Why the screen turns off when calling Xiaomi: reasons and solution

The situation when during an important conversation suddenly goes out the display of a Xiaomi smartphone, familiar to many users, it is not just an annoying bug, but often the result of a regular security system designed to protect you from accidental brushing of the cheek, but when the screen stops responding to attempts to turn it back on or goes out too early, it turns communication into torture.

At the heart of this process is a proximity sensor, a miniature sensor that sits at the top of the body, and its job is to capture the distance to the object (your face) and lock the touchscreen so that you don't accidentally drop the call or turn on the speakerphone with your ear, but like any mechanism, this feature is prone to software failures and physical interference.

Next, we’ll take a closer look at why Xiaomi behaves this way, what MIUI settings might conflict with the sensor, and how to fix the situation if the screen doesn’t light up after the phone is removed from the ear, how to calibrate the sensor manually and why a cheap protective glass can cause a problem.

The principle of the sensor approach in smartphones Xiaomi

The technology behind the locking is based on infrared radiation, the sensor emits an invisible beam and reads its reflection from nearby objects. If the reflected signal returns quickly, the system recognizes that the phone is in the ear, and activates the energy saving mode along with the touchscreen locking. On current models of Redmi and POCO, this process takes fractions of a second.

It's important to understand that the sensor doesn't work in a vacuum, and it's affected by external factors, such as the brightness of the ambient light, the presence of thick side covers, and even pollution. Android software interprets the sensor data and tells the display to go out. If the calibration is knocked down, the distance threshold can be violated.

⚠️ Attention: Attempting to physically repair or disassemble the top of the smartphone to clean the sensor can lead to a leakproof housing and loss of warranty.

There are two main types of sensors used in Xiaomi’s lineup: classic physical sensors and virtual sensors based on AI algorithms. Physical sensors are more reliable but prone to contamination. Virtual sensors implemented in recent firmware versions analyze user behavior, but can be mistaken when a device is not standard grip.

The main reasons for spontaneous screen suppression

The first and most obvious reason is a physical barrier, and even a microscopic layer of fat, dust, or pile from your pocket that hits the speaker area can distort the infrared light, and in this case, the phone thinks it's still in your ear, even when you've removed it from your arm's length.

The second reason is often software conflicts: After updating MIUI or installing third-party applications to manage calls, system services can be bugged, especially for devices that have rooted or unlocked the bootloader.

• 📱 Poor quality protective glass: Cheap films often have an opaque frame or thickness that overlaps the sensor.
• 🧼 Top panel contamination: accumulation of skin fat and dirt in the area of the conversational speaker.
• 🔄 Firmware errors: bugs in the HyperOS shell or older versions MIUI, patchy.

Also worth mentioning is the problem of overheating, where if the smartphone is in talk mode, especially in hot weather or in the sun, the sensor may start to give out incorrect data due to changes in the temperature of the crystal, in which case the system may force the screen to turn off to reduce the load.

Diagnostics and check of sensor serviceability

Before we go to radical measures, we need to determine whether the problem is hardware or software. Xiaomi smartphones have built-in engineering menus that allow you to check all the components of the device without installing third-party software, this is the most reliable way to initial diagnosis.

To enter the test mode, you need to dial a special code in the Phone application. After entering the combination, the CIT menu will open, where you can test each module separately, and we are interested in the item associated with the Proximity Sensor.

##6484##

In the list that opens, look for the "Proximity sensor." Close the top of the screen with your hand and remove it. If the values change from 5.0 (or Close) to 0.0 (or Far), then the hardware is good, and the problem lies in the settings or the software. If the reaction does not occur even with active waving of the hand, it may be physically defective or disabled in the system.

Calibration of the proximity sensor: step-by-step instructions

If the sensor is responding but not working properly (extinguishing the screen too early or not turning it back on), calibration is required, which "trains" the system to understand where the boundary between "phone in the ear" and "phone in the hand" is.

To perform the calibration, go back to the engineering menu with code ##6484## and select "Proximity sensor." Put your phone on a flat surface, making sure there's nothing above the top edge. Press the "Calibration" button.

Once the process is completed successfully (it will be labeled "Pass" or "Success"), you need to restart the device. In some versions of MIUI, calibration can be done automatically every time you turn on the phone, if you have previously reset the sensor settings through the developer menu.

⚠️ Attention: During calibration, you should not touch the top of the screen or create vibrations. This will confuse the readings and make the calibration incorrect.

Influence of protective glasses and accessories

One of the most common reasons why the screen goes out and doesn't light up is because of the wrong security glass. Many users, wanting to protect the Xiaomi display, buy glass with a black frame around the perimeter, which can overlap not only the front camera, but also the light / proximity sensor.

Even if the glass is transparent, its thickness can be critical. Infrared beam has a certain angle of scattering, and thick glass (more than 0.3 mm) can create a "tunnel effect", which makes the sensor go blind.

In addition to the glass, magnetic cases with Smart Cover function can cause problems. If the magnetic fastener is too close to the upper end, it can interfere with the Hall sensor or the proximity sensor itself, making the phone think that the case is closed.

Software settings and reset configuration

If (hardware) is fine and calibration is not helpful, you should consult software settings. Some versions of the MIUI shell have a feature called "Remove rattles" or "Anti-flashing" that can aggressively block the screen, and it is also worth checking the permissions for the "Phone" application.

Try clearing the Phone and Contacts cache. Go to Settings → Apps → All apps, find a standard call set, and click Clear. This won't delete your contacts, but reset your call processing settings.

In extreme cases, if nothing works, you can try to turn off the proximity sensor software, and there are special applications from Google Play, such as "Proximity Sensor Reset/Fix," which allow you to force the screen to be turned on during a conversation, handing control of the lock to the volume buttons.

FAQ: Frequently Asked Questions

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Use Voice Control in your call settings, which will allow you to receive and terminate calls with voice commands, reducing the need to touch the screen and reducing the risk of accidental locking.

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In 90% of cases, the problem is solved by simply cleaning the top of the smartphone from fat and dust or replacing poor-quality protective glass with a thinner one.

To sum up, screen suppression on Xiaomi is often a security mechanism that just requires correction. Start with device hygiene and security accessories before you go into deep system settings. Proper calibration and understanding of the sensor will allow you to forget about this problem and enjoy comfortable conversations.