Modern smartphones, including the popular Xiaomi Redmi 9C NFC, feature a variety of sensors that make it easy to use. One key component is a proximity sensor that automatically turns off the screen when you hold the device to your ear, which prevents accidental cheekstrokes and saves battery power. However, in some situations, the standard logic of the sensor can cause inconvenience, requiring user intervention in the settings of the system.
Users often experience a situation where the screen goes prematurely (prematurely) or, conversely, does not turn off while the phone is near the ear. Owners of the Redmi 9C NFC can look for ways to deactivate this feature for specific tasks, for example, to listen to audio through the speaker during a call or use the phone as a stationary monitor. Complete software shutdown of the sensor at the level of the MIUI system without root rights is often impossible, but there are effective calibration methods and workarounds.
In this guide, we will take a closer look at the technical aspects of the sensor, how to adjust it correctly and how to solve problems with sticking or incorrect reaction. You will learn how to use engineering menus and third-party utilities to fine-tune sensitivity. Understanding the principles of operation of the infrared emitter will help avoid false positives and prolong the service life of the display.
Principle of operation and purpose of the sensor
The proximity sensor in the Xiaomi Redmi 9C NFC smartphone is a combination of an infrared LED and a receiver. It constantly emits an invisible beam and analyzes the reflected signal. When an object, such as a human ear, is close, the intensity of the reflected light changes, and the system receives a command to turn off the display matrix. It is a physical process that is difficult to ignore software without deep interference with firmware.
The main purpose of using this mechanism is to protect against random action. Imagine that during an important conversation you pressed the phone to your cheek and the screen went out. Without this sensor, you would accidentally press the hold button, reset the call or turn the microphone on speakerphone. However, in scenarios where the phone is lying on the table or used with a headset, the constant reaction to foreign objects in the upper part of the case can be annoying.
⚠️ Warning: Completely ignoring the proximity sensor readings can cause your cheek or ear to constantly activate the touchscreen during a conversation, which will entail dialing random numbers or enabling unnecessary features.
The sensor technology is independent of the operating system version, whether it's Android 10 or newer versions of MIUI. The hardware remains the same, only the data processing algorithm changes. In some cases, software bugs can lead the system to misinterpret the sensor data, believing that the phone is near the ear, even when it is lying on the table, which requires calibration or resetting.
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The proximity sensor is a hardware component that cannot be physically turned off without disassembling the phone, but it is possible to adjust its software processing.
Diagnostics of sensor faults
Before you try to disable or reconfigure the sensor, you need to make sure that the problem lies in its operation, and not in software failure or contamination. Often users look for ways to turn off the function when it is enough to simply wipe the top of the screen. On the Redmi 9C NFC model, the sensor is located in a narrow frame above the display, next to the conversational speaker.
For the initial diagnosis, you can use the built-in engineering test, which is a safe method that doesn't require third-party software, and you have to type in a special code in the Phone app, and then you open the hardware check menu, and you can see the real state of the sensor in real time.
- 📱 Enter the code ##6484## in the dialer to enter the engineering menu.
- 🔍 Find the "Proximity Sensor" or "Proximity Sensor" item in the list".
- 🖐️ Hold your palm to the top of the screen and remove it, watching for the change in values (usually from 5.0 to 0.0).
If the values change dramatically and clearly, then (hardware) is fine, and the problem may be in the software or the security glass. If the reaction is sluggish or the values do not change at all, you may need more serious intervention. In some cases, simple resetting of the system to factory settings helps, but this is a last resort.
Calibration methods through the engineering menu
The most effective way to solve problems with sensor malfunction on Xiaomi Redmi 9C NFC is its calibration, which “teach” the system to understand what distance is considered close and what is far. Calibration is especially relevant after replacing the display or protective glass, since the thickness of the new layer can distort the IR beam.
To do the calibration, you'll need to access the engineering menu again, and the process is this: after you enter the proximity sensor test, an instruction will appear on the screen to close the sensor with your finger, you close the top of the screen, the system will record the value "close", then asks you to remove your finger and fixes the value "far".
