The situation when the smartphone receives an incoming call, but the display remains black, is one of the most annoying problems for users of Xiaomi, Redmi and Poco. You hear the ringtone sound or feel the vibration, but it is impossible to answer the call, since the call interface is not displayed. Most often it is not a breakdown of the matrix, but a software conflict or contamination of the sensor that blocks the lighting.
The main culprit behind this behavior is usually a proximity sensor, which is designed to dampen the screen when you hold the phone to your ear to avoid accidental cheekstrokes. If the sensor or its data is not properly processed by the MIUI or HyperOS shell, the phone may believe that it is already in your ear and not turn on the display. In some cases, the problem lies in the energy saving settings or conflict with the phone application.
Don't panic and take your device to the service center right away, because 90% of the time, you can solve the problem yourself in a few minutes. Below, we'll look at all the effective methods for diagnosing and troubleshooting, from simple checks to calibrating hidden system tools. It's important to understand that ignoring this error can lead to missing important calls, so you better set up as soon as possible.
Approximation Sensor: Diagnostics and Cleaning
The first thing to do is to eliminate physical contamination. The proximity sensor on Xiaomi smartphones is usually located at the top of the screen, often hidden under a thin layer of glass next to the speaker. Even the thinnest film of fat, dust, or remnants of a protective glass skewed can block the infrared radiation of the sensor. Carefully wipe the top of the display with a soft microfiber moistened in a special solution for the screens.
If physical cleaning didn't work, it's worth checking the sensor software, and the MIUI has a built-in engineering menu that allows you to test all the hardware components, and you use a special code to enter it that opens the CIT test menu, and you can see the actual state of the sensor and see if it responds to the hand.
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Use only high-quality security glass with sensor cutouts. Cheap films often block the infrared port, which makes the phone "think" that it is in your pocket.
To conduct the test, perform the following actions:
- 📞 Open the phone application (call caller).
- 🔢 Dial the combination ##6484## to enter the engineering menu.
- 🔍 Find the item "Proximity Sensor" in the list).
- ✋ Hold your hand to the top of the screen and remove it – the values should change from 5.0 to 0.0.
If values do not change or change with a delay, the problem is hardware in nature or requires calibration. In some cases, a simple reboot of the device helps, which resets temporary driver errors. However, if the sensor is “dead” even in test mode, it may be necessary to replace the plume or the module itself in the service.
Configuring the interface and permissions of the "Phone" application
Often the screen doesn't light up because the Android operating system in conjunction with MIUI aggressively restricts the background activity of applications. The system can "sleep" the application responsible for calls to save battery power, and when a call comes, it does not have time to activate the display.
Go to Settings → Apps → All apps and find the Phone app (or Google Phone if you use it). Make sure it has permission to “Map on top of other apps.” Without that right, the incoming call interface cannot physically block the lock screen or running programs.
It's also important to check the notification settings. Sometimes the call notification comes, but the screen goes out because of the "Do Not Disturb" settings or sleep mode.
- 🔔 In the settings of the "Phone" application, select "Notifications".
- ✅ Make sure the incoming call switch is active.
- 🚫 Turn off Quiet or Do Not Disturb mode for check.
Another common cause is app cache. Accumulated temporary files can cause conflicts. Clearing the cache won't delete your contacts or call history, but reset the interface display settings. Go to Memory → Clear the cache inside the properties of the Phone application.
Calibration of the sensor through the engineering menu
If the diagnostics show that the sensor is responding but not correctly (e.g., it is turning off the screen too early or not turning it on at all), calibration is required. This is a software procedure that "trains" the system to understand where the boundary between "phone at the ear" and "phone in the hand" is located. On Xiaomi, this is done through the same CIT engineering menu.
Enter the testing menu with code ##6484## and select "Proximity Sensor." You will see a screen with the current readings. Often there is a "Calibration" button or instructions to put your phone on a flat surface and close the sensor with your hand. Follow the instructions on the screen: the system will record maximum and minimum light/approximation values.
What to do if the calibration is reset?
