Calibration of the proximity sensor on Xiaomi Redmi 9T: a complete guide with proven methods

The proximity sensor in the Xiaomi Redmi 9T is a small but critical component that shuts down the screen during phone calls. When it doesn't work properly, you run into annoying problems: the screen goes out on its own, doesn't respond to touch when you call, or, conversely, stays active when you hold the phone to your ear, which not only interferes with comfortable communication, but can also lead to accidental taps during a conversation.

Many users mistakenly believe that sensor malfunction is a hardware problem that needs repair. However, 80 percent of the time, the fault is software failure or miscalibration. The good news is that you can do the setup procedure yourself in 5 to 10 minutes without having to use a service center. In this article, we'll look at all the working methods, from standard MIUI tools to hidden engineering menus and manual calibration through ADB.

Before you start setting up, make sure that the problem is really related to the proximity sensor. Sometimes similar symptoms are caused by protective films, metal covers or even contamination of the speaker. Do a simple test: open the Phone application, dial a conditional number (for example, #), and hold your palm to the top of the screen (where the sensor is located). If the screen does not go out or reacts with a delay, it is time to start calibrating.

Causes of proximity sensor failures on Redmi 9T

The proximity sensor in Redmi 9T uses an infrared LED and a photodiode to determine the distance to an object, and its malfunction can be due to both hardware and software factors.

• 📱 Software failures: Firmware errors MIUI, Especially after updates, they often get the calibration of the sensors, which is the most common reason that's easy to fix.
• 🔧 Mechanical damage: A smartphone hit or fall could displace the sensor or damage its contacts, in which case it will require diagnostics in the service.
• 🛡️ Pollution or obstruction: Dust, moisture or thick protective film in the sensor area blocks the infrared signal.
• 🔄 Application Conflict: Some programs (e.g. modified launchers or battery-saving applications) may interfere with sensors.
• 🔋 Battery discharge: At a critical charge level (below 5%), the system can turn off sensors to save energy.

Interesting fact: The Redmi 9T uses the STK3311 approach sensor (or similar), which calibrates automatically every time you turn on the smartphone, but if the automatic setup fails, manual adjustment is required.

Before you proceed to calibration, eliminate external factors:

1. Remove the cover and protective film from the top of the screen.
2. Wipe the sensor area (near the front camera) with a dry wipe.
3. Reboot your phone – sometimes it solves the problem of temporary crashes.

How to check the operation of the proximity sensor

Before calibrating, you need to make sure that the sensor is really defective. MIUI has hidden diagnostic tools that will help assess its condition.

Method 1: Testing through the Engineering Menu

1. Open the phone app and dial the combination: ##6484##.
2. Select Proximity Sensor (Proximity Sensor).
3. A graph or numerical values (usually 0 to 5) will appear on the screen.
4. Close the sensor with your hand, the values should change to 0 (or close to it). Remove your hand, the values will return to 5.

Method 2: Checking with Sensor Test

If the engineering menu is not available, install the Sensor Test app from Google Play (such as Phone Doctor Plus or Sensor Box). In the Proximity section, you will see the real sensor metrics. Normal values:

• 👍 Distance (arm removed): 5.0 cm (or 5 in the engineering menu).
• 👎 Close distance (hand closes sensor): 0.0 cm (or 0).

The critical point is that if the sensor is 0 regardless of the position of the hand or the values do not change at all, this indicates a hardware malfunction. Calibration is not going to help here, you need to replace the sensor.

Method 1: Calibration through the engineering menu (without root)

The most reliable method that works on most Xiaomi devices, including the Redmi 9T. It does not require superuser rights and takes less than a minute.

Step-by-step:

1. Open the Phone app and enter the code ##6484## (or #4636## → Service tests → Proximity Sensor).
2. The MTK Engineer Mode (or similar) menu will appear on the screen. Select Hardware Testing → Sensors → Proximity Sensor.
3. Press the Calibrate button. The sensor will automatically set up.
4. Once completed, restart the phone.

