Why the screen on Xiaomi Redmi 9T does not go out during the call – a complete analysis of the problem

Introduction: Why this is an important issue

You call the Xiaomi Redmi 9T, you hold the phone to your ear, and the screen continues to glow, react to touch and accidentally press buttons. The sound switches to speaker, the conversation is interrupted, and the battery goes down many times faster. Familiar situation? This malfunction is not only annoying, but also creates real inconveniences, from accidental presses to leakage of confidential information (for example, if the screen unlocks during the call).

In 80 percent of cases, the problem is with the proximity sensor, a small sensor next to the front camera that should turn off the display when you hold the phone to your ear, but software failures, mechanical damage, and even incorrect settings can be to blame. In this article, we will analyze all possible causes, from the simplest to the most complex, and give clear instructions for eliminating each.

1. Approximation Sensor: How It Works and Why It Breaks

The proximity sensor in Redmi 9T is an infrared sensor that measures the distance to an object (in this case, your ear). When you hold the phone to your head, the sensor sends a signal to the system, and the screen goes out, and if it's faulty or locked, the display stays active.

Causes of sensor failure:

• 🔍 Sensor contamination: Dust, greasy skin marks, or protective film can block infrared signal.
• 💥 Mechanical damage: Falling a phone, especially on a screen, can displace or damage the sensor.
• 🖥️ Software failure: after the update MIUI or resetting the sensor may not work properly.
• 🔋 Power shortage: If the battery is under 15%, the system sometimes ignores sensor signals to save energy.

To test the sensor's performance, run a test in the engineering menu (instruction below) If the sensor doesn't respond at all, it's a hardware problem. If it responds but is delayed or unstable, it's the software or the contamination.

2.How to check the proximity sensor on the Redmi 9T

Before you disassemble the phone or reset the settings, make sure the sensor doesn't really work.

1. Open the Phone app and dial the code: ##6484## (or #4636## → "Equipment Testing").
2. Select Proximity Sensor (Proximity Sensor).
3. Close the sensor with your hand (or hold the phone to your ear). The screen should show a value of 0 (or Covered). Remove your hand, the value should change to 5 (or Uncovered).

If the values don't change or the response is more than 2 seconds late, the sensor is faulty. If the test is successful, but the screen still doesn't go out when you call, the problem is settings or firmware.

⚠️ Attention: If the sensor shows 0 after the test, even when the hand is removed, this is a sign of hardware failure. Self-repair is possible only if you have experience with soldering equipment.

3. Software glitches: resetting settings and updating MIUI

If the sensor is working, but the screen is not going out, the software is to blame.

• 📱 Gluck MIUI: after updating or installing custom firmware, sensor settings can fly.
• 🧹 Application conflict: Some programs (such as launchers or optimizers) block sensors.
• 🔄 Cache system: clogged cache can interfere with the correct operation of sensors.

Try these steps in order:

1. Clear the system cache: Settings → About phone → Memory → Clear the cache Reboot the phone and check the sensor.
2. Reset the settings of the phone application: Settings → Annexes → Application management → Phone. → Warehouse → Clear the data ⚠️ Warning: This will remove the call history!
3. Update MIUI to the latest version: Settings → About Phone → System Update If an update is available – install it and restart the phone.
4. Perform a factory reset (if nothing worked): Settings → Additional → Restore and Reset → Reset Before reset, be sure to back up your data via Settings → About Phone → Backup – otherwise you’ll lose photos, contacts and messages.

Save contacts in Google Account|

Copy photos to a computer or cloud|

Write down passwords from Wi-Fi and apps |

Make sure the battery is over 50 times charged%-->

4 Mechanical damage: what breaks and how to repair

If the sensor doesn't respond to the tests, and the software methods didn't help, the problem is the hardware. 9T most often:

If you don't have experience in electronics repair, don't try to disassemble the Redmi 9T yourself.

• 🔧 Fragile battery plume – easy to break with careless removal.
• 🔥 Adhesive tape under the battery – if it is not properly removed, you can damage the board.
• 📱 Sensor of approaching soldered to the motherboard - to replace you need a soldering hair dryer.

It is better to contact the Xiaomi service center or a proven workshop. The average cost of diagnosis is 300-500. ₽, repairs - from 800 ₽.

💡

Before visiting the service, take a picture of the IMEI phone (type *#06#) and save the purchase check - this will speed up the repair process under warranty.

5. Settings and third-party applications: hidden causes

Sometimes the screen doesn't go out because of incorrect settings or software conflicts.

1. In your pocket mode: If you have Settings mode on → Lock screen → In your pocket mode, your phone may ignore the proximity sensor. Turn off this option and check the calls.
2. Special Options Settings: Go to Settings → Special facilities → System settings and make sure you are disabled: 👁️ Keeping the screen on 🔄 Autoturn when blocking 📱 Ignore sensors (if any)

Call management applications

Software like Truecaller, Call Recorder, or DualSpace can block the sensor.

Settings → Applications → Permissions → Microphone / Phone

Revoke permissions from suspicious apps and reboot your phone.

If the problem occurs after installing a new launcher (such as a Nova Launcher or POCO Launcher), return the standard MIUI launcher:

Settings → Applications → By default → Launcher

6. Alternative solutions: if nothing has worked

If all methods have been tried and the screen still goes out, radical measures remain:

• 🔄 Fastboot Reflash: Complete Reinstallation MIUI The Mi Flash Tool can restore the sensor to work.Instructions: Download the official firmware for Redmi 9T (Lime model code from Xiaomi. Unpack the archive and launch the Mi Flash Tool. Connect the phone in Fastboot mode. + Power. Select a firmware file and press Flash. ⚠️ Warning: Wrong firmware can turn your phone into a brick. Use only official files for your model!
• 🛠️ Disabling the sensor software: If the sensor is broken and repair is impossible, you can turn off its response to calls through the ADB: adb shell settings put global proximity_delay 2500 This command will make the screen go out through 2.5 seconds after the call starts, regardless of the sensor. ADB You need Platform Tools and enabled debugging USB.
• 📱 Use of headset: Connect wireless headphones (such as Xiaomi AirDots) – when talking through them, the screen will lock automatically, even if the sensor does not work.