Many smartphone owners experience a phone call where the screen suddenly goes out and the voice of the person they are talking to is cut off, a classic approach sensor behavior that blocks random cheekstrokes, but in budget models like the Xiaomi Redmi 9C, this mechanism often works incorrectly due to design or factory defects.
Users have to find ways to force this feature to communicate comfortably. In this article, we will discuss in detail the software methods for bypassing the lock screen, including hidden engineering menus and system commands, you will learn how to control the behavior of a smartphone without having superuser rights.
It's worth noting that completely disabling the sensor can cause the screen to respond to ear touches during a conversation.However, for many, this is less of a bad thing compared to constant communication failures. We'll look at safe tuning methods that won't violate the device's warranty.
The reason for the sensor incorrect operation on the Redmi 9C
The main cause of the problems in the Redmi 9C is a software calibration failure or the physical location of the sensor under the display layer. Unlike the older models, where the sensor had a separate window, here it is hidden. Pollution of the top of the screen with greasy traces or dust in the speaker grid can distort the readings.
The quality of the protective glass also affects: Cheap films often block infrared radiation, which makes the system think that the phone is held to the ear even when it is lying on the table. MIUI sometimes reacts aggressively to the slightest changes in lighting, blocking the display preventively.
⚠️ Warning: Before making changes to system settings, make sure there are no cracks in the top of the screen.Mechanical glass damage can make software shutdown the only working solution.
There is a table of the main symptoms indicating the need for intervention in the operation of the sensor:
| Symptoms. | Probable cause | Difficulty in eliminating |
|---|---|---|
| The screen goes out immediately after the call starts. | Calibration error | Low. |
| You can’t hear the phone while you’re holding it to your ear. | Locking the speakers | Medium |
| The screen does not light up when you are away. | Sensor sticking | Tall. |
| Accidental call dumps in your pocket | Extreme sensitivity | Low. |
Understanding the nature of a malfunction helps you choose the right solution, and if a problem is caused by a software failure, resetting or reconfiguring through an engineering menu often helps.
Using the Engineering Menu for Diagnostics
The most effective way to check and reconfigure the sensor is to log into a special diagnostic menu, open the Phone app and enter a secret code. Xiaomi devices with MediaTek processors, like the Redmi 9C, use a universal command.
Enter the dialer code ##6484## or #4636##. If the menu doesn't open, your firmware version may block that access, in which case you will need to use third-party utilities or ADB-The teams that will be discussed below.
In the CIT menu that opens, you'll find the item "Proximity Sensor," and you'll see the current readings on it, and you'll close the top of the screen with your hand, and the values should vary from 5.0 to 0.0, and if there's no change, the sensor is physically malfunctioning.
☑️ Diagnosis in CIT menu
If the values jump randomly, it indicates a software glitch. In this section, the Calibrate button is often available. When you press it, follow the instructions on the screen: usually you need to remove your hand, then close the sensor and remove it again. After successful calibration, the problem can disappear without completely turning off the function.
Disconnecting through hidden Android settings
In some versions of the MIUI shell, there is a hidden switch that allows you to ignore the proximity sensor readings, which is not displayed in the usual settings menu, but is available through search or special commands.
Try Settings → Apps → All Apps. Find Phone (or Calls) in the list. In some cases, there is an Incoming Calls section where you can check the Approximation Sensor box, but newer versions of Android often close the path.
Alternatively, use the command through the developer menu. Activate the developer mode by tapping the build number seven times in the About Phone section. Then, in the Developer menu, look for sensor-related or debugging options.
⚠️ Warning: Do not change the settings in the developer menu unless you are sure of their purpose.This can lead to unstable operation of the entire system, not just the phone book.
If standard methods fail, you can use the command via ADB (Android Debug Bridge), which requires a connection to a computer.
adb shell settings put system proximity_on_off 0This command forces the system variable to change, but it's worth remembering that once the device is restarted, the setting can reset if it's not locked into the firmware configuration file.
Application of third-party fixing applications
When Xiaomi’s system constraints prevent you from changing settings directly, Google Play apps come to the rescue, and they work on top of the system, intercepting the sensor signal and ignoring it when making calls.
A popular solution is the Proximity Off or Sensor Disabler app, which is simple: they create a virtual layer that blocks the data from the sensor to the call system, and that allows the screen to stay on.
- 📱 Proximity Off is a simple application with a single activation button, requires minimal resolutions and runs in the background.
- 🛠️ Sensor Disabler is a more advanced tool that allows you to choose which applications to disable the sensor for.
- 🔧 Fix Proximity Sensor is a utility that attempts to automatically recalibrate the sensor before every call.
Installation of these programs requires special permissions. Once installed, you will need to launch the application and press the Disable or Fix button. The interface is usually minimal.
Security of Third Party Applications
It is important to monitor the updates of such slits. After updating the version of MIUI or Android, the mechanism of operation may be broken, and the application will need to be reinstalled or replaced with an analogue.
Radical methods: resetting and flashing
If software failures are deep, you may need to reset your settings completely to factory settings, which will delete all user data, so back up your contacts and photos beforehand.
To perform the reset, go to Settings → About Phone → Reset. Select “Erase All Data.” Once turned on, the phone will look like new, and the sensor calibration will return to its original factory values. Often this solves the problem if it is not related to hardware.
In extreme cases, users resort to flashing the device to a global version or custom firmware (for example, LineageOS). Custom firmware often lacks aggressive Xiaomi energy saving algorithms, which cause false positives.
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Before flashing, be sure to unlock the bootloader through the official Mi Unlock website.Be aware that this voids the warranty and requires waiting 7 days after the Mi acc is tied.
The flashing process is complex and requires technical knowledge, and a mistake can turn a phone into a brick, so this method is recommended only for advanced users who are willing to risk the device for full functionality.
Physical limitations and screen protection
The physical factor is also not to be discounted. In the Redmi 9C, the sensor is located at the top of the display. Any sticker, even a transparent one, if it doesn't have a special cutout or is not designed for this model, can block the IR beam.
Try removing the security glass and wiping the screen with a microfiber. If the problem is gone, it was the accessory. It's also worth checking the case: some dense bumpers can slightly press on the edge of the screen, creating a "ghost touch" effect or blocking the sensor.
The table below shows the compatible types of protective glass that are less likely to cause problems:
| Type of protection | Impact on the sensor | Recommendation |
|---|---|---|
| Hydrogel film | Minimum | Recommended |
| Black-framed glass | High (overlapping) | Not recommended |
| Glass without frames | Average. | Accurate fitting is required |
Sometimes it helps to simply stick a small piece of black tape over the sensor (if it is visible) or, conversely, to create a micro hole in the protective glass if it closes the active area.
⚠️ Warning: Don't try to disassemble the phone yourself to clean the sensor if you don't have experience.At Redmi 9C The sensor can be soldered into the display plume, and its damage will result in costly repairs.
Frequently Asked Questions (FAQ)
Will the sensor shutdown affect other functions?
Will the setup reset after the MIUI update?
Can the sensor driver be removed completely?
Why is this happening more often on Xiaomi 9C than on others?
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Turning off the proximity sensor is a compromise solution, which eliminates the problem of the fading screen, but requires getting used to a new way to finish calls.
In conclusion, controlling the proximity sensor on Xiaomi 9C requires a comprehensive approach. Start by calibrating through the engineering menu, then try the software fixes. If nothing works, using third-party blocking apps will be your salvation. Remember that regularly cleaning the top of the screen from contamination is the best prevention of failures.