes out. Problems begin when the proximity sensor receives false signals due to dust, grease or improperly installed protective glass, in which case the system cannot correctly determine whether the phone is in the ear or in the hand.
It is important to understand that MIUI software takes precedence over hardware signals, which means that even a good physical sensor can malfunction due to firmware bugs or conflicts with installed applications, and users often notice that after a system update, the problem appears or disappears, which confirms the software nature of many failures.
⚠️ Warning: If the top of the screen is covered with a tight case with high sides or a thick protective glass with a black frame, the sensor can constantly "see" the obstacle, in which case the screen will go out immediately after the call begins, even if the phone is lying on the table.
To diagnose a primary sensor state, you don't have to go straight to complicated menus, just call someone and hold your finger to the top of the screen, mimicking a conversation, and if the screen goes off instantly and lights up immediately after you remove your finger, the hardware is good, and the problem is probably the settings or the software.
Basic inspection and calibration through the engineering menu
The most reliable way to test and adjust the sensor is to use the built-in CIT (Customer Integration Test) menu, which is available on all Xiaomi smartphones and allows you to accurately calibrate by resetting accumulated measurement errors.
To get into testing mode, open the standard Phone app and dial the combination ##6484##. Once you enter the last digit, the test list will automatically open. You need to find the Prox. sensor and click on it, and you will see a window with numerical values that change when you close the top of the screen with your hand.
☑️ Testing the sensor in CIT
In the test window, you'll see two values: the current and the threshold. If the numbers don't change or change incorrectly when you put your hand up (e.g., 0.0 is constantly), you need to calibrate. Press Calibration and follow the instructions on the screen: normally, you should remove your hand, wait for the green indicator, and then close the sensor again.
Once calibrated successfully, the system will overwrite the base values of the sensor into memory, which often helps if the screen has stopped dimming or, conversely, goes out for no reason, but if after calibrating the values in the CIT menu, the values still jump or do not respond, the problem may be deeper — in hardware or system conflict.
⚠️ Warning: Do not interrupt the calibration process until it is complete. If you turn off the screen or start another application during the procedure, the settings may be confused, which will lead to incorrect operation of the sensor in the future.
It is worth noting that on some global firmware versions, the login to the engineering menu can be blocked by the carrier or manufacturer, in which case you can try the alternative code ##4636##, although it contains fewer settings for hardware. If none of the code does not work, you will have to use third-party apps from Google Play to test the sensors.
Sensitivity settings in hidden settings
There's a hidden parameter in the MIUI-based Android operating system that regulates the sensitivity of the proximity sensor, which is not displayed in the usual settings menu, but is available through the Engineering Mode app, which can be downloaded from the app store, a technique that is particularly relevant for models where the sensor is virtual.
After installing and running the Engineering Mode app (or similar, for example, MTK Engineering for MediaTek processors), go to the Telephony or Phone tab. Find the Proximity Sensor or PS section. Here you will see a slider or numerical value responsible for the trigger threshold, changing this parameter makes the sensor more or less sensitive to the phone's removal from the ear.
If the screen goes out too early when the phone is far from the face, the sensitivity needs to be reduced. Conversely, if the screen only lights up when the phone is already 10 centimeters from the cheek, the sensitivity should be increased. Experiment carefully, changing the values in small steps and checking the result with a real call.
Risks of changing engineering settings
Some versions of MIUI (especially in Chinese firmware) have the option to “Increase Sensor Sensitivity” right in the standard settings. To find it, go to Settings → About Phone → MIUI Version (click 7 times to activate Developer Mode), then Advanced Settings → For Developers. Look for the item associated with “Proximity” or “Proximity Sensor”.
Remember, software sensitivity settings won't help if the sensor is physically closed. Virtual calibration only corrects the algorithms, but it can't break through thick glass or a layer of glue. So, before you climb into the engineering menus, always conduct a visual inspection of the top of the smartphone.
