Approximation sensor on Xiaomi Mi A3: setting and calibration

Problems with the proximity sensor on the Xiaomi Mi A3 smartphone can make using the device a nightmare, especially during long conversations.The screen either doesn't go out when you bring the phone to your ear, or, conversely, does not turn on when you remove the device.

Many users mistakenly believe that the malfunction is in the hardware and rush to carry the gadget to the service center. However, in 90% of cases, the situation is corrected by software calibration or the correct configuration of system parameters. In this article, we will discuss all the ways to troubleshoot the problem in detail.

We will look at both standard methods through the engineering menu and more advanced methods using the ADB-It is important to understand that Xiaomi Mi A3 It runs on pure Android (Android One), so some methods are familiar to shells. MIUI, This may be different or require adaptation.

The principle of operation and the main symptoms of malfunction

The proximity sensor in the Xiaomi Mi A3 is an infrared sensor located at the top of the display, next to the speaker, whose task is to determine the distance to the object. When you bring the phone to your face, the sensor detects the reflection of the IR beam and signals the system to turn off the touchscreen and turn off the matrix.

If this mechanism is not working properly, you may experience a number of unpleasant phenomena, such as when you're talking to your cheek, you may accidentally press the reset button or turn on the speakerphone, sometimes the screen remains black even after you've removed the phone from your ear, and you have to lock the device with a button.

A common cause of failure is software conflict or driver failure after a system update, and sensor performance is affected by wide black-framed protective glass that can overlap the sensor core, and it is important to distinguish between software failure and physical failure.

  • 📱 The screen does not go out when you bring the phone to your ear during a ringing.
  • 📱 The display remains black after the conversation is over.
  • 📱 Accidental tapping of the cheek or ear during a conversation.
  • 📱 Involuntary turn on speakerphone without touching the screen.

⚠️ Attention: If after all the software manipulations, the sensor continues to operate chaoticly, there may be a problem in the physical damage to the plume or the sensor itself.

Preparation of the smartphone for diagnosis

Before you get to the complex settings, you need to eliminate the trivial factors that interfere with the correct operation of the sensor. First of all, check whether there is a protective glass or film on the screen that covers the area above the speaker. Even a minimal offset can block the IR beam.

The second important step is cleaning the top of the body, and the fat, dirt or dust that has accumulated in the speaker's grid can distort the sensor readings. Wipe the area with a soft cloth soaked in an alcohol solution. Make sure there is no pile from the case in the hole.

It's also worth checking if you have phone or screen monitoring apps, if you have any third-party callers or launchers that can intercept the sensor, and if you want to keep the experiment clean, you'd better temporarily shut down any suspicious programs.

☑️ Pre-calibration check

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Calibration through CIT Engineering Menu

The most efficient way to set up the proximity sensor on the Xiaomi Mi A3 is to use the built-in engineering test menu (CIT), which allows you to check the operation of all sensors and reset them to factory values, accessed through a special code.

Open the Phone app and dial the combination ##6484##. If the menu doesn't open, try the alternative code ##4636##, although the former option is preferable for testing iron.

Inside the test, you'll see the current distance. Close the top of the screen with your palm, the value should change (usually from 5.0 to 0.0 or vice versa, depending on the software version). If there's no reaction, press Calibration or Start to start the calibration process.

Calibration process:




1.Push Start.




2. Remove your hand from the screen (green light should be lit).




3. Close the sensor with your hand (the indicator should go out).




4. Repeat 3-5 times according to the instructions on the screen.

Once the test is completed successfully, be sure to press the Pass or Save button to save the new settings. Without this step, calibration will not apply. Reboot the device and check the sensor's performance in a real call.

What if the code doesn't work?
On some global versions of Android One, access to CIT It can be limited to operator or firmware, in which case, try installing the Xiaomi Engineer Mode app from the Play Market, which emulates access to hidden system functions."> Sensitivity adjustment through ADB If standard methods have not yielded results, you can try to change the sensitivity threshold of the sensor through the debugging bridge (ADB). This method requires you to connect to a computer and have a basic command line knowledge, and it allows you to make changes to the system configuration files. First, you need to activate the developer mode. Go to Settings. → About the phone and quickly click 7 times on "Build Number." Then in the "Development by" menu, turn on "Debug by USB». Connect your smartphone to your PC. ADB You can try resetting the sensor settings or changing the correction factor. Commands can vary depending on the driver version, but a basic reset is often done through a cache clearing command. 💻 Install the drivers. ADB and Fastboot on the computer. 💻 Connect your phone and allow debugging on the screen. 💻 Enter the adb shell command to enter the shell. 💻 Use commands to reset the sensor calibration. It is worth noting that on pure Android, which is installed on the Xiaomi Mi. A3, depth of access ADB It may be limited in comparison with MIUI. However, trying to reset sensor configurations often helps to return factory settings that may have been lost. Below is a table that will help you determine the best way to calibrate or repair. Method Complexity Efficiency Risk of data loss Screen cleaning Low Average No Engineering menu (CIT) Average High No ADB As you can see from the table, the safest and most effective method is to use an engineering menu. It does not require special equipment and rarely leads to the loss of personal data. Reset to factory settings should be used only as a last resort. 💡Engineering menu CIT — It's a standard diagnostic tool built into the manufacturer, and it's safest and safest to calibrate. When software failures become critical and none of the calibration methods help, there is the last software argument – a complete data reset). This operation will return all system files, including sensor drivers, to their original state. It is important to understand that Hard Reset will delete all your photos, contacts and applications. Entering the recovery mode is via a combination of volume and power buttons. From the Recovery menu, select Wipe data/factory If that doesn't work, it's probably hardware or you need to flash it over the Fastboot and replace the system imagery. ⚠️ Warning: Flashing your device through Fastboot with the bootloader unlocked can lead to a loss of warranty. Frequently Asked Questions (FAQ) Why does the sensor fail after the screen is replaced? When replacing the display, often low-quality copies are used that lack or are incorrectly installed proximity sensor. Also, the wizard may have forgotten to connect the plume or damage it during assembly. Re-diagnosis is required from a specialist. Can a virus affect the sensor? In theory, malware can block access to system functions, but in practice this happens extremely rarely. Most often the problem lies in conflicting applications or system errors of Android, not viruses. Does the cover affect the operation of the sensor Daves, do some of the root? For standard calibration through the engineering menu, root rights are not required, but for deep editing of system configuration files through the ADB Third-party utilities may require superuser rights. 📊 How did you solve the sensor problem?Displayed the screen/removed the glass CITReset the phone settings Took to the service center