How to turn on and configure the proximity sensor on Xiaomi Redmi 9T: instructions with a photo

The proximity sensor on the Xiaomi Redmi 9T is a small but critical element that is responsible for turning off the screen during phone calls. If it does not work, you risk accidentally pressing buttons with your cheek or ear, interrupting a conversation or activating loud communication. In most cases, the problem is solved software-based enough to turn on the sensor in the settings or recalibrate it.

In this article, we’ll look at all the ways to activate the proximity sensor on the Redmi 9T, including hidden diagnostic menus, resetting settings and hardware checks. You’ll also learn why the sensor can spontaneously shut down and how to avoid it. The instructions are suitable for all MIUI versions (including MIUI 12/13/14), but with the Redmi 9T firmware (codenamed lime).

What is a proximity sensor and why you need it

The proximity sensor is an infrared sensor located next to the front camera Xiaomi Redmi 9T. It detects when an object is brought to the screen (for example, an ear during a call) and automatically turns off the backlight to:

• 📵 Preventing Accidental Pressing During a Conversation.
• 🔋 Save battery power (screen is one of the main energy consumers).
• 🎧 Automatically switch to speaker when taking the phone away from the ear.

The Redmi 9T uses a model sensor, the STK3311 (or similar), which works in tandem with MIUI software. If the sensor is turned off or calibrated misfolded, the phone will behave as if no one is closing the screen — even when you’re talking on the phone.

💡

On some firmware, the proximity sensor is also responsible for the Raise to Wake function, and if it is unstable, check the sensor settings.

Signs of a non-functioning proximity sensor

How do you know if the proximity sensor on the Xiaomi Redmi 9T is disabled or broken?

• 📞 The screen doesn’t go out when you call, even if you press your phone to your ear.
• 🔄 Touch buttons respond to touches with the cheek or ear.
• 🔊 The sound automatically switches to the speaker, although the phone is pressed to the head.
• 📱 The sensor test menu (#6484##) next to the Proximity Sensor is on fire FAIL.

If at least one of these signs appears, the sensor is either turned off in the settings or requires recalibration. In rare cases, the problem can be hardware (damage to the plume or the sensor itself).

How to turn on the proximity sensor through the MIUI settings

In most cases, the sensor turns off after updating the firmware or resetting the settings to turn it on:

1. Open Settings → Applications → Application Management.
2. Click on the three dots in the top right corner and select Special Accesses.
3. Scroll down and tap the Sensors (or Sensor permissions in English firmware).
4. Find the Approximation Sensor and activate the switch.

If this is not the case, try an alternative route:

1. Go to Settings → System and device → More
2. Select Developer (if no option, activate Developer Mode by clicking 7 times on the MIUI version in About Phone).
3. Turn on the USB Debugging option and find Disable the sensors – make sure it’s turned off.

Is the sensor activated in "Special Accesses"?|Is the developer mode on?|Is the option "Disable sensors" disabled"?|Checked the sensor through the engineering menu?-->

Calibration of the proximity sensor on the Redmi 9T

If the sensor is on but not working properly (e.g., it is delayed or does not turn off the screen completely), calibration is required.

1. Open the Phone app and type the combination: ##6484## (or #4636## → Equipment Testing).
2. Select Proximity Sensor (proximity sensor).
3. Put the phone on a flat surface and press Calibrate.
4. After the process is complete, restart the device.

If calibration doesn’t help, try resetting the sensor settings through the hidden menu:

1. Enter the dialer: ##36446337##.
2. Go to the Proximity Sensor section.
3. Press Reset and confirm the action.

Verification of the sensor through third-party applications

If standard methods don’t help, install one of the sensor diagnostics apps:

How to use:

1. Install the application and open it.
2. Find the Sensors section or Sensors.
3. Put it on the Proximity Sensor.
4. Close the sensor with your hand – the value should change from 5.0 cm (or similar) to 0.0 cm.

💡

If the application shows Not available or values do not change when the sensor is closed, the problem is hardware – repair is required.

Hardware causes of sensor malfunction

If the software methods do not work, the problem may lie in:

• 🔌 Sensor plume damage (often after falls or disassembly of the phone).
• 💧 Sensor contamination (dust, moisture, greasy prints).
• 🔧 Motherboard malfunctions (problems with sensor power).
• 🔄 Wear of the sensor (rare, but occurs after 2-3 years of operation).

On the Redmi 9T, the proximity sensor is located next to the front camera, which is easily damaged when changing the glass or cleaning the speaker. If you recently dropped your phone or changed the display yourself, there is a high probability of mechanical damage.

⚠️ Warning: Do not try to clean the sensor with alcohol or sharp objects - this can damage the infrared filter. Use a dry soft brush or compressed air to clean.

What to do if the sensor is not turned on

If the sensor does not respond to any manipulations, follow the following steps:

1. Reset your phone to factory settings (Settings → About Phone → Reset) Pre-reverse the data.
2. Update your firmware to the latest version of MIUI through Settings → System Update.
3. Check your phone for viruses – some malware blocks the sensors.
4. Contact the service center if the problem is hardware. On the Redmi 9T, it costs 800-1500 rubles (depending on the region) to replace the sensor.

If the phone is warranty, don’t try to repair it yourself – this will void Xiaomi’s warranty obligations.

💡

Before visiting the service center, record a video showing a broken sensor, which will help the wizard to diagnose the problem faster.

Frequently asked questions