Many users of the popular Redmi Note 9 Pro face an annoying problem during a conversation: the screen goes out, does not respond to touch or, conversely, the cheek resets a call. This is a classic manifestation of the incorrect operation of the proximity sensor. In Xiaomi smartphones, this sensor is located at the top of the display and is designed to save battery power by turning off the backlight when you bring the phone to the ear. However, software failures, protective films or factory defects often lead to the system mistakenly believe that the phone is in the ear, blocking the interface at the most inappropriate moment.
It is not possible to completely turn off this module with the standard settings menu, as it is part of the system call management. However, there are proven ways to bypass this problem, calibrate the sensor or force it to disable its effect on the screen through hidden engineering codes. It is important to understand that disabling the sensor will cause the screen to stop fading itself during a conversation, which can cause accidental cheekstrokes. In this article, we will discuss all available methods for solving the problem, from simple calibration to the use of third-party applications.
Before you take drastic measures, you need to rule out the physical causes of the malfunction. Often the problem is not the software, but the banal obstacles. Make sure that the security glass is flatly glued and does not overlap the area of the sensor located above the speaker. Dirt, greasy spots or a thick case can also distort the readings of the infrared emitter, causing the system to think that the object is close to the screen.
Diagnostics and check of sensor performance
The first step before any tampering with settings is accurate diagnostics, and the MIUI shell on the Xiaomi Redmi Note 9 Pro features a powerful engineering tool to test all the components of the device, and running this menu allows you to see the current readings of the sensor in real time and see if it responds to your actions at all.
To enter the test mode, open the standard Phone app and dial the combination ##6484##. If the code is entered correctly, the CIT menu will open. In the list of tests, find the "Proximity Sensor" or "Approximation Sensor" item. When you click on it, you will see a numerical value (usually 5.0 or 0.0) and a color indicator. Close the top of the screen with your palm, the value should change, and the indicator should change color. If there is no reaction, the problem may be hardware.
It is worth noting that in some versions of the firmware, access to the full engineering menu may be limited, in which case you can use an alternative way of checking through the developer’s settings or special diagnostic tools from the Play Market.
Calibration of the sensor through the engineering menu
The safest and most effective way to correct false positives is by recalibrating, often due to desynchronization of software sensitivity thresholds, a procedure that takes only a few minutes and does not require root rights or a computer connection.
Go back to the CIT engineering menu we opened earlier with code ##6484##, and select the proximity sensor test. The instruction will appear on the screen and two buttons: "Pass" and "Fail" (or "Calibrate"). Put the phone on a flat surface, making sure that there is nothing above the top of the screen. Press the calibration button. The system will automatically take the reading of the "clean" space. Then close the sensor with your palm and press the button again to lock the state "closed." If the test is successful, you will see a green inscription.
☑️ Calibration checklist
In some cases, the standard calibration may not be maintained after the reboot. Then try the extended method through a hidden menu ##64663## (If it works on your version MIUI) or go to Settings → The phone. → Version. MIUI (press 7-10 If you want to activate a developer menu, then look for debugging points. CIT.
⚠️ Attention! If the problem persists after calibration, you should not repeat the procedure dozens of times, and this may cause the calibration configuration file to fail, and then software reset will be the only solution.
Disconnection through developer settings and special commands
If the calibration didn't work, you can try to change the behavior of the system when calling. There's no direct "Switch off the sensor" button on the menu, but you can turn off the feature that uses its data to lock the screen. This is especially true for those who often use a speakerphone or headset, but the screen still goes out.
Go to Settings → Advanced Settings → For developers. Scroll down to Enter or Network. Find Quick start or Screen Start and try to change their status. While this doesn't turn off the sensor itself, it changes the logic of the accelerometer and proximity sensor in conjunction. Also, in the Developer menu, you can find the option "Don't turn off the screen" when charging, which indirectly affects the behavior of the backlight.
There is another method involved in turning off the Pocket feature. From the Settings → Screen and brightness menu, find Mode in your pocket.Switching off this feature prevents the phone from locking when it is lying in your bag, which often confuses the proximity sensor, making it think the phone is near your ear.
Secret codes for resetting sensor settings
Using third-party applications to control the sensor
When the system is exhausted, Google Play apps come to the rescue, running on top of the system and can force the sensor to ignore or correct the signals, the easiest way for users who don’t want to go deep9.
One of the most popular solutions is the Proximity Sensor Reset & Fix app, or the Fix Proximity Sensor analog, which performs a deep reboot of sensor drivers without fully restarting the phone. Once you install the app, follow the instructions: you usually need to put your phone on the table, press the Calibrate button, and wait for the process to complete.
Another approach is to use call management applications like Truecaller or specialty Dialer, which often have a setting that says, "Disable the proximity sensor" or "Ignore the call," and by installing that call and making it the default app, you can make calls without fear of the screen going out.
| Method of decision | Difficulty | Efficiency | Risks. |
|---|---|---|---|
| Removal of the protective glass | Low. | High (if the cause is glass) | Lack of screen protection |
| Calibration in the CIT menu | Medium | Tall. | Minimum |
| Third-party annexes | Low. | Medium | Advertising, access to contacts |
| Reset to factory settings | Tall. | Maximum | Loss of all data |
Radical measures: resetting and reflashing
If none of the above methods worked, the problem is probably a deep conflict of system files or damage to the configuration partition, in which case the only software solution is a complete data reset.
To perform the reset, go to Settings → About Phone → Settings Reset → Erase all data. The phone will reboot and start the cleaning process, which can take up to 10-15 minutes. Once turned on, the device will be as new, and you will need to recheck the sensor. Often this solves the problem, as all the accumulated logic errors of the Redmi Note 9 Pro are reset.
In extreme cases, even if the reset did not help, it may be necessary to flash the device through the computer using the Mi Flash Tool utility. This is a complex process that requires an unlocked bootloader and the presence of the original firmware file. Firmware errors can turn the phone into a “brick”, so this method is recommended only for advanced users.
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Before performing a complete reset, be sure to remove SIM-card and memory card to avoid accidental or file system damage during the cleanup process.
Hardware causes and physical repairs
When software methods are powerless, a physical malfunction is suspected. In the Redmi Note 9 Pro, the proximity sensor is built into the bottom speaker plume or is a separate module in the top frame. Frequent drops, moisture or simply a factory defect can cause the component to fail.
If the sensor is dead, the screen will either never go out or it will burn black all the time. In service centers, it's relatively inexpensive to replace this module, but if you have the skills to repair it, you can try to replace the plume yourself by buying the original part.
There is also a temporary “crumple” solution: seal the sensor area with opaque tape or a sticker, which will make the system think that the sensor is always closed. Then in the call settings (or through a third-party application), you need to turn on the “Always turn on the screen when you call” function, so the phone will ignore the signal “closed” because it will be permanent, and the screen will work normally, controlled only by touch.
⚠️ Attention! Slugging the sensor is a temporary solution. It deprives you of the automatic deactivation of the screen in your ear, so during a conversation, be careful not to hit the end button or the speaker button with your cheek.
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If the calibration and reset did not help, and the replacement of the protective glass did not work, there is a 90% probability that the physical sensor module in the service center will be replaced.