Calibration of the proximity sensor on Xiaomi Redmi Note 9: 3 proven methods

Why does the Redmi Note 9's proximity sensor stop working?

The proximity sensor in Xiaomi Redmi Note 9 is responsible for automatically turning off the screen during a phone call when you bring the device to your ear. If it starts to crash, the screen does not go out, buttons are accidentally pressed, and the conversation is interrupted. The causes of problems can be different from software failures after the MIUI update to physical contamination of the sensor.

Most often, the problem arises after:

• 📱 Firmware updates (especially for unstable versions) MIUI Beta)
• 💥 A smartphone crash or hit (even if there is no external damage)
• 🔧 Disassembly of the phone (for example, to replace the battery)
• 🧹 severe contamination of the upper part of the screen (dust, fat, film residues)

Before you take your phone to the service center, try calibrating the proximity sensor manually, which solves the problem 80 percent of the time without any iron interference, and here are three methods, from the simplest to the most complex.

Method 1: Software reset sensor through engineering menu

The fastest method is to reset the sensor settings through a hidden engineering menu, which requires no root rights and works on all versions of MIUI for the Redmi Note 9 (including MIUI 12/13/14).

Instructions:

1. Open the phone app and enter the combination: ##6484## ⚠️ If the code doesn't work, try alternative #4636## → Go to the tab Information about the phone → Testing of equipment.
2. In the menu that opens, select Proximity Sensor.
3. Press Calibrate and wait for the process to be completed.
4. Reboot the phone.

Close all background apps | Make sure battery power > 20% | Remove cover and protective film from the top of the screen | Check that the sensor is not covered with dirt

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If you calibrate the sensor anyway, move on to the next method. Sometimes resetting through the engineering menu helps temporarily, but the problem comes back after the reboot, which is a sign of a deeper failure.

Method 2: Manual calibration using the Sensor Test application

If the standard engineering menu fails, use the third-party Sensor Test app (available on Google Play) that lets you manually test and calibrate sensors, including proximity sensors.

Step-by-step:

1. Install the Sensor Test application.
2. Open it and find the Proximity Sensor tab.
3. Click Calibrate and follow the on-screen hints: 📱 Hold your hand to the top of the screen (where the sensor is located). 🖐️ Remove your hand when a request appears. ✅ Repeat the action 3-5 times for fine-tuning.

Save the settings and restart the phone.

Critical error: If the app shows a sensor value of "-1" or "Not Available" - this means a hardware failure (damaged the plume or the sensor itself), in which case calibration will not help, you will need repairs.

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Before calibrating, wipe the top of the screen with an alcohol napkin - greasy prints and dust can block the sensor's infrared signal.

Method 3: Resetting phone settings to factory

If the software methods don't work, the last option is hard reset, which will delete all the data from the phone, but it will return the original sensor parameters.

• 🔄 The sensor stopped working after the update. MIUI.
• 📵 The problem arose after installing custom firmware.
• 🔧 Previous methods have failed to produce results.

Resetting instructions:

1. Make a backup of the data through Settings → About Phone → Backup.
2. Go to Settings → Additional → Recovery and Reset.
3. Select Reset and confirm the action.
4. After restarting, check the proximity sensor.

⚠️ Warning: If the sensor doesn't work even after the reset, the problem is almost certainly hardware: 🔌 Oxidation or break of contacts of sensor plume. 💥 Cracking in sensor after falling. 🔋 Motherboard malfunction (rarely, but it happens) In this case, contact the Xiaomi service center.

How to check if the proximity sensor is working?

Before you calibrate the sensor, make sure it's really the problem.

1. Enter the code in the phone app: ##4636##
2. Go to the phone information tab → Testing equipment.
3. Select Proximity Sensor.
4. Put your hand to the top of the screen: ✅ If the value changes from 5.0 cm to 0.0 cm, the sensor is serviceable. ❌ If the value does not change or shows an error, the sensor is defective.

You can also use applications to test sensors, such as:

• CPU-Z (shows the state of all sensors)
• Phone Doctor Plus (tests the hardware).
• Sensor Box for Android (detailed diagnostics)

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If the sensor doesn't respond to the tests, but the screen goes out during the call, the problem may be the firmware, not the sensor itself. Try to roll back MIUI to the previous version.

Frequent errors in calibration of the proximity sensor

Many users make mistakes that negate all efforts to adjust the sensor, and here are the most common:

Another common mistake is trying to calibrate the sensor through root applications (e.g., the Xposed Framework). On the Redmi Note 9, this often leads to a bootloop if the firmware does not support root. If you are not a power user, avoid such methods.

Hardware causes of sensor malfunction

If the software methods didn't work, the problem could be hardware.

• 🔌 Sensor plume damage is a common problem after disassembling the phone, and the plume is thin and fragile, easily torn if handled carelessly.
• 💧 Contact oxidation – if the phone was exposed to rain or condensation, the contacts could corrode.
• 🔍 Infrared sensor contamination – dust, fat, or film glue residues block the signal.
• 💥 Cracking in the sensor – after a strong impact, the sensor can crack, even if the screen is intact.

If you're not sure about your skills, you should go to the service.

• Replacement of sensor plume – 1000-1 500 ₽.
• Cleaning contacts - 500-800 ₽.
• Replacement of the proximity sensor – 1,500–2,500 ₽ (depending on the module model).

⚠️ Note: Redmi Note 9 approximation sensor combined with light sensor. If after repair stopped working brightness auto-regulator - means the master damaged the common module.

FAQ: Frequent questions about the proximity sensor on the Redmi Note 9