The situation where Xiaomi smartphone completes a call but the display remains black is one of the most common complaints users have.This can occur on both new flagships and budget Redmi models. The main reason for this behavior is usually the incorrect operation of the proximity sensor, which locks the screen while talking to the ear to prevent accidental cheek pressing.
However, if the screen does not unlock after the call is over, it creates serious discomfort: you have to force the device to restart or wait until it itself comes out of sleep mode. In most cases, the problem lies in a software failure or contamination of the upper body, but sometimes the calibration of the sensor or physical damage to the protective glass is to blame.
In this article, we will take a look at all the possible causes, from the most trivial to the most complex hardware malfunctions, learn how to set up the system correctly, use the engineering menu for testing, and understand when it is time to carry your phone to the service center. Ignoring the problem can lead to you missing an important re-calling or not being able to reset the call.
The mechanism of the proximity sensor in MIUI
To understand the problem, you need to understand how the proximeter works in the MIUI shell, which is an infrared sensor at the top of the screen that emits an invisible beam and reads its reflection, and when you hold the phone to your ear, the beam bounces off your cheek, and the system receives a signal to lock the display.
The problem is when the sensor sticks in the "object nearby" state, at which point MIUI thinks the phone is still in your ear, and forces the screen to be turned off, a protective mechanism that normally saves battery power and prevents chaotic taps.
Sometimes the sensor controller doesn't have time to respond to the end of the conversation, so even after you've removed the phone from your face, the screen is still black, and this is made worse by virtual proximity sensor models, where the sensor is a software algorithm that analyzes data from the accelerometer and gyroscope.
How to distinguish a virtual sensor from a physical sensor?
Main programmatic causes of failure
The most common cause is a conflict of operating system versions or an error in the operation of a specific Android update. After installing a new version of MIUI, the sensor settings can be reset or misinterpreted by the system, and the culprit can be the cache of the Phone application, which accumulates errors during long-term operation.
Another important aspect is the operation of background processes: If a critical amount of resources is occupied in memory, the system may simply "forget" to send a command to turn on the backlight after the call is completed, this often happens on devices with a small amount of RAM, where background services are unloaded aggressively.
And you can also use third-party applications, because various cleaners, antiviruses, or conversation recording applications can take over the proximity sensor, and if you installed this software shortly before the problem occurred, try removing it and checking your calls.
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Use Safe Mode for diagnosis, and if the screen lights up normally after the call, it means that the problem is in one of the apps you have installed.
Physical factors and protective accessories
Often, the problem is much easier than it seems. The most common cause is contamination of the top of the screen. Fat spots, dust or moisture in the area of the dynamic conversational speaker can block the infrared radiation of the sensor, which results in the sensor “thinking” that the object is still nearby, and prevents the screen from catching fire.
The second common factor is the wrong protective glass or film, and if the accessory has a black frame that goes into the sensor area, or is simply glued with a skew, the proxy will be disrupted, and even a microscopic crack in the sensor area can lead to incorrect readings.
It’s also worth checking if the phone has a thick sticker or a case with high sides that physically prevent the sensor from “seeing” the space in front of it, in which case the screen can behave unpredictable, turning on with a delay or not turning on at all.
☑️ Physical factors check
Diagnostics through engineering menu and tests
To accurately determine the status of the sensor in Xiaomi smartphones, there is a built-in engineering tool that allows you to check the operation of all sensors without installing third-party software. To start the diagnosis, you need to enter a special code in the application for calls.
Type ##6484## into the dialer. The CIT menu will open. In the test list, look for "Proximity Sensor" or "Proximation Sensor." If you click on it, you'll see the current reading. Put your hand to the top of the screen, and the value should change from 5.0 (or Near) to 0.0 (or Far).
If the values do not change or change with a long delay, this indicates a hardware problem or a need for calibration. In the same menu, the Calibration function is often available. Follow the instructions on the screen: usually you need to close the sensor with your hand and then remove it.
| Parameter | Normal value. | Failure value | Description |
|---|---|---|---|
| Status | Near / Far | Always near. | Indicates if object is close |
| Distance (see para. | 0 - 5 cm | > 5 cm (when closed) | Distance to object |
| Raw Data | Change. | It doesn't change. | Raw sensor data |
| Light Sensor | Active. | 0 | Light sensor (often paired) |
Calibration methods for the proximity sensor
If the diagnostics show abnormalities, but the sensor is physically intact, it needs calibration. In modern versions of MIUI, this process is often automated, but you can try forced resetting of the sensor settings, which is especially true after replacing the display module or glass.
The first way is through the same CIT engineering menu: Select the Proximity Sensor test, press Calibration and follow the instructions strictly. Usually, the system will ask you to close the sensor (the message will appear "Put phone in pocket" or similar), and then open it. After successful passage, the inscription "Pass" will appear.
The second way is to completely reset your settings through the Recovery menu, but this is an extreme measure that requires data backup. Often, just rebooting with cache cleaning helps. To do this, turn off your phone, press the power and volume button (the combination depends on the model), select Wipe Cache (not to be confused with Wipe Data).
⚠️ Note: Do not try to calibrate the sensor if the screen is thick protective glass with a wide frame. Calibration will be successful, but the sensor will not work properly due to the accessory.
System settings and applications Phone
In some cases, the problem lies in the settings of the Phone app itself from Google or Mi Dialer. Check if the Mode in Your Pocket feature is enabled in the lock settings if it conflicts with the sensor.
To do this, go to Settings → Apps → All Apps → Phone. Click Clear and select Clear All Data. Don’t worry, contacts and call history (if they’re synced to your account) won’t be lost, only the app settings will reset.
Another important item is to update the system components. Go to Settings → About the phone and click on the version of MIUI. Check for updates. Often Xiaomi releases patches that fix exactly the operation of the sensors and the stability of communication.
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Cleaning up the phone and Google Play services data solves the problem 60 percent of the time if the sensor is physically fit.
Hardware malfunctions and repairs
If the software and calibration didn't work, there's probably a hardware breakdown, which could be a sensor plume that's gone off the board (often after a fall), or the sensor itself that's gone down. In models with a cutout in the screen (bangs), the sensor is built right into the matrix, and it requires replacing the entire display.
In separate module models (like the Redmi Note 8, 9 and some Poco), the sensor is a separate small part on the plume, and it costs a lot of time to replace it, but if the phone gets into water, the contacts on the main board can oxidize.
It's hard to diagnose a hardware problem at home without disassembly, if after resetting to the factory settings (Hard Reset) and flashing the problem persists with the same persistence - the way one, to the service center.
⚠️ Attention: Self-disassembly of modern Xiaomi smartphones can lead to loss of water protection (if any) and damage to the plumes. If you are not confident in their abilities, it is better to entrust the repair to professionals.
Interim solutions and workarounds
Until you solve the problem, you can use temporary crutches to make your phone comfortable, and the easiest way is to use a speakerphone or headset (Bluetooth or wired), in which the proximity sensor is often ignored or works differently, and the screen does not go out.
You can also turn on the "Raise to turn on" or "Double touch to turn on." If the screen goes out after the bell, just take the phone in your hand or touch the screen twice - this will force the system to question the sensors and unlock the display.
Another option is to install an alternative app for calling from Google Play (like Truecaller or Simple Dialer), which can handle the proximity sensor interrupts differently and not lock the screen as aggressively as a standard “call.”