If your Xiaomi Redmi Note 9 Pro screen doesn't go out during a call or, conversely, it turns off for no reason, the problem is most likely the proximity sensor. This small but critical element is responsible for the automatic actions of the smartphone when you lift it to the ear, preventing accidental pressing. However, many users face difficulties in finding its location: unlike the front camera or speaker, the sensor is visually invisible.
In this article, we’ll take a look at the exact location of the proximity sensor in the Redmi Note 9 Pro (including the Redmi Note 9 Pro Max and Redmi Note 9S), explain how to identify it without disassembling the phone, and provide instructions for troubleshooting, and learn why the sensor may not work properly and how to fix it yourself, from software calibration to hardware repair.
Where exactly is the proximity sensor in the Redmi Note 9 Pro
In the Xiaomi Redmi Note 9 Pro, the proximity sensor is integrated into the top of the screen, next to the front camera and light sensor, more specifically, the small circular hole to the left of the selfie camera (when viewed in the standard position), and the photo below shows its typical location:
Photo of the location of the sensor (clickable)
It's important to understand that the Redmi Note 9 Pro uses an infrared (IR) proximity sensor, not an ultrasonic sensor, which means it emits and receives light signals, not sound waves, which is why it's placed next to other optical sensors to unify the design.
If you are not sure you have found the right item, compare it to the other holes in the top panel:
- 📸 Front camera - the largest round hole in the center.
- 💡 Light sensor – usually to the right of the camera, slightly smaller in size.
- 🔄 The proximity sensor to the left of the camera can be almost invisible.
- 🔊 A conversational speaker is a slit-like hole above or below sensors.
How to visually distinguish the proximity sensor from other sensors
In order not to confuse the proximity sensor with a microphone or light sensor, pay attention to its characteristic features:
| Sensor | Appearance | Location. | Function |
|---|---|---|---|
| Approximation sensor | Tiny round hole (1–1.5 mm), often with matte surface | Left of the front camera. | Turns off the screen when you bring the phone to your ear |
| Light sensor. | Transparent or semi-transparent hole (2-3 mm) | Right of the front camera. | Adjusts the brightness of the screen |
| Front camera. | Large circular hole (4-5 mm) with a lens | Centered to the upper frame | Selfie and video calls |
| Microphone | Fine perforation or slit | Below or above the sensors | Capturing sound during a conversation |
You can use a flashlight to identify accurately, point the light at an angle to the top of the phone, and the proximity sensor doesn't have to be visible (unlike the light sensor), because it blocks visible light, allowing only infrared light to pass through.
⚠️ Warning: Don't confuse the proximity sensor with an infrared port (if your model has one).The latter is usually located on the upper end of the case and used to control appliances (such as TVs). IR-port.
Causes of failure of the proximity sensor and their signs
If the proximity sensor is malfunctioning, this is manifested by the following symptoms:
- 📵 The screen does not go out during the call, even when the phone is pressed to the ear.
- 🔄 The screen is spontaneously turned off during normal use (for example, when reading).
- 🔍 The sensor reacts with a delay (extinguishes after 2-3 seconds after application).
- 🚫 The function "Smart blocker" in the settings of calls does not work.
The main causes of such problems are:
- Sensor pollution – dust, grease, or protective film block the infrared signal.
- Software failure – errors in the firmware or Android settings.
- Mechanical damage - cracks on the glass, impacts, moisture.
- Fault of the plume - oxidation of contacts or break of connection with the motherboard.
💡
Before diagnosing the sensor, check if it is disturbed by a cover or protective glass. Often the problem is solved by simply cleaning the upper frame with an alcohol tampon.
To rule out software problems, run a sensor test through an engineering menu or third-party apps (such as Phone Doctor Plus or Sensor Test). If the test shows that the sensor is not responding at all, the problem is likely hardware.
How to check the proximity sensor on the Redmi Note 9 Pro
There are several ways to diagnose a sensor, from built-in MIUI tools to specialized utilities, and let's take them in order.
Method 1: Use of Engineering Menu (CIT)
MIUI has a hidden engineering menu where you can test all the sensors.
- Open the Phone app.
- Type the combination: ##6484## (or #4636## for older versions).
- Select the Hardware Testing option → Sensor.
- Find the Proximity Sensor string and cover the sensor with your hand.
If the value changes from 5 (no obstacle) to 0 (there is an obstacle), the sensor works correctly.
Method 2: Third-party annexes
If the engineering menu is not available, install one of the applications:
- 📱 CPU-Z — Shows the status of all sensors in the Sensors section.
- 🔍 Sensor Test – visually displays the sensor’s response to an obstacle.
- 🛠️ Phone Doctor Plus – Completes a full phone diagnosis.
Make sure there is no dirt or film on the sensor.|
Run the test through the engineering menu or app |
Check the sensor response by covering it with your hand.|
Compare the readings with reference (5). → 0 when obstructed)-->
Method 3: Manual test during a call
The easiest way to do this is to call another phone and watch the screen:
- Start the call.
- Hold the phone to your ear, the screen should go out.
- Take the phone away, the screen should turn on.
If the screen is unresponsive or chaotic, the problem is confirmed.
⚠️ Attention: In some firmware MIUI Auto-disable screen function during call is disabled by default. Check settings in Settings → System applications → Phone. → Incoming challenges → Smart blocker.
Calibration of the proximity sensor: step-by-step instructions
If the sensor is working but with delays or false positives, it can be recalibrated, especially after a screen change or firmware update.
For calibration:
- Install the Proximity Sensor Reset app from Google Play.
- Run it and follow the instructions on the screen.
- When the program asks, cover the sensor with your hand and wait for the signal.
- Remove your hand and complete the calibration.
Alternative method (without applications):
- Go to Settings → About Phone → MIUI version.
- Click on the line with the version 7-10 times to activate the developer mode.
- Back to Settings → Additionally. → For developers.
- Find the item Do not turn off the screen and turn it off (if it is active).
- Reboot the phone.
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Calibration of the sensor only helps in case of software failures, if the sensor is physically damaged (for example, after a fall), a replacement is required.
What to do if the proximity sensor is not working
If the diagnosis showed that the sensor is defective, act on the algorithm:
- Clean the sensor: Remove the protective glass/film (if any). Wipe the top frame with an alcohol wipe. Blow the sensor hole with compressed air (no strong pressure!).
- Update your firmware: Go to Settings → About Phone → System Update. Install the latest MIUI updates.
- Reset settings: Back up your data. Reset through Settings → Restore and Reset → Reset settings.
Contact the service.
- If the sensor does not respond to calibration and cleaning, a replacement will be required.
- The cost of repair in official Xiaomi services is from 800 to 1500 rubles (2026).