Where is the proximity sensor in Xiaomi Redmi 9C: location, function and diagnosis

Introduction: why you need a sensor approach in a smartphone

Approximate sensor in Xiaomi Redmi 9C — It's a small but critical component that makes the phone comfortable when you make calls, and without it, the screen won't automatically shut down when you bring the device to your ear, causing accidental taps, disconnection, or even voice activation. Despite the simplicity of the design, this sensor often becomes a source of problems: from banal contamination to hardware breakdowns.

Many Redmi users 9C When you're faced with a screen that doesn't go out during a conversation or doesn't turn on after a call is over, it's the proximity sensor that's responsible for 80 percent of the time, either software failure or physical damage. But before you carry the phone to the service center, it is worthwhile to figure out where this sensor is located, how it works and whether it is possible to restore its functionality on your own.

In this article, we will analyze in detail: where exactly is the proximity sensor in Xiaomi Redmi 9C, How to check it without special tools, typical malfunctions and how to fix them, and you will learn why this sensor can fail after a phone drop or a firmware update, and what to do about it.

Where is the proximity sensor in Xiaomi Redmi 9C: positioning

At Xiaomi Redmi 9C The proximity sensor is integrated into the top of the display module, next to the front camera and speaker, specifically located under the screen glass, to the right of the auditory speaker (when you look at the phone in the standard position). It is not visible visually – it is hidden under a black masking film, but its position can be determined by a small hole or a transparent point on the screen frame.

To get a better idea of where to look: pick up your phone, look at the top of the screen (where the front camera is located). To the right of the speaker, you'll see two small holes or transparent spots -- this is the proximity sensor and the light sensor, the proximity sensor is usually closer to the edge, and the light sensor is slightly to the left.

It is important to understand that Redmi 9C It uses an infrared proximity sensor rather than a capacitive one (as in some flagship models), which means it is sensitive to contamination on glass, protective films or covers that can block the IR signal.

Photo of sensor location

Below is the top panel diagram of Xiaomi Redmi 9C sensory:

⚠️ Warning: If your phone has a protective film or glass with an opaque coating in the sensor area, it may block the sensors from working.

How the proximity sensor works in Redmi 9C: principle

Approximate sensor in Xiaomi Redmi 9C It's basically an infrared light, and it's made up of two basic elements: an IR emitter (LED) and an IR receiver (photodiode), and when you hold your phone to your ear, the emitter sends an invisible signal that bounces off the surface (your skin) and goes back to the receiver. The system analyzes the delay time and the strength of the reflected signal, and then turns off the screen.

The whole process takes a fraction of a second and happens completely automatically. 9C can be divided into several stages:

• 📱 Approximation detection: When an object (like your ear) is 2-5 cm away from the sensor, the IR signal is reflected and recorded by the receiver.
• 🔄 Signal processing: The phone's microcontroller analyzes the data and sends a command to turn off the screen and touch layer.
• 📵 Screen lock: The display goes out and the sensor stops responding to touches to prevent accidental taps.
• 🔙 Resume: When you pull the phone away from your ear, the sensor detects the absence of the reflected signal and turns the screen on again.

I wonder what Redmi is. 9C proximity sensor is set to operate at a distance ~This means that the screen will go out not only when you put the phone to your ear, but also if you simply cover the top with your palm (for example, when reading a message on a bright sunny day).

How to check the proximity sensor on Xiaomi Redmi 9C: 3 ways

If you suspect that the proximity sensor is not working properly (the screen does not go out during the call or does not turn on after the call), you can check it yourself. Here are three reliable methods that do not require disassembling the phone or special tools.

1. Check through the engineering menu (code ##6484##)

The most accurate way to diagnose is to use a hidden engineering menu.

1. Open the Phone app.
2. Enter the combination: ##6484## (some firmware may not work – see the alternative below).
3. Select Proximity Sensor (Proximity Sensor).
4. Put your hand to the top of the screen, and the value should change from 5 (no object) to 0 (object detected).

If the values don't change or the menu doesn't open, try the alternative code: ##4636## → Phone information → Check the sensor response in real time.

2. Checking by application

If the engineering menu is not available, install one of the specialized applications for testing sensors, for example: «CPU-Z», «Sensor Test, or "Phone Doctor Plus," these tools show the status of all sensors in real time, including the proximity sensor.

On the Phone Doctor Plus app:

1. Run a sensor test.
2. Find the Proximity Sensor section.
3. Put your hand to the top of the phone – the status should change from Far (far) to Near (close).

3.Manual check during call

The simplest, but less accurate method is:

1. Call another phone or activate a voice call.
2. Bring the Redmi. 9C The screen should go out in 1-2 seconds.
3. Take the phone away, the screen should turn on again.

If the screen is not responding, the problem may be:

• 📱 Sensor pollution (dust, fat, protective film).
• 🔧 Software failure (needs resetting or flashing).
• 🔨 Hardware failure (damage to the plume or the sensor itself).

Typical malfunctions of the proximity sensor in Redmi 9C and their causes

Approximate sensor in Xiaomi Redmi 9C It can fail for a number of reasons, from simple pollution to serious hardware failures.

