Why Xiaomi Redmi smartphone does not lock the screen during a call – a full analysis of the problem

You call the phone, you bring the Xiaomi Redmi to your ear, and the screen keeps glowing, you accidentally push buttons, the conversation is interrupted. Familiar situation? This problem is common for many Xiaomi smartphone users, especially in the Redmi Note, Redmi and POCO lines. In 80% of cases, the proximity sensor is to blame, but there are other reasons, from failures in MIUI to mechanical damage.

In this article, we will discuss all the possible reasons why the screen does not lock when you call, as well as give step-by-step instructions for diagnosis and repair. You will learn how to check the proximity sensor, reset, update the firmware and even replace the sensor yourself without contacting the service center. 10/11/12, Redmi 9/10 and POCO X3/X4, where the problem is most often encountered.

Important: If your smartphone is in the water, fell from a height or was subjected to repairs, first check the integrity of the plumes and connectors, in which case software methods may not help.

1.How does screen locking work during a call

Before looking for a problem, let’s look at how Xiaomi Redmi should lock the screen in normal mode, and there are three key components:

• 📱 The proximity sensor is an infrared sensor that detects when you hold your phone to your ear, and it's located next to the front camera.
• 🤖 System software (MIUI) — processes the signal from the sensor and sends a command to lock the screen.
• 🔧 Drivers and firmware – ensure the correct operation of the sensor at the iron level.

The algorithm is simple:

1. You start the call and hold the phone to your ear.
2. The proximity sensor detects the obstacle (your ear) and sends a signal to the system.
3. MIUI locks the screen and disables touch control.
4. As soon as you pull the phone away from your ear, the sensor goes off again – the screen unlocks.

If any of these stages fail, the screen will not go out, for example, the sensor may be contaminated, the system software may not process signals correctly, and the firmware may contain errors.

2. The proximity sensor is the main cause of the problem

In 90 percent of cases, the proximity sensor is the one to blame, and it can fail for a number of reasons:

• 🧴 Pollution – dust, grease, or moisture enters the sensor area (especially if you carry your phone in your pocket without a cover).
• 💥 Mechanical damage – impact, fall or pressure on the top of the screen.
• 🔌 Contact oxidation – if the phone has come into contact with moisture (even condensate).
• ⚡ Calibration failure – the sensor is working but does not correctly determine the distance.

How to check the proximity sensor on Xiaomi Redmi:

1. Open the Phone app and type ##6484## (some models run ##0*# or #4636##).

If the values don't change, or if the sensor shows N/A, it's malfunctioning. If the values change, but the screen doesn't lock anyway, the problem is the software part.

⚠️ Note: On Redmi Note models 11 Newer test codes may not work due to limitations MIUI 13/14. In this case, use third-party apps like Sensor Test from Google Play.

3. Software failures: MIUI, firmware, applications

If the proximity sensor is in good shape, but the screen is not locked, the software is to blame.

The fastest way to check the software part is to go into safe mode:

1. Press the power button before the off menu appears.
2. Press and hold the item Turn off.
3. Confirm the transition to safe mode.
4. Call someone and check the screen lock.

If the screen locks normally in safe mode, the problem is in one of the installed applications, and if not, the firmware or system settings are to blame.

💡

Before resetting, save your data via Settings → About Phone → Backup. This will allow you to quickly restore contacts, SMS and settings after reset.

4. MIUI settings that interfere with screen locking

Sometimes the problem lies in the incorrect settings MIUI. Here are the parameters worth checking:

• 🔍 Permissions for the phone app: Go to Settings → Annexes → Application management → Phone. → Permits and make sure all permissions are included.
• 📱 Gestures and buttons: In Settings → Screen. → Disable the option to raise to wake up – it may conflict with the proximity sensor.
• 🔄 Adaptive brightness: In Settings → Screen. → Brightness turn off adaptive brightness – sometimes it interferes with the correct operation of sensors.
• 🛠️ Developer Mode: If you have enabled Debugging by USB Or other options for developers, they can affect the sensors. Turn them off in Settings. → The phone. → Version. MIUI (7 times click on the version, then go to the Developer Settings).

Also check the settings of special features:

1. Go to Settings → Special Opportunities → Physical Opportunities.
2. Make sure the Auto Rotation option is on (sometimes it affects sensors).
3. Turn off the Conversation Retention if it is active.

If you use third-party launchers (Nova, Apex, POCO Launcher), try returning the standard MIUI launcher.

5. Mechanical damage: plumes, connectors, screen

If the software methods didn't work, the problem could be the hardware, and most often, the problem is:

• 🔌 Approximation sensor plume – moved away or damaged after falling.
• 📱 Display module – if the phone fell or was subjected to pressure, the flexible plume connecting the screen to the motherboard could be damaged.
• 💧 Contact oxidation – if the phone has come into contact with moisture (even steam in the bathroom).
• 🔧 Microphone module – on some Redmi models, the proximity sensor is integrated into the microphone unit.

How to check the hardware:

1. Carefully examine the phone for cracks, dents or traces of moisture.
2. Try to press slightly on the top of the screen (where the sensor is located), and if the screen starts to lock, the problem is poor plume contact.
3. Connect your phone to your computer and check if the sensor is detected in Device Manager (on Windows) or through adb devices.

⚠️ Note: If you don't have experience in disassembling phones, don't try to check the plumes yourself. Redmi Note 10 Pro and newer models use glue. B7000, It requires careful heating to remove the screen, and the wrong actions can cause the display to fail completely.

6. Update firmware and reset settings

If the sensor is working and the settings are not working, try updating or reinstalling the firmware, which will solve the problem in 60% of software failures.

Method 1: Update via OTA

1. Go to Settings → About the phone → System update.
2. Click Check Updates and install the latest version of MIUI.
3. After the update, reboot.

Method 2: Manual updates through Recovery

1. Download the official firmware for your model from the Xiaomi Firmware website.
2. Rename the file to update.zip and place it in the root of the phone’s memory.
3. Press Volume Up + Power to enter Recovery.
4. Select Install update.zip and confirm the installation.

Method 3: Complete reset (Hard Reset)

If the update does not help, reset to factory settings:

1. Create a backup copy of the data.
2. Go to Settings → About Phone → Backup and Reset.
3. Select Reset and confirm the action.

⚠️ Note: On models with a blocked bootloader (for example, Redmi Note 12 for the Russian market), a reset via Fastboot can result in the blocking of the Mi Account.

💡

If you've had a problem after the reset, it's iron, and 95 percent of the time, it's either a proximity sensor or a display plume.

Alternative solutions and interim measures

If you need to use your phone urgently and repairs are delayed, use temporary solutions:

• 📱 Manual lock: During the call, press the Power button to lock the screen manually.
• 🔕 Headset usage: Connect wired or wireless headphones – the screen will lock automatically.
• 🛠️ Third-party apps: Install Proximity Sensor Fix or Sensor Disabler from Google Play. They force the screen to lock during a call.
• 📲 Airplane Mode: If the problem is network conflict, turn on Flight Mode before calling.

For the POCO X3/X4, there is a patch from the XDA Developers community that fixes the proximity sensor, which can be installed via Magisk (root rights required).

If you decide to use third-party applications, pay attention to:

• Proximity Sensor Reset – Resets the sensor calibration.
• Sensor Test – Checks the operation of all sensors.
• Automatic Call Recorder – Some versions have a built-in screen lock.

FAQ: Frequent screen lock questions on Xiaomi Redmi