The situation when during a phone call or immediately after dialing a phone display suddenly goes out of a Xiaomi smartphone, familiar to many users. It is not just an annoying bug, but the result of the protection mechanisms of the Android operating system and the shell MIUI (or HyperOS), the main reason for this behavior is the operation of the proximity sensor, which locks the screen so that you accidentally press the cheek reset or turn on the volume.
However, if the screen turns off before you hold the phone to your ear, or doesn’t turn back on after the call is complete, it indicates a software failure or hardware malfunction. Owners of Redmi and Poco devices often experience incorrect sensor calibration, which makes the system “think” that the smartphone is in your pocket or ear.
In this article, we will discuss in detail why screen locks occur, how to distinguish between software glitch and breakdown, and also consider effective methods of setting up the sensor. You will learn what hidden engineering menus will help to conduct diagnostics, and whether you should be afraid of factory resets. Understanding the principles of proximity sensor will allow you to return the comfort of using voice communication on your device.
The principle of the sensor approach in smartphones Xiaomi
The main culprit behind dialing is an infrared proximity sensor, which emits invisible light and analyzes its reflection from nearby objects. When you bring the phone to your face, the light bounces off your cheek, the sensor detects the change and sends a signal to the PowerManager system to turn off the display. On current Xiaomi 13 or Redmi Note 12 models, this sensor is often hidden under the screen or integrated into the top bezel.
The problem arises when the sensor receives false signals, and this can be caused by contamination of the top of the screen, a protective glass with a wide black frame, or even a case that covers the touch zone, in which case the calibration is confused, and the phone locks the screen immediately after the call begins, preventing you from dialing an additional number or using loud communication.
It's important to understand that the Redmi series' budget models often use a virtual sensor paired with an accelerometer, which detects the position of the phone in space. If you hold the device horizontally or at a strange angle while dialing, the algorithm may misinterpret this as an ear-to-ear touch, which is why in some cases it helps to simply change the grip of the device or its position relative to the face.
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Before setting up, be sure to wipe the top of the screen with a microfiber - greasy spots often cause false sensor positives.
Software failures of the shell MIUI and HyperOS
Often the reason is not hardware, but software. The MIUI shells and the new HyperOS have a complex energy management structure. Sometimes the process that handles phone calls freezes or mishandles sensor data, which causes the screen to go out and no longer light up, even if you've removed the phone from your ear, and rebooting the device is the first and most effective solution.
Conflicts can arise after a system update. New firmware versions sometimes contain bugs that disrupt the standard Phone app. Users often notice that the problem occurred immediately after installing a security update or switching to a new version of Android.
You should also look at third-party apps that have access to screen or contact control. Different callers from the Play Market store, chat recording apps or number detectors can intercept the sensor. If you have multiple call apps installed, try removing those that are unnecessary and leaving only the com.android.dialer system app.
⚠️ Warning: Do not install questionable apps for “phone speeding” or “battery calibration” from unverified sources.They often contain ad modules that conflict with Xiaomi’s system processes and cause random screen behavior.
How to check and calibrate the proximity sensor
If the screen goes out, you need to do a diagnostic. Xiaomi smartphones have a built-in engineering menu to check all the components. To get there, open the Phone app and dial the code ##6484#. In the menu that opens, select "Proximity sensor." Here you will see the current value: if it changes from 5.0 to 0.0 (or vice versa) when you bring your hand to the top of the screen, then the sensor is good.
If the values don't change or change randomly, you need calibration. In the same engineering menu, there's often a Calibration button. Press it and follow the instructions on the screen: usually close the sensor with your hand, then remove your hand and press the confirmation. After successful calibration, the phone vibrates and the screen blinks. This action resets the threshold values of sensitivity.
To get a deeper setup, you can use the Engineering Mode app (APK installation is required if hidden in the system). Under Single Item Test, select Proximity Sensor and press Calibration. Make sure the front panel is clean and nothing closes the top of the display during the process. After calibration, be sure to restart the device to make the changes take effect.