1.The screen doesn't go out during the call

If the display remains active when you hold the phone to your ear, it could mean:

• 🧴 Sensor pollution: Dust, sweat, or residues of adhesive from the protective film block the IR signal. The solution is to clean it neatly with an alcohol tampon.
• 📲 Firmware problems: After the update MIUI The sensor may not work properly, so it helps to reset or roll back to the old version of the software.
• 🔌 Train damage: If the phone fell or was subjected to mechanical stress, the flexible plume connecting the sensor to the motherboard could be damaged.

2.The screen does not turn on after the call is completed

The reverse is that the display is turned off even when you're moving the phone away from your ear.

• 🔄 Sensor freeze: System glitch, in which the sensor "stuck" in the Near state. Helps reset or forced shutdown of the screen with the power button.
• 🔋 Weak battery: With low battery charge (<15%) The system may not be processing sensor signals correctly. Charge the phone and check again.
• 🛠️ Chip failure: Rarely, the sensor controller on the motherboard fails.

3. The sensor is acting arbitrarily.

If the screen goes out for no reason (such as when you just hold the phone in your hand), the problem may lie in:

• 📊 Miscalibration: After changing the screen or firmware, the sensor may need to be reconfigured.In the engineering menu (#6484###), try resetting the settings.
• 🌡️ Temperature exposure: When the phone overheats or cools, the IR sensor can give false positives.
• 📱 Case conflict: Some high-sided cases can close the sensor, mimicking the approach of an object.

⚠️ Warning: If the sensor stopped working after a phone drop or moisture hit, don't try to disassemble the device yourself. 9C the sensor is soldered to the flexible plume of the display, and its replacement requires special equipment.

How to fix the proximity sensor in Xiaomi Redmi 9C: step-by-step

If your diagnosis shows that the proximity sensor is not working properly, try the following recovery methods: Start with the simplest methods and move on to more complex ones only if the previous ones did not help.

1. Cleaning the sensor from contamination

Most often, the problem is the banal dust or the greasy prints on the glass, to clean the sensor:

1. Turn off the phone.
2. Take a cotton swab dipped in isopropyl alcohol (at least 70%).
3. Gently wipe the area around the front camera and speaker, paying special attention to the right edge (where the sensor is located).
4. Let the phone dry 5-10 minutes before turning on.

Do not use abrasive materials (glass wipes, paper towels) – they can scratch the protective coating of the sensor.

2. reset sensor settings through the engineering menu

If the sensor fails after updating the firmware, it can be recalibrated:

1. Open the engineering menu with the code ##6484##.
2. Select Proximity Sensor.
3. Press Calibrate or Reset (Reset).
4. Hold and move your hand away from the sensor several times for testing.

If the menu is not available, try an alternative method:

1. Go to Settings → System → Resetting settings.
2. Select Reset App Settings (not a full reset!).
3. After restarting, check the sensor.

3. Update or roll back firmware

Sometimes bugs in MIUI They cause the sensors to malfunction:

• 📱 Update the firmware: Go to Settings → The phone. → Update the system and install the latest version MIUI.
• 🔙 Reverse to the old version: If the problem appeared after the update, download the previous firmware from the Xiaomi Firmware website and thread it through Fastboot.

⚠️ Note: When you roll back the firmware via Fastboot, all data on the phone will be deleted. Pre-backup through Settings → Additionally. → Backup and reset.

Replacement of sensor or plume (for experienced users)

If all the software methods are exhausted and the sensor is still down, all that remains is hardware repair. 9C The approach sensor is soldered into a flexible plume of the display module, so it is impossible to replace it separately - you will have to change the entire plume or screen.

The replacement will require:

• 🔧 Set of screwdrivers (cross, plastic blades).
• 🔥 Hazel for softening glue (temperature) ~60°C).
• 📱 New display module with a plume (cost) ~1500–2500 ₽).

Instructions for replacement:

1. Turn off the phone and remove it. SIM-map.
2. Heat the screen edge with a hair dryer to soften the glue.
3. Carefully tuck the screen with a plastic spatula, starting at the bottom edge.
4. Disconnect the display plume from the motherboard.
5. Install a new module and assemble the phone in reverse order.

💡

If you are not sure of your abilities, it is better to contact the service center.The cost of replacing the plume in the official Xiaomi service is ~2000–3000 ₽, But you'll get a job guarantee.

Frequent questions about the proximity sensor in Xiaomi Redmi 9C

💡

If the proximity sensor in Redmi 9C stopped working after mechanical impact (fall, impact), in 90% of cases, you will need to replace the plume or display module.

Conclusion: when to contact the service

Approximate sensor in Xiaomi Redmi 9C — It's a small but important element that makes the phone comfortable, and most of the time, it's caused by contamination, software failures, or failed upgrades that you can fix yourself. However, there are situations where without the help of specialists can not do:

• 🔧 Mechanical damage: If the phone fell, got wet or was subjected to severe vibrations, the plume or the sensor itself could be damaged.
• 🔥 Moisture: Even after the plume contacts have completely dried, corrosion can disrupt the sensor.
• 📵 Complete lack of response: If the sensor does not respond to either calibration or resetting, it is likely to have failed physically.

The cost of repair in the official service Xiaomi starts from 1500 ₽ (plume replacement) and up to 4,000 ₽ (Full replacement of the display module if your Redmi 9C For more guarantees, contact an authorized service center - repairs can be free of charge.

Remember: replacing a screen or plume without experience can damage other components (for example, a fingerprint sensor or a front camera).