How to unlock the screen while talking on Xiaomi Redmi

When a Xiaomi or Redmi smartphone screen goes out during an important conversation and stops responding to touch, it's familiar to many users. It's not a software glitch as usual, but the result of a proximity sensor that mistakenly blocks the display, believing that the phone is near the ear. Often users can't complete the call or switch to speakerphone until the interlocutor puts down the phone.

The problem can be caused by both software conflict and physical obstacles, such as a safety glass or case. In most cases, you can fix the situation yourself by calibrating the sensor or changing the settings in the engineering menu. However, in rare cases, more deep intervention or even replacement of components is required if the sensor fails.

In this guide, we will take a closer look at all possible causes of screen locking and provide step-by-step instructions for eliminating them, learn how to properly adjust sensor sensitivity, disable unnecessary functions, and determine when a problem lies in the hardware of the device.

The principle of the approximation sensor on Android

The main culprit behind the lock is an infrared proximity sensor located at the top of the smartphone body, usually next to a speaker, whose task is to determine the distance between the phone and the object (your ear). When you bring the device to your face, the sensor captures the reflection of the IR beam and sends the system a command. PROXIMITY_ON, which causes the display to be turned off to save energy and prevent accidental cheek pressing.

Modern Xiaomi and Redmi models use either a virtual sensor embedded in the screen or a physical module under glass. Virtual sensors often work less consistently, responding to lighting changes or software failures of the MIUI or HyperOS shell. That is why the screen can go out even if the phone is in your hand a few centimeters away from the face.

It is important to understand that Android prioritizes (prioritizes) the signal from this sensor during an active voice call. If the sensor "sees" an obstacle, the screen will be forcibly locked, ignoring your attempts to unlock the device with a power button or swipe.

The main reasons for spontaneous blocking

Before you start to make complex adjustments, you need to rule out the trivial physical reasons. Most often, the problem lies in accessories or contamination of the top of the smartphone. Incorrectly pasted protective glass can block the area of operation of the sensor, creating a permanent illusion of proximity of the object.

• 🛡️ Protective glass or film: If the accessory is black or offset relative to the body, it covers the IR emitter.
• 🧼 Pollution: Dirt, fat, or dust in the upper speaker area blocks the sensor signal.
• 📱 Case: Some models of covers have too high sides, which interfere with the sensor when bringing the phone to the ear.
• 💻 Software conflict: Third-party applications for calls or registration topics may not properly process system signals.

Also worth mentioning is the software failures of the operating system itself, which can cause calibration settings to go down after the MIUI update, and in such cases, the screen goes out chaotically without even putting the phone to your face, and checking the sensor through the engineering menu will help you pinpoint the nature of the malfunction.

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Try to wipe the top of the screen with a microfiber with a small amount of alcohol solution, often solving the problem of false positives instantly.

Diagnostics and verification of the proximity sensor

The first step in solving the problem should be diagnostics. Xiaomi and Redmi smartphones have a powerful hardware component testing tool built in. To start diagnostics, open the Phone app and enter the secret code ##6484##. The device will automatically go to the CIT engineering menu.

In the test list, look for the Proximity sensor. When you click on it, you'll see a screen with numerical values and color indication. Normally, when nothing covers the top of the screen, the value should be close to 5.0 and the screen should be green. If you hold your palm to the top, the value will change to 0.0 and the color will turn red.

If the sensor is 0.0 (red screen), even when there's nothing in front of it, it means that the system thinks that the phone is pressed to the ear, which is the reason for the locking of the display. ↔ 0.0), but the screen still goes out, the problem may be in the software or a specific call app.

Calibration of the sensor through the engineering menu

The most effective way to fix a sensor malfunction is to calibrate it, and this process trains the system to correctly define the sensor's limits of operation, and then use the CIT engineering menu again (code ##6484##) and select Proximity sensor.

On the test screen, you'll see the Calibrate button. The process is simple: remove all objects from the top of the screen, press the button and wait until it's complete. The system will write the current position as "normal." Then you may need to close the sensor with your hand and press the button again to record the "approach" state.

Once the device is successfully calibrated, it will give you a Pass or Success message. Be sure to restart your smartphone to take effect. In some firmware versions, the calibration may not persist after rebooting, a known bug that can be solved by resetting or flashing.

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Calibration is mandatory if you have changed the display module or protective glass, without it, the sensor will not work properly.

Configure hidden parameters through engineering code

If standard calibration didn't work, you can try changing the sensor sensitivity through the engineer's hidden menu, which is a more advanced method that requires caution. Enter the code ##3646633## (not working on all MediaTek processors, but is often available on Redmi).

In the menu that opens, you can go down the path: Hardware Testing → Sensor → PS (Proximity Sensor). Here you are interested in the parameters of PS Threshold. Changing the values (usually numbers from 0 to 255 or logical levels), you can make the sensor less sensitive. However, be careful: too low sensitivity will lead to the fact that the screen will not go out at all, even in the ear, which will cause random cheek presses.

When you change settings, click Set or Apply to save settings. Check your calls. If the result doesn't work, return the original values. Remember that new versions of Android may have this menu closed by the manufacturer.

Disconnecting the sensor and alternative solutions

In situations where software methods are powerless and the screen continues to lock at the most inopportune moment, you can try to turn off the proximity sensor by software. Note: completely disabling the sensor will result in the screen never going out during a conversation, which will increase battery consumption and the risk of accidental pressing.

One way is to use third-party apps from Google Play, such as Proximity Sensor Reset/Fix or similar apps, which intercept the sensor signal and can block the command to turn off the screen. Another option is to disable the "On in your pocket" feature in the lock settings, although it affects the lock screen rather than the call itself.

It's also worth checking the settings of the Phone app itself. Some MIUI shells have a "Discourse Sensor" option inside the call settings that you can deactivate. If nothing works, you can reset the phone to factory settings, but that's a last resort.

⚠️ Note: Using third-party apps to lock the sensor may conflict with Android system processes, causing increased battery consumption or heating the device in standby mode.

Frequently Asked Questions (FAQ)

⚠️ Warning: If after all the manipulations, the sensor in the engineering menu shows constant 0.0 and does not respond to hand movements, there is a possible hardware breakdown.