How to turn on screen lock when talking on Xiaomi Redmi Note

Many Xiaomi smartphone owners face the annoying problem of having their screen glow instead of go out during a phone call, which not only interferes with comfort, but also leads to occasional cheek presses, which can interrupt the call or turn on speakerphone. Owners of Redmi Note series models often wonder how to force this feature to activate if it does not work automatically.

In fact, there is no separate button to “enable lock” in a MIUI or HyperOS system, since this process must occur automatically due to the operation of hardware sensors. If the screen does not go out, then the system does not receive the correct signal from the proximity sensor. In this article, we will discuss in detail the mechanics of this function, how the software is set up and methods for physical cleaning of the sensor that will help return the smartphone to normal behavior.

Understanding the way automatic locking works is the first step to solving the problem. A smartphone uses an infrared sensor located at the top of the body, usually next to a speaker or in a cutout under the front camera. When you hold the device to your ear, this sensor detects the change in distance and sends a signal to the operating system to turn off the display.

Importantly, it's not just hardware that does this, it's also software that does this. There's a system service in the MIUI shell that handles sensor data, and if it's malfunctioning, or if there's a protective film on the screen that overlays the sensor, the screen will stay on even when the phone is pressed tightly to the head.

Sometimes users mistakenly believe that the feature needs to be activated manually in call settings. However, in modern versions of Android and Xiaomi's proprietary shells, this option is basic and turned on by default. The lack of screen response often indicates the need to calibrate or remove a physical obstacle, rather than finding a hidden switch.

The mechanism of the proximity sensor in MIUI

The technology used in Xiaomi Redmi Note smartphones is based on infrared light emission and analysis of its reflection. When an object (your ear) is close, the reflected signal returns to the receiver at a certain intensity, the system interprets this data and blocks the touchscreen to prevent false positives.

In the software part, this is the Proximity Sensor process, which takes precedence over other user actions during an active call. If you notice that the screen goes out, but immediately lights up again, or does not respond at all, this may indicate a desynchronization of software sensitivity thresholds.

⚠️ Warning: Using non-original black-framed protective glasses that enter the speaker area is the most common cause of sensor failure.Infrared radiation simply cannot make its way through the opaque layer.

It is also worth considering that in some Redmi models, the sensor can be software (virtual), using accelerometer and gyroscope data if the physical sensor is missing or damaged, but in most cases it is a physical IR module that requires direct access to the external environment.

Checking the settings of the phone and application

Before you go to complex engineering tests, you need to make sure that the basic settings of the system were not changed accidentally, and in some cases, updates to the operating system can reset parameters or make changes to the logic of the interface.

First, check the settings of the Phone app itself. Depending on the version of the MIUI shell, the path may vary slightly, but the overall logic remains the same. You need to find the section responsible for incoming calls and screen behavior during a conversation.

• 📱 Open the Phone app and tap on the three dots or gear icon in the corner of the screen.
• 🔍 Go to Settings or Additional Settings section.
• ✅ Find the Approximation Sensor and make sure the switch is activated.
• 🔄 If the item is already on, try turning it off, restarting the device and turning it on again.

It's also worth checking if you have a third-party launcher or call app installed that may conflict with Xiaomi's system services.The standard MIUI Dialer or Google Dialer app (depending on the region) have the highest priority and the fewest compatibility errors.

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If you've recently installed a third-party theme, try returning a standard theme. Custom themes often contain code errors that block system sensors.

Calibration of the sensor through the engineering menu

If simple adjustments didn’t help, the most effective way to solve the problem is to calibrate the sensor. Xiaomi smartphones have a hidden engineering menu that allows you to test and customize various modules of the device, including the proximity sensor.

To enter the test mode, a special code is used, which you need to enter into the dialing field, which is safe if you follow the instructions, and allows you to reset the software calibration errors that have accumulated over the course of operation.

1. Open the Phone app and go to dialing.
2. Enter the combination ##6484## to log into the Engineering Menu (CIT).
3. In the list of tests, find the Proximity Sensor item (usually it is at the beginning or middle of the list).
4. Follow the instructions on the screen: Cover the top of the phone with your hand, then remove it.
5. Press the Pass or Calibrate button to save the new values.

Once the calibration is successful, the system will re-write the trigger thresholds, which is especially useful if the sensor has forgotten when the phone is in the ear and when it is in the hand. In some firmware, the code may differ, such as ##4636##, but the CIT option is the most complete one for Redmi.

Physical Causes and Maintenance of the Device

Physical factors are also not to be discounted: Redmi Notes are often used in active environments where they are exposed to dust, moisture or dirt, and microscopic layers of fat from fingers or dust in the area of the speaker can block the IR ray.

Carefully wipe the top of the screen with a soft microfiber slightly soaked in alcohol solution (do not allow moisture to enter the holes). Pay special attention to the area above the display. If you carry the phone in your pocket without a case, the pile of fabric can also clog the sensor.

The table below shows the main physical causes of malfunction and ways to eliminate them:

If you use a case with high sides, make sure it doesn't overlap the top of the device. Even minimal overhang of plastic can create a permanent shadow for the sensor, and the system will think that the phone is pressed against the ear all the time, or, conversely, ignore the approach due to a distorted signal.

Program conflicts and system updates

Sometimes the problem isn't with the sensor itself, but with the operating system, and errors in MIUI code can cause the service that locks the screen to freeze or not start, often after major updates or when installing beta versions of firmware.

Check for available system updates. Xiaomi developers regularly release patches that fix known bugs. Go to Settings → About Phone → MIUI version and click the update check button.

⚠️ Note: If the problem occurred immediately after the system update, there may be a critical error in the new version, in which case you should wait for the next patch or roll back to the previous version of the firmware via Recovery.

It’s also worth checking which apps have access to the phone and sensors. Some battery optimizers or antiviruses can block background processes necessary for the proximity sensor to function properly. Try running the phone in safe mode to eliminate the impact of third-party software.

Resetting and extreme measures

If neither calibration, nor cleaning, nor updates helped, the last software method is a complete reset. Hard Reset will return the phone to factory status by removing all user data and configurations that may have caused the conflict.

Before performing this procedure, be sure to back up all important data, as it will be permanently deleted. Reset can be done through the settings menu or using a combination of buttons on the device that is turned off.

The sequence of actions through the menu:

Settings → About the phone → Reset settings → Erase all data

Once reset, the phone will look like new. Don't install all the apps at once. First, check the call on a clean system. If the screen doesn't go out, the probability of hardware failure (a plume break, a sensor failure) is more than 90%.

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If after a complete reset and flashing sensor does not work, the problem is hardware in nature and requires a replacement of the module in the service center.

Frequently Asked Questions (FAQ)