The situation of suddenly turning off the phone screen during a conversation is familiar to many owners of Xiaomi and Redmi smartphones. Instead of completing a call or switching to speaker, you see a black display that does not respond to touch. It is not just an annoying bug, but often a consequence of the proximity sensor that mistakenly determines the position of the device in the ear.
Most of the time, the problem is software settings or sensor contamination, but sometimes you need to calibrate the system more deeply, and understand why you can quickly return the functionality to the gadget without going to the service center, and we'll go into detail about how the locking screen works and how to correct them.
It's worth noting that MIUI algorithms can behave differently depending on the firmware version, so if you have a screen go out when you call, it's important to check both the physical condition of the top of the case and the hidden engineering menus, sometimes just rebooting or removing the protective film is enough.
The principle of the proximity sensor on Xiaomi
The main culprit behind the screen going out is the infrared sensor at the top of the smartphone, which is designed to capture the distance to the object (your ear) and turn off the display to prevent accidental cheek pressing. On Redmi Note models and budget series, this sensor is often combined with a conversational speaker.
When you hold your phone to your face, the sensor picks up the IR reflection and sends a signal to the system to block the touchscreen, and if there's a malfunction in reading or contamination, the screen goes out ahead of time, and the algorithm can be disrupted even by changes in the environment.
There's also software emulation of the sensor, which uses data from the gyroscope and the accelerometer, and in these cases, the screen goes out when the device is tilted, but it's the physical sensor that is most often the source of problems because of its sensitivity to external factors.
⚠️ Warning: Using thick protective glasses or films covering the top of the screen often results in a false alarm of the sensor.
The main reasons for premature disabling of the display
If the screen goes out immediately after the bell starts, the first thing to do is to eliminate mechanical obstacles: Dust, greasy spots or glue residues from the previous film in the sensor area distort the signal, and even imperceptible pollution can be perceived by the system as an object in close proximity.
The second common cause is software conflicts: After an Android or MIUI update, some applications may get priority access to screen control, and third-party callers or conversation recording programs that incorrectly handle sensor interrupts also have an impact.
Physical damage is also not to be discounted, because a smartphone crash could cause the sensor plume to shift or fail completely, in which case the screen can either go out permanently or stop blocking during a conversation, leading to accidental tapping.
- 📱 Pollution of the upper speaker and sensor area with dust or fat.
- 🛡️ Inappropriate protective glass covering the IR port.
- 📲 Conflict of a third-party application with system call services.
- 🔋 Failures in the work of energy-saving modes that aggressively turn off the display.
Basic settings and application verification
Before you go to complex manipulations, you need to check the standard system settings. Go to the Settings menu → Lock and protect and make sure that the smart lock functions work correctly. Sometimes a simple restart of the device clears temporary files that cause errors in the operation of the sensors.
Notice the recently installed applications. If a problem occurs after you download new software, try to remove it. Especially often, antivirus programs, memory cleaners and alternative launchers, conflict, and they can intercept control of the display at the wrong time.
You should also check the settings of the phone itself. In the phone app (usually a handset icon), click on three dots or a gear in the corner and select Settings. Find "Mode in your pocket" or similar and try to change its state, which will help you understand whether the software protection affects the fact that the screen goes out.
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Try to put your phone in safe mode, and if the screen stopped going out spontaneously in this mode, then the problem is definitely in the third-party app.
Calibration of the proximity sensor through the engineering menu
The most effective method of solving the problem is manual calibration, which uses a hidden engineering menu available on most Xiaomi devices, and you need to open the Phone app and type in a special code that will open the hardware testing menu.
In the menu that opens, select "Proximity sensor." Press Calibration and follow the instructions on the screen. You usually need to cover the top of the phone with your hand and then remove your hand. The system will determine the sensitivity thresholds and store the new parameters.
##6484##After a successful calibration, press "Pass" or "OK" to save the results. If the test shows "Fail" even after several attempts, it may be that the sensor is physically faulty or heavily contaminated from the inside, in which case the software methods may not help, and the screen will continue to go out.
☑️ Calibration checklist
Resetting and system update
If calibration didn’t work, consider resetting network and application settings. This won’t delete your personal photos or contacts, but will return system configurations to factory values.The way to this feature is: Settings → Advanced Settings → Recovery and Reset → Reset Wi-Fi, mobile internet and Bluetooth.
Often the problem is solved by updating the firmware. MIUI developers regularly release patches that fix hardware errors. Check for updates in the Settings → About the phone menu. If you have a beta version installed, it is better to switch to a stable branch, since bugs are more common in test builds.
In extreme cases, you can perform a full data reset (Hard Reset).Be sure to back up all important files before that, this method removes all applications and settings, returning the phone to the "out of the box" state, which often eliminates deep software conflicts.
⚠️ Warning: A complete data reset will delete all files from internal memory. be sure to back up before starting the procedure!
Hardware problems and their solution
When software methods are exhausted and the screen is still going out, it's about hardware. A common problem with Redmi's budget models is the outgoing plume of the proximity sensor, and when you fall or vibrate, the contact can be disrupted, and the sensor begins to transmit chaotic signals about the presence of an object nearby.
And there's also a breakdown in the sensor module itself, and in this case, it's only the replacement of the component in the service center that helps, and sometimes the sensor is integrated into the charging port plume or the side button, which makes it difficult to diagnose, and if the phone is warranty, it's best not to open it yourself.
Another nuance is the use of non-original screens after repair: cheap copies of displays often have low-quality sensors or none at all (software emulation is used), which leads to incorrect work when calling. When changing the screen, always require original components.
| Symptoms. | Probable cause | Method of decision |
|---|---|---|
| The screen goes out in your pocket | High sensitivity of the sensor | Calibration or disabling the mode in the pocket |
| Black screen on the call | Sensor contamination | Cleaning of the upper part of the shell |
| It's not going out in the ear. | Sensor malfunction | Replacement of module in the service |
| Accidental cheekstrokes | Failure of the | Resetting settings or updating |
Why can the sensor lie?
Prevention and useful recommendations
That the black screen problem hasn't returned, follow simple rules of operation. Regularly wipe the top of the smartphone with soft cloth. Don't use too dense covers that hang over the display, creating a shadow for the sensor.
Periodically check the sensor through the engineering menu, especially after the phone falls. This takes a minute, but you can notice the drift readings in time. Also keep an eye out for system updates, as Xiaomi often improves the algorithms for working with iron in new versions of MIUI.
If you like to experiment with settings, avoid installing questionable tweaks from unknown sources, which can disrupt the system services responsible for managing power and display, and stability is more important than questionable customization functions.
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Timely calibration and cleanness of the proximity sensor in 90% of cases prevent problems with the fading screen during calls.