How to lock the screen on Xiaomi Redmi 9 during a conversation: all the ways

Accidental tapping of the screen during a phone conversation is a common problem of users Xiaomi Redmi 9. the application “Phone” in MIUI does not always correctly lock the sensor when holding the smartphone to the ear, which can inadvertently end the call, enable speakerphone or activate other functions, especially for owners of devices with large displays, where the risk of touch increases.

In this article, we’ll look at all the working ways to lock your screen on Redmi 9 while you’re calling, from standard MIUI features to hidden settings and third-party apps, how to set up automatic proximity sensor lock, use gestures or physical buttons, and what to do if the sensor stops responding to touch, and instructions are suitable for all firmware versions, including MIUI 12/13/14.

Why the screen doesn’t automatically lock when you call

On the Xiaomi Redmi 9, the proximity sensor, a small sensor next to the front camera, detects when you hold your phone to your ear and turns off the touch screen. If the lock doesn't work, the reasons may be as follows:

• 🔹 Sensor contamination: dust, protective glass or film block the signal.
• 🔹 Firmware damage: failure after update MIUI or.
• 🔹 Disabled function in phone settings (for example, after resetting to factory settings).
• 🔹 Application conflict: Some programs (such as launchers or optimizers) may block the sensor from working.

Before you configure alternative locking methods, check the sensor.

1. Open the Phone app and dial ##6484## (sensor test).
2. Cover the area next to the front camera with your hand – the screen should go out.
3. If there is no reaction, clean the sensor with a soft cloth or reset the settings of the Phone application in Settings → Apps → Application Management → Phone → Storage → Clear the data.

Method 1: Power button lock (most reliable method)

The most versatile and all versions of MIUI are manual power button locks, which are independent of sensors or firmware settings, so they are suitable even if the proximity sensor is broken.

How it works:

1. During the call, briefly press the power button (located on the right end of Redmi 9).
2. The screen will go out, but the call will continue - the sensor will be locked until the next press.
3. To unlock, press the power button again and swipe your finger across the screen (if the pattern lock or PIN is configured).

⚠️ Warning: If you have Double-click to wake up (Settings) → Screen. → Double tap to wake up, casual touch of the screen can unlock your phone. Turn it off if you plan to lock the screen frequently with a button.

Check that the power button does not stick and works clearly |

Turn off double tap to wake up |

Make sure the button is not pressed by the case|

Set up a lock without a lock. PIN-code (if you need to quickly unlock)-->

Method 2: Configure the proximity sensor in MIUI

If the proximity sensor is working but the lock is delayed or unstable, it can be reconfigured via hidden MIUI menus.This method requires care, as improper changes can lead to failures.

Instructions:

1. Open the Phone app and enter the code: ##6484## The sensor testing menu will open.
2. Find the Proximity Sensor and click on it.
3. Cover the sensor with your hand, the value should change from 5.00 to 0.00. If there is no reaction, the sensor is defective.
4. To calibrate, enter the code ##2664## and follow the instructions on the screen.

If the sensor is working, but the lock does not work, check the settings:

• 📱 Go to Settings. → Annexes → Application management → Phone. → Permits.
• 🔧 Make sure the app has access to sensors and phone.
• 🔄 Reboot your phone after the changes.

Method 3: Using gestures to lock the screen

MIUI 12 and later introduced a gesture feature to lock the screen, which allows you to lock the smartphone with a double touch on the screen without pressing the power button, which is useful if the physical button broke or it is not convenient to reach it during a call.

How to turn on:

1. Go to Settings → Screen → Screen Lock and Password.
2. Find the option Double-Tap to lock (or Lock Gestures in newer versions of MIUI).
3. Activate the switch and confirm the action.

Now, when you call, you just need to touch the screen twice (not by icons!) to block it. To unlock, use the power button or double tap (if enabled).

⚠️ Note: Double-touch gestures may interfere with the functions of certain applications (e.g. games or instant messengers).If the locking is triggered accidentally, disable this option.

Method 4: Third-party applications for forced blocking

If standard methods don’t work, you can use specialized apps from Google Play that offer advanced features, such as:

• 🔒 Locking the screen by timer (for example, 5 seconds after the start of the call).
• 📱 Automatically shutting down the sensor when holding the phone to the ear (alternative to the proximity sensor).
• 🔧 Set up exceptions for certain contacts.

The best apps for Xiaomi Redmi 9:

1. Proximity Service -- emulates the proximity sensor if it breaks, requires ADB rights to work properly.
2. Gravity Screen – locks the screen when you change your phone’s position (for example, when you put it on the table).
3. Call Lock is a specialized application for locking the screen during calls with customizable gestures.

⚠️ Note: Screen locking applications require permission Special features (Settings) → Special facilities → Special features services: Do not install programs from unverified sources, they may collect call data.

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Before installing a third-party app, check the user reviews of Xiaomi Redmi 9 – some programs may not work correctly on devices with MIUI.

Method 5: Blocking through the settings of the Phone application

Recent versions of MIUI have introduced hidden phone settings that force the screen to lock during a call, which are not always visible in the main menu, but can be activated through the developer settings or the engineering menu.

Step-by-step:

1. Activate Developer Mode: Go to Settings → About Phone. 7 times click on MIUI Version. Return to Settings → Additional → For Developers.

USB debugging

Phone.

##4636##

Usage statistics → Phone information

Proximity sensor calibration

Phone.

Locking the screen during the call

After calibrating the sensor through the engineering menu, the screen lock during the call should be triggered instantly - without the delays characteristic of standard firmware.

What to do if nothing helps: hardware solutions

If the software methods do not work, the problem may lie in the hardware of the Xiaomi Redmi 9.

• 🛠️ Approximation Sensor: Check it for damage. If it moves away from the board or is covered with glue (a common problem after screen repairs), the lock will not work.
• 🔌 Screen plume: When the phone falls or breaks down, the plume may have been damaged, which causes the sensor and sensors to malfunction.
• 🔋 Firmware: If the problem has occurred after the update MIUI, Try to roll back to the previous version or install custom firmware (e.g. Pixel Experience).

For the diagnosis of hardware malfunctions:

1. Connect your phone to your PC and check the sensor logs via ADB: adb shell dumpsys sensorservice In the output, find the proximity bar – if the values do not change when the sensor is closed, it is faulty.
2. Try to temporarily turn off the security glass – sometimes it blocks the signal.
3. If the phone falls, check the integrity of the screen plume (disassembly is required).

⚠️ Attention: Self-repair of the proximity sensor or the screen plume without experience can lead to a breakdown of the Redmi 9. If you are not sure of your abilities, contact the service center. The cost of replacing the sensor is from 500 rubles, the plume - from 1500 rubles.

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If the locking of the screen stopped working after the screen was replaced, in 90% of cases, a faulty plume or an incorrectly connected proximity sensor is to blame.

FAQ: Frequent questions about screen locking on Xiaomi Redmi 9