Owners of the popular Xiaomi Redmi Note 9 often face an intrusive notification that blocks normal use of the device, which suddenly goes off or doesn’t light up when the phone is held to the ear, and the system issues a warning to free up the top speaker area, a problem known as the “proximity sensor issue” that can turn comfortable communication into real torture, forcing users to look for ways to turn off the feature.
The reason is because the proximity sensor misinterprets the presence of a protective glass, case, or even the slightest contamination as an obstacle to the speaker. In some cases, a software failure makes the system think that the phone is in your pocket, blocking the touchscreen and screen. Understanding the nature of this failure is the first step to successfully fix it and restore full functionality to your gadget.
In this article, we will discuss all the known methods of solving this problem in detail, from simple calibration through the engineering menu to more complex manipulation of system settings, you will learn why the error occurs “don’t close the speaker area” and how to permanently get rid of false screen locks on your Redmi Note 9.
Nature of the Approximation Sensor Error
The Redmi Note series has ultrasonic or optical sensors at the top of the case. The Xiaomi Redmi Note 9 uses a virtual proximity sensor that works in conjunction with the accelerometer and gyroscope, making it sensitive to software failures. When the MIUI system receives incorrect distance data from the object, it activates the protective mechanism, blocking the screen.
A common cause is a poor-quality protective glass that overlays part of the sensor or creates glare that confuses calibration. Even a microscopic crack or a greasy trail in the upper end can be perceived by the processor as an obstacle, which is why the system insists on asking the user not to close the speaker area, although it may be physically clean.
In addition to hardware, software conflicts play a significant role. Updates to the MIUI shell sometimes change the algorithms of the sensors, which leads to desynchronization. If you recently updated the firmware and the problem arose immediately after that, it's probably a software bug that can be fixed by resetting the sensor settings.
⚠️ Warning: Using thick, black-framed protective glasses is the most common cause of false positives on the Redmi Note 9.
And you also need to consider the effects of magnetic fields and magnetic-clasp cases. Magnetic induction can affect the compass and the adjacent sensors, which indirectly affects the position of the phone in space. If you use a case-book, try to remove it and see if the error disappears.
Basic calibration through CIT's engineering menu
The most effective and safest way to fix the bug is to recalibrate the sensors through the built-in CIT (Customer Integration Test) Menu, which is available on all Xiaomi devices and allows you to diagnose and reconfigure hardware modules without obtaining superuser rights.
To enter the menu, you need to open the standard Phone app and type in a special combination of characters. Once you enter the code, the menu will open automatically. You need to find the section that checks the sensors and run the testing. The system will ask you to close and open the top of the screen with your hand, recording the readings.
☑️ Sensor calibration
When you calibrate, you need to move smoothly and clearly, and when you ask the screen to close the sensor, you need to put your palm over the top of the display (the area of the speaker), and then you can put your hand away and wait for the readings to change, and if the test is successful, the system will record the new reference values.
- 📱 Enter the code ##6484## or #4636## to enter the test menu.
- 🔍 Find Proximity Sensor (approximation sensor) in the list).
- 🖐️ Follow the instructions on the screen: Close and open the sensor in turn.
- ✅ After passing the test, press the Pass button or OK preserve results.
Once the procedure is complete, be sure to restart the device. A restart is required for the Android operating system to apply new calibration data. In most cases, about 80% of users notice the error disappearing immediately after the procedure.
💡
Proper calibration through CIT-Menu fixes problem 8 out of 10 times without needing to reset or flash.
Sensitivity setting and disabling via ADB
If standard calibration doesn't work, you can try to change the sensitivity of the sensor or turn it off software through USB debugging. This method requires connecting the smartphone to the computer and using the ADB (Android Debug Bridge) toolkit, which allows you to make changes to system files that are not available through the usual settings interface.
First, you need to activate the developer mode. → On the phone and press quickly 7-10 once under the heading “Version” MIUI". When you're a developer, a new menu will open in the "More" section, and you'll need to turn on "Debugging by" USB".
