Why the screen dims on Xiaomi Redmi when you call and does not light up – a full analysis of the problem

You call the phone, you bring the Xiaomi Redmi to your ear, and the screen suddenly goes out, without responding to touch. The call goes, the person hears you, but you can only bring the display back to life by rebooting or accidentally pressing buttons. A familiar situation? This problem is found on models from the Redmi Note 8 Pro to the Redmi 12, and its causes lie in both system settings and hardware malfunctions.

In 80% of cases, the proximity sensor is to blame, blocking the screen during a conversation to avoid accidental taps. But if the sensor is not working properly, the screen can remain black even after the phone is taken away from the ear. Less commonly, the problem is associated with firmware, damaged display plume or even mechanical damage after a fall. In this article, we will analyze all possible causes, from the simplest (which you can fix yourself) to those that require the intervention of the service center.

Important: If the screen not only goes out, but also completely shuts down (bell interrupted, phone rebooted), this may indicate critical firmware errors or battery problems.

1. The proximity sensor: how it works and why it fails

The proximity sensor is a small infrared sensor next to the front camera, and its task is to detect when the phone is near the ear and turn off the screen to:

• 🔋 Save battery power (display is one of the main consumers of energy).
• 👆 Prevent accidental tapping of the cheek or ear (such as turning off a call or dialing a number).
• 📞 Improve communication quality (some models reduce signal power when approaching the head).

If the sensor is contaminated, damaged, or miscalibrated, it can stick in the earphone state, even when you've finished the conversation. On Xiaomi Redmi, it's like this:

• 📱 The screen goes out when you call and does not turn on until you press the power button.
• 🔄 After the call is completed, the display is not automatically restored.
• 🤳 The front camera may stop working (the sensor and camera are often combined in a single module).

You can check the sensor using an engineering menu or special applications (for example, the Sensor Test from Google Play), if the sensor values do not change when you approach the hand or remain at the level "1" (activated), then it is defective.

⚠️ Attention: Do not try to clean the sensor with alcohol or sharp objects! Infrared sensor is easily damaged. Use dry soft brush or compressed air to clean.

2. Software failures: firmware, settings and "glitches" MIUI

If the proximity sensor is working, but the screen is still dimming, the problem may be in the MIUI firmware or settings conflict, most often after:

• 📲 System updates (especially in beta versions) MIUI).
• 🔄 Resetting to factory settings.
• 🛠️ Installation of custom firmware or root rights.

The first thing to check is the proximity sensor settings in MIUI.

1. Open the Settings. → System system → Additionally.
2. Select the Approximation Sensor (on some versions of MIUI, the path may differ: Settings → Screen → Approximation Sensor).
3. Make sure that the Disconnect screen when approaching is enabled. If it is turned off but the problem persists, turn on and restart the phone.

If the settings don't work, try recalibrating the sensor.

1. Type the code ##6484## (not available on all models)
2. In the menu that opens, select Proximity Sensor and follow the instructions on the screen.
3. If the code doesn’t work, use the Mi Secret Codes app from Google Play.

If the reset didn't work, it could be a damaged firmware, and then it would help:

• 🔄 Retracement to the previous version MIUI (If the problem occurs after the update).
• 📥 Clean firmware installation via Fastboot (instruction below).

Mechanical damage: plume, display, body

If the software methods didn't work, the problem could be hardware, and it's often the fault of:

• 🔌 Damaged display plume (especially if the phone fell or disassembled).
• 📱 Cracks on the screen near the proximity sensor.
• 💧 Moisture falling under the body (even if the phone did not sink, condensate can oxidize the contacts).

How to check:

1. External inspection: Light a flashlight on the top of the screen (near the speaker) and if you see cracks or glass detachment, the sensor may have been damaged.
2. Flexibility test: Bend your phone carefully (not much!) If it flashes or artifacts appear, the problem is the plume.
3. Check after the fall: If the phone fell, even from a low height, the plume could move away from the connector on the motherboard.

