Xiaomi Redmi 9 is one of the most popular budget smartphones, but even in such devices, there can be problems with sensors. The proximity sensor is responsible for turning off the screen during a conversation, preventing accidental pressing of the cheek or ear. If it fails, the phone ceases to respond to the approach to the ear, the screen does not go out, and the battery is discharged faster due to constant backlighting.
In this article, you will find the exact location of the proximity sensor on the Redmi 9 (including the Redmi 9A/9C/9T modifications), how to diagnose it without disassembling the phone, and how to fix typical malfunctions.
Where exactly is the proximity sensor on Xiaomi Redmi 9
The proximity sensor in Redmi 9 is built into the top of the display module, next to the front camera and speaker.
- 📍 Right of the speaker (if you look at the phone screen facing you).
- 🔍 Under the protective glass, in the zone of the black frame (the so-called "frontal" space).
- 📱 At the level of 1-1.5 cm from the upper edge of the screen - it is there that the infrared emitter and photoreceiver are located.
It's important to understand that the proximity sensor is not a single chip, but a pair of elements: an IR emitter (send) and an IR receiver (receive), which work in pairs: the emitter sends an invisible beam, and the receiver detects its reflection from an obstacle (for example, an ear during a call). If at least one of the elements is damaged, the sensor ceases to function.
What does the sensor look like under a microscope
On some Redmi 9 modifications (e.g. Redmi 9T), the sensor can be shifted closer to the center of the upper frame. To accurately determine its position, shine a flashlight at an angle on the screen off - you will see two barely noticeable holes (they are smaller than the hole in the front camera).
How to check the performance of the sensor without disassembly
Before you bring your phone to the service, make sure the sensor is the problem. Here are 3 ways to diagnose:
- Test through the engineering menu: Enter the code ##6484## in the Phone app → select Proximity Sensor. Put your hand to the top of the screen - the value should change from 5.0 cm to 0.0 cm. If the numbers do not change, the sensor is faulty.
- Call another phone and move Redmi 9 to your ear. The screen should go out in 1-2 seconds. If it stays on, the problem is confirmed.
- Application usage: Install the Sensor Test utility (available on Google Play) and check the sensor response in real time.
If the sensor does not respond to any of the tests, the reasons may be as follows:
- 🔧 Mechanical damage (glass crack, impact, moisture intrusion).
- 📱 Detachment of the plume after replacing the display or glass.
- 🔄 Firmware failure (especially after update) MIUI).
- 🧲 Effect of magnetic interference (e.g. from a magnet case).
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If the sensor is delayed, try calibrating it: go to Settings → About Phone → MIUI version and press 5 times on "Core". In the menu that opens, select Proximity Calibration.
Why the sensor stops working after changing the glass or display
One of the most common reasons for the Redmi 9's proximity sensor to fail is that it's not a good display replacement, because it's soldered into a flexible plume of the screen, and it's easy to damage when it's disassembled.
- 🔨 Overheating of the plume during puffing - leads to detachment of the sensor contacts.
- 🧴 The hit of glue on the IR emitter or receiver (they become opaque to infrared light).
- 📏 Incompatible display – cheap Chinese modules sensor may not be at all.
On the Redmi 9, the proximity sensor is not a separate part, it is built into the display module. This means that when it breaks, you need to replace the entire screen, not just the sensor. The exception is the detachment of the plume, which can be eliminated by soldering (but this is a temporary solution).
☑️ What to check after replacing the display
If you replace the glass instead of the entire display, the problem may be that the protective film is not properly installed, for example, if the film has a metallized layer or is too thick, it blocks the IR signal. Try temporarily removing it and repeating the test.
Program causes of sensor malfunction
Sometimes the proximity sensor stops working because of software failures. Here are the typical scenarios:
| Reason. | Signs. | Decision |
|---|---|---|
| Failure after MIUI update | The sensor worked, but stopped after the update. | Remove the firmware or reset the settings |
| Conflict with the annex | The problem arises after installing new software | Remove suspicious programs in safe mode |
| Wrong settings | The screen doesn't go out, but the sensor reacts in tests | Check the call settings in Settings → Calls |
| Viral SO | Spontaneous pressing, advertising, brakes | Scan your phone with an antivirus (such as Malwarebytes) |
To eliminate software malfunction:
- Restart your phone in Safe Mode (press the power button → “Reboot Safe Mode”). If the sensor is running, the third-party app is to blame.
- Reset to factory settings (Settings → Additional → Reset). Attention: pre-backup data!
- Flick the phone through the Mi Flash Tool (instructions for Redmi 9 are available on the official Xiaomi website).
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If the sensor works in the engineering menu, but does not work during the call - the problem is in the MIUI settings, not in the hardware.
How to temporarily bypass the malfunction of the approach sensor
If the sensor is broken and repairs are delayed, you can use temporary solutions to keep the phone comfortable to use:
- 📱 Turn off the power button screen: during the call, just press the lock button to extinguish the backlight.
- 🔄 Headset usage: connect wireless or wired headphones – the screen won’t interfere.
- 🤖 Simulator applications: for example, Proximity Sensor Fix (emulates the operation of the sensor through a gyroscope).
- 📲 Setting up the auto turn: in Settings → Screen. → Turn off the function so that the screen does not rotate accidentally.
One of the most reliable solutions is to install an alternative firmware (like LineageOS), where you can manually adjust the sensitivity of the sensor or turn off the sensor check, but this requires unlocking the bootloader and fastboot skills.
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If you make frequent calls, install the Quick Settings widget on the main screen with a lock button, which will allow you to extinguish the backlight with one touch.
Remember, temporary solutions don't fix the cause of the failure, because if the sensor is physically damaged, it will need to be replaced or repaired sooner or later.
Cost and complexity of approximation sensor repair
Repair of the proximity sensor on Redmi 9 depends on the cause of the malfunction.
| Type of repair | Cost (₽) | Time. | Difficulty |
|---|---|---|---|
| Cleaning the sensor contacts | 500–1 000 | 30–60 minutes | Low. |
| Replacement of the display plume | 1 500–2 500 | 1-2 hours | Medium |
| Replacement of the display module | 3 000–5 000 | 2-3 hours | Tall. |
| Sensor soldering (if detached) | 2 000–3 500 | 1-2 days | Very high. |
The cheapest option is to clean the contacts, but it only works if the problem is oxidation or dust, and if the sensor is physically damaged, you'll need to replace the display, because it's not sold separately.
Should I repair it? Depends on the condition of the phone.
- ✅ Repair is justified if the rest of the components are in good working order and the phone is used as the main one.
- ❌ It is not advisable if there are other serious breakdowns (for example, a faulty battery or motherboard).
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On AliExpress you can find display modules for Redmi 9 at a price of 2 000 ₽, But the risk of running into a non-original part with a broken sensor is very high.
Frequent questions about the proximity sensor on Xiaomi Redmi 9
Can I turn off the proximity sensor if it doesn’t work?
Why does the sensor go off on its own (the screen goes off for no reason)?
Can I replace the proximity sensor myself?
Does the cover affect the approach sensor?
Which Redmi 9 models have the same proximity sensor?
If your Xiaomi Redmi 9 stopped extinguishing the screen during a call, take it easy to carry it to the service. In most cases, the problem is solved by software or by cleaning contacts. However, if the sensor is physically damaged, you will need to replace the display module - in this case, evaluate the feasibility of repair based on the condition of the phone.
Remember, proximity sensors are not only convenient, they're also safe, and without them, the risk of random taps during a conversation increases, and the battery runs out faster, and if self-diagnosis doesn't work, you can get good feedback from the specialists, and that will save you time and nerves.