When you connect your phone to your PC, open the command line on your computer and type a command to change the sensitivity setting, which will make the sensor less susceptible to the slightest changes in light or reflections. However, beware: too much sensitivity can cause the screen to stop going out during a conversation at all.
adb shell settings put system proximity_sensor_use_debounce 0There is also a command that forces the sensor to change its logs, forcing the system to ignore certain ranges of values, a radical method that often helps Redmi Note 9 owners who have a problem with the sensor itself.
- 💻 Install the drivers. ADB Minimal ADB on your computer.
- 🔌 Connect your smartphone with a cable and allow debugging in the pop-up window.
- ⌨️ Enter the adb shell command to start the communication session.
- 🛠️ Use specific commands to reset the proximity sensor parameters.
⚠️ Note: Making changes through ADB This can cause the system to be unstable, so write down all the commands you have entered so that you can return the original values if necessary.
Comparison of methods of solving the problem
The choice of the method of solution depends on the causes of the error and your readiness for technical manipulation. Below is a table that will help you determine the most suitable way for your situation. Each method has its advantages and risks that should be considered before starting work.
| Method | Difficulty | Efficiency | Risk of data loss |
|---|---|---|---|
| Removal of the protective glass | Low. | High (if the cause is glass) | No. |
| Calibration via CIT | Low. | Medium/High | No. |
| Resetting (Hard Reset) | Medium | Tall. | Total loss of data |
| Manipulations through ADB | Tall. | Medium | Low (with care) |
As you can see from the table, you should always start with the least invasive methods. Removing the protective glass or film is the first thing you need to do if you notice a problem immediately after you stick the accessory. If the glass is transparent and good, move to software calibration.
Hard Reset is a viable method, but it takes time to restore the system and transfer files, only if other methods have failed and you are sure that the problem is not physical damage to the plume or the sensor itself.
The impact of accessories and physical cleaning
Don’t underestimate the role of physical accessories in the performance of sensors Xiaomi Redmi Note 9. Cheap protective glass often have opaque edge or adhesive layer, which eventually becomes cloudy in the area of the sensor. Even if the glass appears whole, microscopic air bubbles can distort the operation of the optical sensor.
Regular cleaning of the top of your smartphone is also an important preventive measure: Use microfiber and a little isopropyl alcohol to carefully remove fat and dirt.Do not use aggressive chemistry or abrasive materials, as they can damage the oleophobic screen covering.
How to check the quality of the protective glass?
If you use a case, make sure that its sides do not go to the front panel of the device.Some models of cases have too high edges that, when pressed in the pocket, can touch the edges of the screen and activate false alarms of the touchscreen and sensors.
- 🧼 Wash the top of the screen with a soft cloth before important calls.
- 🚫 Avoid using glass with a wide black frame.
- 📱 Check if the case is pressing on the side edges in the sensor area.
- 🔍 Inspect the speaker grid for dust and pile.
Radical measures: Resetting and reflashing
When software bugs become critical and interfere with basic functionality, you have to resort to a complete reset, which will delete all user data, applications and settings, returning the phone to a factory state. Be sure to back up important contacts and photos before you start.
To perform the reset, go to Settings → About Phone → Reset. Select “Erase All Data.” The process will take a few minutes, after which the phone will reboot as new. If the problem was caused by a conflict of system files or a third-party application, it should disappear.
In extreme cases, even if the reset doesn't work, you may need to flash the device through your computer using the Mi Flash Tool, a complex procedure that requires an unlocked bootloader and Fastboot mode skills, and allows you to replace the damaged operating system with a clean version.
⚠️ Note: Fastboot flashing requires unlocking the bootloader, which can lead to loss of warranty and data deletion.
If the firmware does not eliminate the error "do not close the speaker area", then with a high degree of probability the problem is hardware in nature, in which case the software methods are powerless, and you need to replace the sensor or plume in the service center.
💡
Before going to the service center, try tapping your finger gently on the top of the body, sometimes the contact of the sensor simply oxidizes or departs, and the mechanical action temporarily restores the connection.