Influence of protective glasses and accessories
One of the most common causes of screen problems during a conversation is poor-quality protective glass or film. Many users, wanting to protect the display, buy glasses with a wide black frame that covers the area of the sensor, even if it seems visually that the glass is transparent above the sensor, the glue layer or the structure of the material itself can distort infrared radiation.
If you recently put on a new security glass and immediately after that the screen stopped working normally when calling — the reason is almost certainly this. The proximity sensor on Xiaomi is often located very close to the edge or integrated into the speaker, and the slightest obstacle is critical, in which case the system receives a constant signal that the object is nearby, and locks the screen.
- 😐 Problem: Black glass frame closes the sensor – the solution: replace the glass with a model with a cutout for the sensor.
- 🧼 Problem: Fat spots or dust in the speaker area - solution: wipe the top of the screen with an alcohol napkin.
- 📱 Problem: Case with high sides presses on the screen - the solution: remove the case during a conversation or replace the accessory.
It is also worth considering that over time, the glue on the protective glass can become cloudy or peel off, creating additional interference. If the glass is not possible to remove, some users use a software crutch: turn off the proximity sensor through special applications (for example, Proximity Sensor Fix), but then the screen will only go out on a timer or button, which is less convenient.
Using cheap analogs often leads to the problems described above. If you don’t want to give up protection, look for glasses marked “Compatible with Proximity Sensor” or “Sensor Compatible.”
Comparison of problem-solving methods
There are many ways to try to correct a situation where the screen behaves unpredictably, but not all methods are equally effective and safe. Below is a table that will help you choose the best way to solve the problem depending on your symptoms and your readiness for technical manipulation.
| Method of decision | Difficulty | Efficiency | Risks. |
|---|---|---|---|
| Cleaning speaker and sensor | Low. | High (if the cause is mud) | Absent. |
| Calibration via CIT (#6484##) | Medium | Tall. | Minimum |
| Replacement of protective glass | Medium | High (if the cause is glass) | Possible damage to the screen when removed |
| Setup in Engineering Mode | Tall. | Medium | Failure of system settings |
| Third-party applications (Fixer) | Low. | Low/Mediocre | Advertising, access to personal data |
As you can see from the table, it is always the easiest and safest way to start: Physical cleaning and checking accessories take a couple of minutes, but solve the problem in 50% of cases. Calibration through CIT is the gold standard diagnostics that every Xiaomi owner should try for such symptoms.
Using third-party apps should be seen as a temporary solution or a crutch if other methods have not worked, often requiring permanent permits to work in the background, which can negatively affect the autonomy of the smartphone, and they do not treat the cause, but only bypass the locking mechanism.
💡
The most efficient algorithm: first clean the sensor, then check the protective glass, and only then conduct a software calibration through the CIT.
What to do if the screen does not go out at all
The reverse of the screen being turned on while you're talking is also uncomfortable, and in this case, you're constantly hitting the dial digit, reset button, or volume, and not only is it annoying, it can lead to an accidental end of an important conversation or to the speakerphone at the wrong time.
Most often, the reason is that the approach sensor is blind and can't see objects, and this can happen after a fall, moisture or severe contamination. If the CIT calibration shows that the sensor is not responding to the hand (values do not change), you may need to change the hardware module or the plume, especially if the phone is waterproof and sealed.
As a temporary solution, you can use the “Respond to swipe” function or voice control to minimize touching the screen, and it also helps to enable “In your pocket” mode in lock settings, which uses other algorithms to determine the position of the phone, although it does not always work correctly during the call.
If you use a third-party caller (like Google or Truecaller), try switching to the standard MIUI Dialer app. Third-party apps may have conflicts with sensor drivers, especially on older versions of Android. In the Phone app settings, it is also worth checking if the Approximation Sensor feature is disabled (sometimes this option is found in simplified builds).
⚠️ Note: If the screen does not go out and the phone is very hot at the top during the conversation, this may indicate a short circuit in the sensor circuit.