How to set up the proximity sensor on Xiaomi Redmi 9T: the full guide

The proximity sensor in Xiaomi smartphones is a small but critical element that is responsible for automatically turning off the screen during phone calls. On the Redmi 9T model, the sensor sometimes works incorrectly: the screen does not go out when it is brought to the ear or, conversely, does not turn on after the call is completed, the problem can be in software failures and physical contamination of the sensor.

Many users mistakenly believe that a proximity sensor malfunction is a reason to contact a service center. However, in 80% of cases, the problem can be solved by yourself, correctly configuring or recalibrating the sensor. In this article, we will analyze all the available methods of setting, including hidden engineering menus, and also explain how to diagnose hardware malfunctions.

The Redmi 9T's feature is that the proximity sensor is combined with the light sensor (often confused because of its proximity), which means that one's malfunction can affect the other, for example, if the screen doesn't adjust brightness automatically, it can indirectly indicate proximity sensor problems.

Before you start settings, make sure that your device has the current version of MIUI installed. Old firmware (below MIUI 12.5) had bugs related to processing signals from sensors. You can update the system in the Settings menu → About phone → System Update.

Where is the proximity sensor on the Redmi 9T

On the Redmi 9T, the proximity sensor is located at the top of the screen, to the right of the front camera, and it's a small circular hole (~2 mm in diameter) under the display glass, and next to it is a light sensor, which is easy to confuse, but functionally they're different.

• 📱 Approximation sensor – responsible for turning off the screen when holding the phone to the ear.
• 🌞 Light sensor – adjusts the brightness of the screen depending on the ambient light.

To accurately identify the proximity sensor, put a flashlight on the top of the phone, the proximity sensor should not respond to light (unlike the light sensor), and you can also use the test through the engineering menu, which will show the current readings of the sensor.

Important: The Redmi 9T has an infrared approach sensor (as opposed to the capacitive sensors in some flagships), which means it can fail when it gets moisture or gets heavily contaminated, and if you notice that the screen is acting strange after visiting a bath or rain, it probably requires drying.

⚠️ Warning: Do not try to clean the sensor with alcohol or liquids! Infrared sensor is sensitive to aggressive substances. Use only a dry soft brush (for example, for camera lenses) to clean).

How to turn on or off the proximity sensor

In standard MIUI settings, there is no separate proximity sensor switch, but it can be monitored through call settings. Here's how to do this:

1. Open the phone application (pipe icon).
2. Click on the three dots in the top right corner and select Settings.
3. Go to the Calls section → Additional settings.
4. Find the Approach Sensor option (in some versions of MIUI, it may be called Automatic Screen Shutdown).
5. Activate or deactivate the slider.

If this option is not on the menu, then your device is using a simplified version of the firmware (for example, for the European region), in which case you will have to use an engineering menu or third-party applications.

Turning off the proximity sensor is not recommended, as it will lead to accidental taps during conversations, but a temporary shutdown can help diagnose the problem: if the screen stops going out after the sensor is deactivated, the problem is definitely there.

Call the phone and hold it to your ear (the screen should go out)

Move the phone away – the screen should turn on in 1-2 seconds

Repeat the test 3-4 times in a row

Check the sensor response in the dark and in bright light-->

Configure through the engineering menu (codes for Redmi 9T)

The engineering menu is a hidden settings section that lets you test the hardware components of a smartphone, including sensors. There are two working ways for the Redmi 9T to get there:

Method 1: through code

1. Open the Phone app.
2. Enter the combination: ##6484## (for sensor test) or #4636## (general engineering menu).
3. Select Proximity Sensor (approximation sensor).

Method 2: Through the application

If the codes don't work (for example, due to operator restrictions), install the MTK Engineering Mode app (for MediaTek processors). Redmi 9T is built on a Snapdragon 662 chip, so the shortcut Master is the right alternative.

In the engineering menu you will see the current readings of the sensor:

• Value is a numerical value (usually 0 is an object close, 5 is an object far away).
• Status is the status (FAR or NEAR).

For sensor calibration:

1. Close the sensor with your hand (or hold the phone to your ear).
2. Press Calibrate (if the option is available).
3. Open the sensor and press Calibrate again.

⚠️ Warning: Do not change Max Value and Min Value settings manually unless you are sure of their value! Incorrect settings can lead to complete inoperability of the sensor.

Testing the proximity sensor without calls

It's not easy to check the sensor only when you're making calls, and fortunately, there are ways to test it without having to call someone.

Method 1: Sensor Test application

Install the Sensor Test app from Google Play. It shows all the sensors in real time. For Redmi 9T, it's important to select the Proximity tab and watch the change in values when you hold your hand to the top of the screen.

Method 2: Using the Hidden MIUI Test

If the sensor shows a value of 0 in the test even when the phone is lying on the table, this indicates a hardware malfunction (for example, a departed plume or a damaged sensor), in which case it will require disassembly of the device.

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Before testing, remove the cover and protective glass — they can block the sensor signal. Also make sure that the screen is not greasy spots or scratches in the sensor area.

What to do if the proximity sensor is not working

If after all the manipulations the sensor is still not functioning, use this troubleshooting instruction:

• 🔄 Reboot your phone. Sometimes sensor failures are due to temporary system errors.
• 🧹 Clean the sensor. Use a soft brush or compressed air (a canister to clean the appliances). Don't blow with your mouth - moisture from your breath can make the problem worse!
• 📱 Reset the settings. Go to Settings. → System system → Resetting settings → Reset all settings (does not delete files, but resets system settings).
• 🔧 Update the firmware. → The phone. → System update check for updates. for Redmi 9T Critical corrections of sensors were made in MIUI 12.5.3. and MIUI 13.0.2.

If nothing has worked, hardware problems are likely:

• 🔌 Sensor plume (a common problem after falls or disassembly).
• 💧 Moisture has fallen under the screen (even if the phone did not sink, the condensate can accumulate).
• 🔍 Sensor damage (replacement required).

To diagnose the plume, you can slightly press the top of the screen (near the sensor) during the test. If the readings begin to change, there is a problem with contact. In this case, contact the service center. The average cost of repairing the proximity sensor on the Redmi 9T is 800-1,500 rubles (depending on the region).

Resetting sensor settings to factory

If you've been experimenting with the sensor settings through the engineering menu and it's not working properly, you can return the factory settings.

1. Open the engineering menu (code ##4636##)
2. Go to the Usage statistics tab (or Usage statistics).
3. Click on the three dots in the upper right corner and select Factory reset.
4. Confirm the action.

This method resets all sensor settings, including calibration of the accelerometer and gyroscope, and after resetting, it is recommended to restart the phone and retest the proximity sensor.

If the reset didn't work, try rolling back the firmware to the previous version.

1. Download the official firmware for Redmi 9T from Xiaomi website.
2. Go to Settings → About Phone → System Update → Three Dots → Select a firmware file.
3. Install the downloaded file and wait for the reboot.

⚠️ Attention: Firmware rollback erases all data on the phone! pre-backup through Settings → System system → Backup.

Frequent questions about the proximity sensor on the Redmi 9T

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The proximity sensor on the Redmi 9T is infrared, so it's sensitive to pollution and moisture. 90% of the time, it's done by cleaning, resetting or updating the firmware. Hardware failures (plug, sensor) require a service center to intervene.