How to set up a proximity sensor on Xiaomi Redmi 9C: a complete guide with solutions to problems

What is a proximity sensor and why you need it in the Redmi 9C

The proximity sensor in the Xiaomi Redmi 9C smartphone is a small but critical component that is responsible for automatically turning off the screen during a phone call. When you bring the device to your ear, the sensor captures close distance and extinguishes the display, preventing accidental pressing and saving battery power. Without the correct operation of this sensor, you risk problems: the screen does not turn off when you call (which leads to the pressing of the buttons with your cheek), or, conversely, does not turn on again after the conversation is completed.

The Redmi 9C uses an infrared proximity sensor that is located next to the front camera, and its work is based on measuring the reflected signal: when an object (like your head) is close, the sensor detects changes in infrared intensity. Despite its simplicity, this module can fail due to software failures, contamination or mechanical damage. Next, we will discuss how to check its performance, adjust and fix typical problems.

It's important to understand that proximity sensor problems are often confused with display or firmware malfunctions, for example, if the screen doesn't respond to touch after a call, it might be due to the touch layer hanging, not the sensor, and to accurately diagnose the problem, you'll need to run several tests, and this section is about it.

How to check the proximity sensor on the Redmi 9C

Before you set up the sensor, make sure it works at all, and there are a number of ways to do that, from built-in MIUI tools to third-party applications, starting with the simplest method.

The Xiaomi Redmi 9C has a hidden test mode that allows you to check all sensors, including approximations.

1. Open the Phone app.
2. Enter the combination: ##6484### (or #4636## for the alternative menu).
3. Select the Hardware Testing option → Sensor Test.
4. Find the Proximity Sensor bar and cover the top of the screen with your hand.

If the sensor is in good condition, it will change from 5.0 cm (or similar) to 0.0 cm. If the numbers don't change, the sensor won't work. Also, pay attention to the screen response: in test mode, it should go out when the hand approaches.

Alternatively, third-party utilities like CPU-Z or Sensor Box (available on Google Play) can display data from all sensors in real time, and the advantage of this approach is that you can watch the sensor work in the dynamics, not just in the static test, but remember that if the sensor is not detected even in these applications, the problem is likely hardware (damaged by the plume or module).

Configure the proximity sensor through the MIUI menu

In most cases, the proximity sensor on the Redmi 9C does not require manual adjustment — it works out of the box. However, if you notice a failure (for example, the screen does not go out on a call or wakes up too long), you can try to adjust the settings through hidden settings.

Follow the instructions:

1. Open the Settings. → The phone.
2. Tap 5-7 times on the line MIUI version until the notification appears You became a developer!
3. Go back to the main Settings menu and select a new Developers item.
4. Scroll down to the Hardware Acceleration block and find the Debug Option of the Approach Sensor (or Proximity Sensor Calibration).
5. Activate it and follow the prompts on the screen (usually cover the sensor with your hand and wait for the calibration to be completed).

If you don't have the Debugging Option, it means your version of MIUI doesn't support manual calibration, and you have two options:

• 🔄 Reset sensor settings via the engineering menu (combination ##3644633##).
• 📱 Update the firmware to the latest version – sometimes bugs with sensors are fixed in new builds.
• 🛠️ Contact the service if the problem is hardware (for example, the train has gone away).

Make sure the screen is clean (no film or glass blocking the sensor)

Close all background applications

Connect the charger (the battery must be charged at least 50%)

Make a backup copy of important data-->

Typical problems of the proximity sensor and their solutions

Even after calibration, the proximity sensor on the Redmi 9C may not work properly, so let's look at the most common symptoms and how to treat them.

Special attention should be paid to safety glasses and covers. If they cover the area of the sensor (usually the top of the screen next to the camera), this can block the infrared signal. Try to remove the accessories and repeat the test. Also check if moisture has been hit by the glass, which is a common cause of false positives.

⚠️ Warning: If the sensor stopped working after the phone fell, don't try to disassemble the device yourself. 9C The loop of the proximity sensor is very thin and easily damaged by careless handling.

Reset sensor settings and firmware

If manual calibration doesn't work, the next step is to reset the sensors to the factory settings, which you can do through an engineering menu or a full phone reset, and let's look at both.

Method 1: Reset through the engineering menu

1. Enter the combination ##3644633##.
2. Select Proximity Sensor.
3. Press Reset Calibration (or similar option).
4. Reboot the phone.

Method 2: Complete reset (Hard Reset)

This method will delete all the data from the phone, so make a backup first.

1. Go to Settings → About the phone → Reset settings.
2. Select Reset all settings.
3. Confirm the action and wait for the process to be completed.

Once reset, the proximity sensor should be activated in normal mode, and if the problem persists, you just have to reflash the phone via Fastboot or Recovery.

• 📥 Download the official firmware for Redmi 9C Xiaomi.
• 🔧 Use the Mi Flash Tool to install via Fastboot.
• ⚠️ Make sure the firmware version matches the model (angelica for Redmi) 9C).

Alternative solutions: disabling the sensor and using third-party applications

If the proximity sensor is permanently out of order and repair is not possible, you can temporarily do without it.

1. Disconnect the sensor through settings

Some versions of MIUI have an option to force the proximity sensor to shut down.

1. Go to Settings. → For developers.
2. Find the option to turn off the proximity sensor (or Disable Proximity Sensor).
3. Activate it.

After that, the screen won't go out during calls, but you can manually block it with a power button.

Applications for sensor emulation

There are utilities in Google Play that replace the proximity sensor software, like Proximity Sensor Fix or Sensor Disabler, which are timer-based, and the screen goes out after a predetermined time, and the downside is delay and possible crashes.

⚠️ Warning: Disabling the proximity sensor can lead to increased battery consumption, as the screen will remain on during conversations, and it also reduces usability - you will have to constantly monitor for accidental presses.

Prevention of malfunctions of the proximity sensor

To make the proximity sensor on the Redmi 9C last longer, follow the simple recommendations:

• 🧼 Clean the sensor area regularly of dust and fat. Use a soft wipe and alcohol (non-aggressive solvents!).
• 📵 Avoid mechanical damage. Don't drop your phone or press the top of the screen.
• 💧 Protect yourself from moisture. Even a small ingestion of water can cause the sensor's contacts to corrosion.
• 🔄 Update the firmware. In new versions. MIUI Often fix sensor bugs.
• 🛡️ Use quality accessories. Cheap glass and covers can block the sensor signal.

Critical information: In the Redmi 9C, the proximity sensor is located under the display glass, so replacing it requires a complete disassembly of the phone and replacing the entire camera / sensor module. Self-repair without experience can damage the plume or screen matrix.

If you notice that the sensor started to crash after installing custom firmware, try returning to the official version of MIUI. Some custom builds (for example, LineageOS) may not work properly with Xiaomi hardware components.

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Before cleaning the sensor, turn off the phone and let it cool. Heating from prolonged operation can distort the readings of the infrared sensor.

FAQ: Frequent questions about the Redmi 9C proximity sensor