☑️ Testing of the proximity sensor
Screen settings and locks when calling
There are settings in the system that directly affect the display behavior during a call. Go to Settings → Lock screen and check if Pocket mode is activated. If it is on, the phone will aggressively lock the screen at the slightest dimming, believing that it is in your pocket.
You should also check the settings of the Phone app itself. Open it, click on three dots or a gear of settings, and find the Incoming Calls section. There may be an option to turn on the screen when a call comes in or similar. Make sure all the switches associated with the approach response work correctly. On some versions, MIUI helps reset the Phone app to factory settings.
Special attention should be paid to the “Increase in your pocket” or “Mode in your pocket”, which prevents accidental clicks. If this function is not working correctly, it can lock the screen immediately after dialing. Try temporarily disabling all the functions related to protection against accidental clicks in the Settings → Screen menu to identify the culprit.
| Parameter | Where to find out. | Recommended value | Impact on the problem |
|---|---|---|---|
| Pocket regime | Settings → Lock screen | Off (for test) | High: Often causes false blockages |
| Sensor resolutions | Settings → Applications → Phone → Permissions | Permitted. | Critical: without access, the sensor does not work |
| Saving energy | Settings → Battery | No restrictions. | Medium: Can turn off the sensor to save money |
| Dark subject matter | Settings → Screen | If you wish, | Low: Rarely, but affects brightness calibration |
Influence of protective glasses and accessories
One of the most common but common causes is poor-quality security glass. If the black glass frame overlaps the sensor area (usually a narrow strip at the top of the screen or a hole in the speaker), the sensor goes blind. It constantly sees the "object" (the glass frame) and keeps the screen off. The solution is one - replacing the glass with a model with a cutout for the sensor or a smaller frame.
Tight bookcases or bumpers with high sidebars can also create shadows over the sensor, especially for models with a front-facing hole camera, where the sensor is placed in the thinnest frame above the screen. Take off the case and see if the problem has gone away. If the screen stops going out spontaneously, the accessory is to blame.
Sometimes it helps to have a software solution for the owners of protective glasses, and there are calibration applications that allow you to artificially understate the sensitivity of the sensor so that it ignores the close proximity of the glass, but this is a temporary measure, and it is better to replace the accessory with a compatible one.
⚠️ Warning: When replacing the security glass in the service, require that the wizard test the proximity sensor before assembly. The glue used in the installation can leak into the speaker's grille and lock the IR emitter permanently.
Radical measures: resetting and reflashing
If the software settings and calibration didn’t help, there may have been some critical errors in the system, in which case it is recommended to reset to factory settings. Be sure to back up your data to the Google or Mi Cloud cloud before doing so. Reset will remove all apps and settings, returning the phone to the “out of the box” state, which often eliminates deep driver conflicts.
In extreme cases, when a problem has occurred after a failed update, flashing the device helps, and you can do this through the Mi Flash Tool on your computer by selecting Clear All mode. It is important to download the firmware specifically for your model and region. Incorrect firmware can cause the communication module to break.
Even if you've completely flashed and reset the screen, and it's still going out when dialing for no apparent reason, there's a high probability of hardware failure, which could be a sensor plume, contact oxidation after moisture, or the sensor itself, and in that situation, the software is powerless, and you need to visit the service center.
Should I bring my phone to the service?
Frequently Asked Questions (FAQ)
Why does the screen go out even when I don’t hold my phone to my ear?
Can I completely disable the proximity sensor on Xiaomi?
Does the sensor have an effect on the taped film?
What if the screen doesn’t light up after the conversation is over?
Is it true that the new Xiaomi doesn’t have a physical sensor?
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In 80% of cases, the problem is solved by simply cleaning the top of the screen and recalibrating the sensor through the engineering menu, without the need for a data reset.