Xiaomi Redmi 9 smartphones have proven to be reliable devices with excellent value for money, but users often face intrusive sensors. One of the most common complaints of owners is spontaneous screen suppression during phone conversations or when listening to audio messages in messengers. This is due to the high sensitivity of the proximity sensor, which responds to even minimal shifting of the phone at the ear or accidental touching of the cheek.
Things get particularly annoying when the screen goes out at the most inopportune moment, preventing you from pressing the speaker button or completing a call. Fortunately, the MIUI operating system that powers Xiaomi phones provides enhanced hardware fine-tuning capabilities. Unlike many other manufacturers, you can not only calibrate the sensor, but also completely deactivate it with software methods without obtaining superuser rights.
In this guide, we will take a look at all the solutions available, how to get into the hidden engineering menu, what options to change and what to do if standard methods do not work. It is important to understand that disabling this module will change the logic of the phone when you make calls, so before making changes, it is worth weighing the pros and cons.
The reasons for false alarms on the Redmi 9
Before we go to radical measures and turn off the functionality, we need to understand the nature of the problem. The approach sensor on Redmi 9 is an infrared emitter and receiver located at the top of the display, and its task is to determine the distance to the object and turn off the backlight of the screen when the phone is brought to the face to avoid accidental cheek pressing.
However, in reality, users often face a situation where the screen goes out, although the phone is in the dark. 10-15 The main culprits of this behavior are often protective glass or film that covers the sensitive element, and even a microscopic scratch or layer of fat can distort the sensor readings, making the system think that the device is pressed against the ear.
In addition to physical obstacles, there are software failures. Updating the Android operating system or the MIUI shell sometimes leads to incorrect calibration of the default values, in which case the sensitivity threshold is knocked down, and the phone responds to the slightest changes in light in the upper end of the case.
- 📱 Protective glass: Incorrectly pasted film or glass with a black frame often overlaps the sensor, causing false positives.
- 🧼 Pollution: Dirt, dust, or greasy traces in the area of the speaker block infrared radiation.
- ⚙️ Calibration failure: Software failure after system update leads to incorrect reading of distance to object.
⚠️ Warning: Before turning off the sensor, make sure the problem isn't solved by simply cleaning the top of the screen.Using alcohol wipes can help remove the fat plaque that is often the cause of failures.
Preparing the smartphone to change system settings
The process of disabling the proximity sensor on Xiaomi Redmi 9 requires access to hidden system functions. This does not require installing third-party applications or obtaining root rights, but you need to be careful when entering commands. Any careless action in the engineering menu can lead to unstable operation of other modules of the phone.
The first step is to ensure a stable battery charge. Although the setup process does not require much power, suddenly turning off the phone while working with system settings is highly undesirable, and it is also recommended to disable any third-party launchers or applications that control calls so that they do not conflict with system settings.
It's important to understand that once the sensor is turned off, the screen will stop turning off automatically, which means that during a conversation, you'll have to manually lock the screen with a power button if you don't want to accidentally tap your cheek, which is a fundamental change in the logic of the device, which you need to be prepared for.
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Before making any changes to the engineering menu, take a screenshot of the current parameters values, which will allow you to quickly return all settings back if something goes wrong.
Make sure your device has USB debugging enabled, although it is not always required to log in to the engineering menu through code, but if the standard codes do not work, the presence of the developer mode enabled may be required to use alternative computer calibration methods.
Entrance to the engineering menu through USSD-code
The fastest and most efficient way to access sensor control on Redmi 9 is to use a special engineering code built into the phone’s firmware and doesn’t require an internet connection or additional software, and the code is universal for most MediaTek-based devices that are used in this model.
To start, open the standard Phone app, which you usually make calls through. In the dial box, you need to enter a special combination of characters. On Xiaomi devices, the most common code is ##6484## or ##4636##. In the case of Redmi 9 and the MIUI shell, the first code that opens the CIT menu (Customer Integration Test).
Once you enter the last star, the menu should open automatically. If it doesn't, check if the code is entered correctly and make sure that it is not. SIM-In some regions, operators can block the input of certain characters, then you will need to use alternative methods through the developer settings.
☑️ Check before entering the engineering menu
The interface of the engineering menu is a list of tests of the various components of the device. We're interested in the section related to the Proximity Sensor. Navigation is done by simply touching the screen. If the list is too long, you can use scroll. It's important not to press the Start button in tests unnecessarily, unless you're planning to calibrate, but only want to change the settings.
Disabling the sensor through hidden MIUI settings
Newer versions of the MIUI shell on Redmi 9 have a feature that allows you to control the sensitivity of the proximity sensor without logging into the deep engineering menu, which is the safest way for ordinary users, since it eliminates the risk of changing critical system parameters.
To access this feature, you need to go to the standard Phone app, which is system-based and cannot be removed. In the upper right corner of the screen is a menu represented by three dots or a gear icon. When you click on it, you will see "Call settings" or "Settings", depending on the version of the interface translation.
