Modern smartphones are complex devices where each element plays a critical role in comfort. The proximity sensor on the Xiaomi Redmi Note 9s is just such a component that often goes unnoticed until it stops functioning correctly. Understanding its location and how it works allows owners to effectively solve screen problems during conversations.
The location of this sensor is not always obvious, as manufacturers tend to hide it under the display to preserve the aesthetics of the device. In the Redmi Note 9s, engineers have applied a certain configuration that requires careful study when diagnosing malfunctions.
In this article, we will go into detail the anatomy of the top of the smartphone, the methods of software verification and how to fix common failures. Infrared sensor is not just a detail, but a guarantee that your phone will not dial the number with your cheek during an important call.
Physical location and sensor design
On the Xiaomi Redmi Note 9s, the proximity sensor is physically integrated into the top of the display module. Unlike older models, where it could be carried into a separate hole, it uses hidden placement technology under the screen.
So structurally, it's a small infrared emitter and receiver that work in pairs, and when you hold the phone to your ear, the infrared beam bounces off the surface and returns to the receiver, signaling the system to turn off the touchscreen. On the Redmi Note 9s, this area is located right in the center or slightly offset, depending on the specific revision of the board.
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When sticking a protective glass, make sure it has a special cutout or a transparent area at the top, otherwise the sensor may not work properly.
It's important to understand that there may not be any visible holes on the front panel at all, that the sensor module is hidden behind a layer of glass, and it works by transmitting infrared spectrum, and any contamination, greasy spots or thick cases in this area can block the signal, creating the illusion of failure.
Principle of operation and diagnosis through the engineering menu
To test the performance of the component, you do not need to disassemble the device. The MIUI shell installed on the Redmi Note 9s includes a special engineering menu for testing iron, accessed through the standard Phone application by entering a secret code.
You need to type ##6484## on the dial keyboard. Once you enter the code, the CIT menu will open, where all the hardware modules of the smartphone are listed, and find the item "Proximity Sensor" or "Proximity Sensor" in the list and click on it to start the test.
- 📱 Close the top of the screen with your palm and look at the metrics – they should change from 5.0 to 0.0.
- 👁️ Remove your hand and make sure the values return to their original state without delay.
- 🔄 If the numbers don’t change, try clearing the sensor area of dust and grease.
In the test, the system reads data directly from the hardware controller, bypassing software filters, which allows you to determine whether the problem is physical (dirty, breakdown) or software (calibration failure). If there is a reaction in the CIT menu, but in life there is no problem, the problem is in the software settings.
Procedure for calibration of the proximity sensor
It often happens that a physically fit sensor is not working properly because of lost thresholds. Calibration returns factory sensitivity settings. On the Xiaomi Redmi Note 9s, this procedure can be manually performed through the same engineering menu that was used for the diagnosis.
After you enter the Proximity Sensor test, press the Calibration button. The screen can go out or change color. You will need to remove all items from the top of the phone and press Pass or OK when the system asks you to vacate the area. Then, conversely, close the sensor tightly and confirm the action.
☑️ Checklist of correct calibration
If automatic calibration doesn’t work, you can use third-party utilities from the Google Play store, such as “Proximity Sensor.” Reset/Fix». These applications force the rewriting of configuration files that are responsible for sensor sensitivity. MIUI more effectively.
⚠️ Note: Do not calibrate if the screen is thick with a black frame over the sensor, the results will be incorrect, and the phone will think that it is constantly in the ear.
Program conflicts and MIUI settings
Sometimes it's not hardware, but software conflicts. The MIUI shell has many features that can interfere with the basic modules, such as pocket mode or aggressive energy savings can block the infrared sensor from working properly.
Check settings in Settings → Lock and Protection → Mode in your pocket. If the feature is activated, try turning it off and check if the problem has gone away.
The following factors can cause failures:
- 📞 An outdated version of the firmware with bugs in drivers.
- 🛡️ Third-party antiviruses that block sensor access.
- 📲 Conflicting Call Management Apps.
It is recommended to update the system to the latest available version via Settings → About Phone → System Update. Xiaomi developers regularly release patches that correct peripheral errors. If the problem appeared after the update, you may need to reset.
What do you do if nothing helps?
Influence of accessories and external factors
Owners of Redmi Note 9s often forget that accessories directly affect the operation of sensors. Low-quality protective glass can have an opaque black frame that physically blocks the range of the distance sensor, and even micro-shifting such glass when dropped can create a problem.
Also, magnetic rings for holders in a car are negatively affected if they are glued too close to the upper end. The magnetic field can interfere with the electronic components, although the proximity sensor is primarily optical. Dirt and skin fat create a layer that scatters the IR ray.
Table of common problems and solutions:
| Problem. | Probable cause | Decision |
|---|---|---|
| The screen's not going out. | Dirt or film | Wipe the top face. |
| The screen goes out on its own. | False positive | Recalibrate the sensor |
| The indicator is shining | Failure of the | Reset the device |
| No reaction in the test. | The plume break | Repairs at the service |
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In 80% of cases, the problem is solved by simply cleaning the top of the screen or replacing a poor-quality protective glass.
Hardware repair and replacement of the component
If software and cleaning methods fail, there is likely a physical breakdown. On the Xiaomi Redmi Note 9s, the proximity sensor is often part of a flexible print plume or integrated into the display module. Replacing it requires fine electronics skills and tools.
Replacement requires removing the back cover (preheating the perimeter), disabling the battery and dismantling the metal frame. The sensor module can be soldered to the board or connected through a connector. Self-repair without experience can damage other components.
The cost of the original sensor plume is relatively low, but the job of replacing it requires precision. If you're not sure about your abilities, you'd better go to an authorized service center. Incorrect installation can cause the phone to lose network visibility or leakage.
⚠️ Note: When you disassemble your smartphone, you automatically lose your warranty. If the device is warranty, contact the official Xiaomi service.