If there is no Calibrate button, try an alternative path:

1. Select the Single Item Test → Proximity Sensor.
2. Close the sensor with your hand and wait until the values are zeroed.
3. Remove your hand, the values should return to 5.
4. Then, click Menu (three dots) → Save (save).

Close all background applications

Make sure that the battery is > 20%

Remove the cover and film from the top of the screen

Remember the original sensor values-->

⚠️ Attention: Some firmware MIUI If the code ##6484## doesn't work, try alternative combinations:

• ##4636## → Service tests
• #36446337## (for some regions)

Method 2: Manual calibration via ADB (for advanced users)

If standard methods don't work, you can calibrate it using the Android Debug Bridge (ADB), which requires you to connect your phone to your computer, but it gives you a more accurate result.

What you need:

• 🖥️ A computer with installed Xiaomi drivers and ADB.
• 🔌 USB-cable (preferably original).
• 📱 Included debugging by USB on the phone (Settings) → The phone. → Version. MIUI → 7 times press to unlock Developer Settings, then enable Debugging by USB).

Instructions:

1. Connect Redmi 9T to your computer and confirm debugging permission.
2. Open the command line (Win) + R → cmd) and enter: adb shell su echo 1 > /sys/class/sensors/proximity/proximity_calibrate
3. If the command didn’t work, try an alternative route: adb shell am start -n com.android.settings/.TestingSettings Then manually find the sensor calibration section.
4. Reboot the phone.

⚠️ Attention: Teams ADB If you have a Permission denied error after you enter a command, you have your device blocked access to system files without root rights.

💡

If you don’t have ADB experience, use Minimal ADB and Fastboot.It makes it easy to enter commands and doesn’t require a full Android SDK installation.

Method 3: Reset sensor settings via Safe Mode

Sometimes proximity sensor failures cause conflicting applications, so to check for this, run your phone in Safe Mode, where only system programs are running.

How to turn on Safe Mode:

1. Press the power button before the turn off menu appears.
2. Press and hold the option “Switch off power (or turn off)” before a request to switch to Safe Mode appears.
3. Confirm the action. The phone will reboot with the Safe Mode label at the bottom of the screen.

In safe mode:

1. Check the proximity sensor (for example, call another phone).
2. If the sensor is working normally, the problem is in one of the installed applications.
3. Remove the recently installed programs until you find the culprit.

To exit Safe Mode, simply restart your phone.

Method 4: Resetting settings to factory (last resort)

If all previous methods failed, the last option is to reset the phone to factory settings, which will delete all user data, but return the sensors to their original state.

How to reset:

1. Back up your important data (Settings → About Phone → Backup).
2. Go to Settings → Additional → Recovery and Reset.
3. Select Resetting → Erase all data.
4. Confirm the action and wait for the process to be completed (it will take 5-10 minutes).

⚠️ Warning: Once reset, the phone will return to a "out of the box" state, you will need to reset your Mi Account, connect to Wi-Fi and restore data from the backup. Do not interrupt the reset process - this can damage system files.

If even after resetting, the proximity sensor is not working properly, it indicates a hardware malfunction. In this case, contact the Xiaomi service center for diagnosis.

Additional Tips for Caring for the Approximation Sensor

To avoid repeated failures, follow these guidelines:

• 🧼 Clean the top of your phone from dust and grease regularly (use a lilac-free wipe).
• 📵 Avoid cases with metal elements or magnets in the sensor area.
• 🔄 Update the firmware MIUI Up to the latest version – new updates often fix sensor errors.
• 🚫 Do not install applications to “optimize” sensors from unverified sources.

If you talk on your phone frequently in high humidity (such as rain), the sensor may temporarily fail, in which case dry your phone in a warm place (but not in direct sunlight!) for 1-2 hours.

💡

Regular cleaning of the sensor and avoiding mechanical stress prolong its life, and 90% of the time, the proximity sensor problems on the Redmi 9T are solved by software methods without repair.

Frequently Asked Questions (FAQ)