☑️ Checklist for calibration
After passing the test, press the Pass or Save button so that the new parameters are recorded in the device memory, and it is important to perform this procedure in good light, but without direct sunlight falling on the sensor, since bright light can interfere with the IR receiver.
| Parameter | Normal value. | Problematic significance | Action. |
|---|---|---|---|
| Distance (cm) | 0 - 3 (close) | Constantly 0 | Sizing |
| Status | Near / Far | Only Near. | Software testing |
| Raw Data | Low values | Cleaning the sensor | |
| Reaction | Instant. | Delay > 1 sec | Resetting settings |
If the calibration doesn't work and the sensor continues to behave inadequately, there may be a problem with the hardware plume or the module itself, in which case software methods, including shutdown attempts, may not produce a lasting result.
Use of third-party applications
Because standard MIUI settings don't have a "Disable Approach Sensor" slider, users often turn to third-party software. There are many utilities on the Google Play Store that can intercept sensor control. One popular solution is the "Proximity Sensor Reset/Fix" app, which allows you to reset or force the logic of the operation to change.
These applications work on the principle of overlay (overlaying on top of the system), they can block a standard call to turn off the screen or, conversely, emulate pressing if the sensor is stuck. However, it is worth considering that installing applications with deep access rights can reduce the security of your device.
⚠️ Note: Sensor management applications often require permissions to draw over other windows and access system settings. Use only proven high-rated software to avoid data leakage.
Alternatives to specialized tools are automation applications like Tasker or MacroDroid, which can create a scenario where you can say, "If you're calling and you're less than 5 cm away, you don't turn off the screen." It's a more flexible approach, not to turn off the sensor completely, but to change the way it behaves in specific situations.
Risks of using third-party software
Hidden settings of the developer and ADB
For advanced users who don’t want to install unnecessary applications, there is a method of configuring through USB debugging and ADB (Android Debug Bridge) commands, which allows you to make changes to system configuration files that are not available through the usual interface Xiaomi Redmi 9C NFC.
First, you need to activate the developer mode. → About the phone and quickly press 7 times on the item "Version" MIUI". After the inscription "You became a developer" appears, go to the advanced settings and turn on Debugging by USB.
If you connect your phone to your computer, you can (try) input commands that affect sensor behavior. However, there is no universal command to shut down completely, because it depends on the drivers of the particular device.
adb shell settings put system proximity_on 0It is worth noting that on new versions of Android and MIUI shells, such commands can be ignored by the security system, in which case root access is required, obtaining which will void the warranty and may disrupt the operation of banking applications (Google Pay, Mir Pay).
- 💻 Install the drivers. ADB computer.
- 🔌 Get Redmi on board. 9C NFC cable-in-file transfer mode.
- ⌨️ Enter the command in the terminal and check the result.
Physical Factors and Screen Protection
Often the reason for the proximity sensor malfunction on the Xiaomi Redmi 9C NFC is trivial — the protective glass or film. If the accessory closes the area above the speaker, it distorts the IR beam. The light is reflected from the inner surface of the glass and hits the receiver back, creating the illusion that the phone is near the ear.
The solution could be to neatly cut the hole in the protective glass above the sensor, or replace the accessory with a model labeled "2.5D" or specially designed for this model, which takes into account the geometry of the sensor, and it is also important to monitor the purity of this area: greasy spots from the fingers or dust in the case can block work.
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If you use a solid protective glass, try to wipe the sensor area with an alcohol napkin before an important conversation – this often removes static electricity and fat film.
In some cases, temporary removal of the case helps. Tight bumpers with high sides can block the view of the sensor, especially if the phone is lying on the surface, check if the case is pressing on the upper end of the device.
Alternative solutions to the problem
If your goal is not to turn off the sensor for the sake of turning it off, but to solve a specific problem (for example, the phone does not hang up or goes out in your pocket), there are simpler ways. To prevent calls from your pocket, use the “Block in your pocket” function, which uses the same sensor but with a different algorithm, or turn on “In your pocket” mode in the lock settings.
For those who want to listen to the speaker, the easiest way to do this is to press the hands-free button right after you start the call, which will programmatically switch the audio stream and change the priorities of the sensors. In the call settings, you can also find the "Draw to turn on" item, which will prevent the screen from turning on when you lift it, but will not necessarily turn off the screen when you put it.