The Xiaomi Redmi 9A is one of the most popular budget smartphones, but even in such devices, sometimes there are problems with sensors. The proximity sensor is responsible for turning off the screen during a conversation, preventing accidental tapping of the cheek or ear. If it fails, this leads to inconvenience: the screen does not go out when you call, or vice versa – does not turn on after the call is completed.
In this article, we will take a look at exactly where the proximity sensor in the Redmi 9A is located, how it looks on the board and on the front of the case, and what signs indicate that it is malfunctioning, and how to check the sensor itself and what to do if it ceases to function.
Where is the proximity sensor in Xiaomi Redmi 9A: the exact coordinates
In Redmi 9A, the proximity sensor is integrated into the top of the display module, next to the light sensor and the front camera, and physically it is a miniature infrared sensor that is hidden under the screen glass. You can't see it from the outside, just a small hole for the IR signal to pass through.
If you look at the front panel of the smartphone, the proximity sensor is located to the right of the front camera (if you hold the phone vertically, the screen to yourself), its exact position can be determined by a barely noticeable point on the black frame of the display — usually it is at a distance of ~ 5 mm from the camera.
- 📍 Above: under the display glass, in the upper frame.
- 🔍 Left/right: Right of the front camera (when looking at the screen).
- 🛠️ On the board: soldered to the motherboard under the display, next to the connector of the screen plume.
The photos of the disassembled Redmi 9A show that the sensor is a small black chip marked with a small black chip connected to the board through thin contacts, which is easy to confuse with the light sensor, but the latter is usually larger and located to the left.
How does the proximity sensor look on the board and in the case of the smartphone
To better understand where to look for a sensor, consider its visual features:
- 📱 On the front side: a small black dot (diameter) is visible under the screen glass ~1 mm) to the right of the camera. Sometimes it's hard to see without zooming in.
- 🔧 On the board: it's a chip size. ~2×2 mm with a symbol (e.g, APDS-9930 Or similar. Located with a display plume.
- 🔦 Under the microscope: you can see the IR emitter and the photodiode, which work in pair to determine the distance to the object.
On the Redmi 9A board, the proximity sensor is often located next to:
- 📶 Antenna contacts (top of the fee).
- 🔋 Battery connector (left or lower).
- 📷 Front camera plume.
| Element | Location relative to the sensor | How to tell |
|---|---|---|
| Light sensor. | Left (~3-5 mm) | Larger, often with a white filter |
| Front camera. | Left (~1 cm) | Round hole with lens |
| Dynamic (conversational) | Below (~1-2 cm) | A rectangular grille with holes |
| Display plume | Under the sensor (on the board) | Flexible flat cable |
Importantly, on some Redmi 9A variants (e.g. in the Indian market), the proximity sensor can be shifted closer to the center of the upper frame, due to differences in board layout.
Signs of malfunction of the proximity sensor
If the proximity sensor fails, this is manifested by the following symptoms:
- 📵 The screen does not go out during the call – remains active, which leads to accidental pressing.
- 🔄 The screen does not turn on after the call is completed - you have to press the power button.
- 🔦 Unintentional switching on/off of lighting when talking.
- 🛠️ Errors in sensor tests (code ##4636##* or engineering menu).
Most often, problems arise due to:
- 💧 Moisture entering glass (oxidation of contacts).
- 🔨 Mechanical damage after falling.
- 🔋 Firmware failure (especially after unofficial updates).
- 🧲 Effects of strong magnetic fields.
What if the sensor is not working properly after the MIUI update?
⚠️ Note: If the screen doesn’t go out only in certain apps (like WhatsApp or Telegram), the problem may be the settings of the messengers themselves, not the sensor.
How to check the proximity sensor on Xiaomi Redmi 9A
There are several ways to diagnose:
- Visual test: Call your phone or dial a number. Put your hand up to the top of the screen (where the sensor is located). If the screen goes out, the sensor works. If not, you need diagnostics.
- Enter the code ##4636##. Select Hardware Testing → Sensors. Find the Proximity Sensor string and check for your hand's response.
With the help of applications:
- Install CPU-Z or Sensor Test from Google Play.
- Run a sensor test and monitor Proximity's readings.
After the shutdown, the screen will not go out when talking.
Why does the sensor work too late or too early?
How much does it cost to replace the proximity sensor in the service?
Can I use my phone without a proximity sensor?
How to protect the sensor from failures?
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If the proximity sensor stopped working after the phone fell, most likely the display plume or the board itself is damaged. In this case, self-repair is not recommended - contact the service.