In the settings that open, you need to find the "Proximation Sensor" section, and that's where the switch that regulates the sensor is hidden, and in some firmware versions, this item may be called "Cast-Blocking" or have a similar name, which is related to preventing errors during a call.
⚠️ Note: If you did not find the “approximation sensor” item in the call settings, then your version MIUI In this case, you need to use the engineering code method or third-party applications to emulate the shutdown.
Once you find the right switch, just turn it off. The system can request confirmation of the action, warning that the screen will no longer go out automatically. Accept the warning to make the changes effective. Check the result by making a test call.
Using the Phone app to disable the function
An alternative and often more effective way is to use the settings of the Phone app itself from Google or the MIUI Dialer system app. Depending on the region, one of two calling apps can be installed on Redmi 9, and the settings may differ.
If you have a standard Google Dialer installed, the algorithm is this: Open the app, go to settings through a three-dot menu, find the Incoming Calls section, which is where the Approximation Sensor option often hides, and disabling it solves the problem 90 percent of the time on global firmware versions.
If you use Xiaomi’s native app (orange or green handset with the MIUI logo), the path may be different. The settings are often hidden deeper. Sometimes you need to activate the hidden developer menu inside the call app itself. You need to click several times on the version number of the app in the About Phone section in the app settings.
| Type of application | The path to adjustment | Option name | Status of work |
|---|---|---|---|
| Google Dialer | Settings -> Incoming calls | Approximation sensor | It's stable. |
| MIUI Dialer (CN) | Settings -> Additional | Touch-blocking | Requires a check-up. |
| MIUI Dialer (Global) | Settings -> General | Approximation sensor | Often hidden |
| Third-party (Truecaller) | Settings -> Calls | Screen during the call | Depends on the version. |
After making changes to the app settings, the phone may need to restart. Don't ignore this request, as the background call management processes are only updated after the full cycle of the device on and off, ensuring that the new settings are applied correctly.
Sensor calibration as an alternative to shutdown
Before you finally give up the useful random-press protection feature, it's worth trying to calibrate the sensor. Often the problem lies not in the function itself, but in the wrong base values that the controller reads. Calibration allows you to "train" the phone to understand what "close" is and what "far" is in your particular conditions.
To do the calibration, go back to the engineering menu we opened earlier with code ##6484##. In the test list, look for the Proximity Sensor. Click on it to open the test window. You'll see two values: current distance and status (Near/Far).
Close the sensor with your hand (the value should change to Near), then remove your hand (the value should become Far). If there is a reaction but it is late, press the Calibration button in the bottom menu. Follow the instructions on the screen: close the sensor when you ask, and remove the hand when you need. Once successful, a success message will appear.
What to do if the calibration does not pass?
Once you've calibrated successfully, be sure to restart the device, which will reset the cache of old values and force the system to use new thresholds of sensitivity, and in most cases, this solves the problem of false positives better than completely shutting down the function.
Solving problems with the fading screen in messengers
Special attention should be paid to the situation when the screen goes off not during normal calls, but when listening to voice messages on WhatsApp, Telegram or Viber. The mechanism is the same, but the settings can be duplicated within the applications themselves. Often users turn off the sensor in the system, but forget to check the settings of the messenger.
On WhatsApp, you have to go to the app's settings, select the Chats section, and find the "Approach Sensor" option, and if it's active, when you bring your phone to your ear while you play a message, the screen will go out, and turning that option off inside the app is more important than the system settings for that particular case.
In Telegram, the situation is similar: Settings -> Chats and channels -> Disable the proximity sensor. It is important to note that in some versions of MIUI there is a conflict between the system control of the sensor and requests from messengers. If the messenger is not available and the screen goes out, only the system shutdown through the engineering menu will help.
- 📱 WhatsApp: Settings -> chat -> Proximation sensor (off).
- ✈️ Telegram: Settings -> Chats and channels -> Disable the proximity sensor (set the switch on).
- 💬 Viber: Settings -> Challenges -> Proximation sensor (off).
It’s worth remembering that using third-party apps to control sensors from the Play Market often doesn’t give the desired result on Xiaomi. MIUI It strictly controls access to hardware sensors, and third-party software simply does not have sufficient rights to override system parameters.
⚠️ Attention: After turning off the proximity sensor, be careful when talking.The screen will burn constantly and you may accidentally press the call end, hands-free or dial button with your cheek.Exercise accuracy or use a headset.
Frequently Asked Questions (FAQ)
Is it safe to turn off the proximity sensor on Redmi 9?
Why did the sensor settings disappear after the MIUI update?
Does the protective glass affect the sensor after the shutdown?
Can the sensor be turned off for a specific application only?
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Turning off the proximity sensor completely is a last resort, and 80 percent of the time, the solution is to calibrate correctly through an engineering menu or replace a poor-quality protective glass.
To sum up, the proximity sensor on the Xiaomi Redmi 9 is in the hands of the user, whether it's a simple menu setup, deep calibration or complete shutdown, you have complete control over the behavior of your device, and the main thing is to act consistently and check the result after each change.