There is also a hidden menu for calibrating sensors, available through dialing. Try entering the code ##64663## (if available on your firmware version). Here you can find more detailed sensor settings. After successful calibration, be sure to restart the device so that the changes take effect.
Resetting and system update
Software bugs in the MIUI or HyperOS shell can cause the communication modules to work in an unstable way. If the problem occurred after a recent update, there may be a bug in the new version, in which case it is worth checking for even newer security patches or, conversely, rolling back to the previous version, if possible.
If the update doesn't work, reset your network and app settings, which is a softer option than completely resetting your phone. → Connection and sharing → Resetting Wi-Fi, mobile networks and Bluetooth, which will restart all network modules, sometimes solving the problem of transmitting the screen turn on signal.
In the extreme case, when nothing works, the radical method is a complete reset (Hard Reset). Remember that this will delete all data from the phone, so make a backup in advance.
☑️ Preparation for full discharge
Once reset, the phone will return to factory status, if the problem was caused by a third-party application or an error in system files, it should disappear, and if the screen does not light up when the phone is called, the probability of hardware failure increases to 95%.
Hardware causes and repairs
When software methods are exhausted, physical damage must be considered. The screen may not light up due to the detachment of the proximity sensor plume, the oxidation of the contacts after moisture or impact. On models with a cutout (" bang") or a hole in the screen, the sensor is built directly into the matrix, and its replacement requires skilled intervention.
You should pay special attention to safety glass. Cheap glass often has an opaque frame that covers the sensor. Take off the security glass and check if the image appears when you call. Also, the cause may be the bloating of the battery, which presses on the plumes from the inside of the case, disrupting their contact.
The table below will help systematize the symptoms and possible causes:
| Symptoms. | Probable cause | Method of decision |
|---|---|---|
| The screen goes off immediately when you ring. | Contaminated sensor or defective glass | Wipe the sensor, remove the glass. |
| Black screen, but there's sound | Phone app malfunction | Clear cache, update app |
| The screen flashes or is turned on with a delay | We need calibration. | CIT's Engineering Menu |
| The problem arose after the fall. | Sensor plume waste | Disassembly and soldering/replacement |
| The data is relevant for the models of Redmi Note, Xiaomi Mi and Poco series M, F, X. |
If you don't have the skills to repair electronics, don't try to disassemble the phone yourself, especially if it's on warranty.A hull opening will void the manufacturer's warranty obligations.
Use of third-party applications for calls
Sometimes a standard Xiaomi call conflicts with a specific carrier or SIM-In these cases, a great alternative is to install the Google Dialer app from the Play Market, which completely replaces the standard interface and often works more stable.
Once you install Google Phone, you have to make it the default app, and the system will suggest you choose the default app for calling. Google's interface is more minimal and less susceptible to MIUI shell bugs associated with displaying call widgets.
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Replacing a standard call with a Google Phone solves the problem 80% of the time, unless it’s a physical sensor.
There are also specialized call management apps that can force the screen to turn on, but be careful: installing unnecessary caller apps can, on the contrary, create a new resource conflict, and it is better to limit yourself to proven solutions from Google or Microsoft.
Specifics of work in hands-free mode and headset
It's worth noting that screen behavior depends on how you take on the call. If you're using a Bluetooth headset or headphones, the screen may behave differently than when you call through a speaker. Some Xiaomi models by default don't turn on a bright screen when the headset is connected, showing only a minimalist notification to save energy.
Check your Bluetooth device settings. In some cases, you need to press the button on the headset itself to activate the phone screen. Also make sure that the Special Features settings do not include gesture controls that can block touch input or display activation.
⚠️ Warning: If the screen stopped lighting only after the phone hit the water, even if it was a couple of raindrops, turn off the device immediately. Moisture inside the case causes a short circuit, which can disable not only the sensor, but also the motherboard.
So to sum up, the black screen problem is solvable in most cases, starting with cleaning the sensor and checking the security glass, then moving on to software settings and calibration, only if these methods fail, you should consider repairing.