If you suspect a hardware malfunction but are not sure, try a temporary solution:

• 🔧 Carefully tap on the top of the phone (where the sensor is located.
• 🔥 Heat your phone with a hairdryer (not much!) – this can temporarily eliminate contact oxidation.

⚠️ Warning: If after a drop, the screen not only goes out when you call, but also colored stripes or flickering appear, do not try to repair the phone yourself! these are signs of damage to the matrix or graphics chip, and any manipulations can aggravate the problem.

Clean MIUI installation: when necessary

If all the previous methods didn't work, and the problem is clearly software, then there's a clean firmware installation, which is a radical method, but it helps in 90% of cases where the fault is a curved firmware or a conflict of system files.

You'll need:

• 🖥️ Computer with Mi Flash Tool installed.
• 📥 Official firmware for your model (download only from the official Xiaomi website).
• 🔌 Cable USB (preferably original).

Step-by-step:

1. Download the firmware in.tgz format and unpack it.
2. Turn off your phone and press the Power button + Volume down to enter Fastboot mode.
3. Connect your phone to your PC and start the Mi Flash Tool.
4. In the program, select the unpacked firmware and press Refresh to detect the device.
5. Press Flash and wait for the process to complete (5-10 minutes).

After flashing, the phone will go back to factory settings, and if there was a software failure, the screen will stop going out when you call.

5. Alternative solutions: Sensor shutdown and workarounds

If you need to use your phone right away and repairs or firmware are temporarily unavailable, you can turn off the proximity sensor completely, and the downside is that the screen won't lock during the call, which can lead to accidental taps.

How to turn off the sensor:

1. Install the Disable Proximity Sensor app from Google Play.
2. Start it and activate the Disable Proximity Sensor option.
3. Reboot the phone.

You can also use the developer mode to turn off the sensor:

1. Activate Developer Mode: Settings → About Phone → MIUI version (click 7 times).
2. Back to Settings → Additionally. → For developers.
3. Find the option to Disable the proximity sensor and activate it.

If the sensor is turned off, but the screen is still going out, try using headphones for calls, in which case the proximity sensor does not activate, and the problem will not appear.

💡

If you make frequent calls with headphones, turn on the option to automatically respond when you connect your headphones in MIUI settings (path: Settings → System → Additional → Autoresponse) and this will eliminate the need to take the phone out of your pocket.

6. when you can not do without a service center

If none of these methods worked, the problem is likely hardware.

• 🔧 Display plume damaged (this can be seen from artifacts when bending the phone).
• 💧 Oxidized contacts after moisture is ingested.
• 🔨 Cracked glass over the proximity sensor.
• 🔋 The motherboard is faulty (for example, after a heavy impact).

The cost of repair depends on the model and type of malfunction:

Before the service visit:

• 📋 Backup your data (if the phone is still on).
• 🔍 Check whether the service uses original spare parts (on Xiaomi Redmi often put unoriginal plumes that quickly fail).
• 💰 Compare the cost of repairs to the price of a new phone (for example, for Redmi 8, replacing the display can cost half the cost of the device).

⚠️ Warning: If you're asked to replace the entire display unit instead of a plume or sensor, explain why. Sometimes, unscrupulous services impose unnecessary work. Ask to show the damaged element.

💡

If the phone is warranty, don't disassemble it yourself! The warranty is canceled when you open the case.

7 Prevention: How to avoid problems in the future

To avoid recurring problems, follow these guidelines:

• 📱 Use a cover with screen protection – this will reduce the risk of sensor damage when falling.
• 🚫 Do not place your phone down on hard surfaces (especially if it already has cracks).
• 🔄 Update regularly MIUI, Do not install beta unless you are ready for bugs.
• 💧 Avoid moisture – even a little humidity can oxidize the sensor contacts.
• 🔧 Don’t disassemble your phone without experience – Xiaomi Redmi plumes are very fragile.

If you often experience proximity sensor issues, consider buying a phone with an ultrasonic sensor (like the Xiaomi 13 or later).

It is also useful to periodically check the sensors with applications like Phone Doctor Plus or Sensor Test, which will help to identify the problem at an early stage.

FAQ: Frequent questions about the problem