How to turn on the proximity sensor on Xiaomi Mi A3: full instructions with error analysis

Why you need a proximity sensor and how it works on the Xiaomi Mi A3

The proximity sensor on the Xiaomi Mi A3 is a small but critical component that automatically shuts down the screen during a phone call. Without it, you would constantly press buttons with your cheek or ear, turning the call on speaker, turning off the microphone or even completing a call. On the Mi A3, this sensor is based on an infrared sensor that detects the distance to the object (in this case, your head) and signals the system to extinguish the display.

But many users are faced with a situation where the sensor is not working properly: the screen does not go out when you bring the phone to your ear or, conversely, it turns off too early, most often not due to hardware failure, but to software settings or contamination of the sensor. In this article, we will discuss how to check the sensor, turn it on forcefully (if it is turned off), and also fix typical malfunctions without going to the service center.

The Mi A3 is a pure Android One, not a MIUI shell, which means that the paths to sensor settings may be different from other Xiaomi smartphones, and some features (such as manual calibration) are simply missing. But don’t worry, we’ll detail all the diagnostic and problem-solving options available.

Where is the proximity sensor on the Xiaomi Mi A3 and how to detect it

On the Mi A3, the proximity sensor is located at the top of the screen, to the right of the speaker (when you look at the phone in the standard position). Visually, it is hidden under the display glass, but you can determine its location by a small hole or point near the front camera. To accurately identify the sensor, do the following:

• 🔦 Turn on the flashlight on another smartphone and light up on the top frame of the Mi A3. The sensor will look like a translucent spot the size of ~2×2 mm.
• 📱 Run a test app to check the sensors (for example, CPU-Z Sensor Test – This will show the sensor activity in real time.

Important: don't confuse the proximity sensor with the light sensor, which is also located at the top of the screen, but is responsible for automatic brightness control. On the Mi A3, these sensors are placed nearby, but they perform different functions. If you notice that the screen not only does not go out when you call, but also stops automatically adjusting the brightness, the problem can be complex.

⚠️ Warning: Do not attempt to clean the sensor with alcohol or aggressive liquids! this can damage the oleophobic screen covering. Use only dry microfiber or special optics wipes.

How to turn on the proximity sensor on Xiaomi Mi A3: step-by-step instructions

In most cases, the proximity sensor on the Mi A3 is activated by default, but sometimes it can turn off after a system update or reset. To make sure the sensor is on, follow the following steps:

1. Make sure that the switch next to the option to Turn off the screen when approaching is in the on position.

If your firmware version doesn’t have a separate point for the proximity sensor, try an alternative path:

Settings → Applications and notifications → Additional → Special features → Phone settings → Approximation sensor

On the Mi A3 with Android 10/11, you can also use a hidden engineering menu to force the sensor to turn on.

Enter the code ##6484## in the phone application

Select the Proximity Sensor

Press Enable (if available)

Restart your phone to apply changes-->

⚠️ Warning: The engineering menu is designed for power users. Do not change other settings unless you are sure of their purpose - this can lead to unstable phone operation.

Checking the operability of the sensor: 3 reliable ways

Before you try to "repair" the sensor, make sure it's really faulty. Here are three diagnostic methods that work on the Mi A3:

1.A test over a bell

The easiest way is to call another phone and check the screen response:

• 📞 Dial the number and wait for the start of the call.
• 👂 Hold the phone to your ear (as in a normal conversation).
• 🔍 The screen should go out in 1-2 seconds. If it doesn't, the sensor doesn't work.
• 📱 Remove the phone from your ear – the screen should turn on again.

2. Use of testing applications

Install one of the following apps from Google Play:

• 📊 CPU-Z (Sensors section – shows the sensor values in real time (0 is a far object, 1 is an object close to you).

Normally, when you bring your hand to the sensor, the value should change from 5.0 cm (or similar) to 0.0 cm. If the readings do not change, the sensor is defective or blocked.

3. Verification through the engineering menu

For advanced users:

1. Enter the code ##4636## in the phone app.
2. Select Usage statistics (Usage statistics).
3. Click on the three dots in the upper right corner and select Sensor test.
4. Find the Proximity sensor string and check the reaction to the approach of the hand.

Typical proximity sensor problems on the Mi A3 and their solutions

If the sensor is on but not working properly, the reasons may be as follows:

A critical feature of the Mi A3: on this model, the proximity sensor often conflicts with some versions of Google’s Phone app. If the problem occurs after updating this app, try rolling back to version 70.0 or lower.

Another common cause of malfunction is poor quality protective films. Many films have an opaque layer in the sensor area that blocks the infrared signal. Try temporarily removing the film and repeat the test. If the sensor works, replace the film with a model with a cutout for sensors (for example, Spigen Glas.tR EZ Fit).

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If the sensor stopped working after the phone fell, don't try to disassemble it yourself! in the Mi A3, the sensor plume is very fragile and easily damaged when unqualified repairs are made.

Calibration of the proximity sensor: myths and reality

Many users are looking for ways to calibrate the proximity sensor on the Mi A3, but Android One (unlike MIUI) does not have a built-in tool for manually adjusting the sensor. All tips for calibrating through an engineering menu or third-party applications have no evidence base and often lead to the opposite effect - even more instability.

However, there are a few safe ways to reset the sensor settings to factory:

• 🔄 Reset the settings of the Phone Application (in Settings) → Annexes → Phone. → Warehouse → Drop it).
• 📱 Perform a soft reset of the phone (without deleting data): pinch the power + Increase volume by 10 seconds.
• 🔧 Update the firmware to the latest version (often new builds fix bugs with sensors).

If you still want to try the “calibration” through the engineering menu, do the following:

1. Enter the code ##6484##.
2. Select Proximity Sensor.
3. Press Calibrate (if the option is available).
4. Place your phone on a flat surface and wait until the process is complete (don’t interrupt!).

⚠️ Note: On some versions of the Mi firmware A3 The calibration option may be missing or result in a Sensor not supported error, in which case the only way out is to reset or contact the service.

What to do if nothing helps: hardware malfunctions

If the software methods failed, the problem is likely hardware. In the Xiaomi Mi A3, the proximity sensor may fail for the following reasons:

• 💧 Moisture falling under the screen (even after successful drying, the oxidation of contacts may occur later).
• 🔨 Mechanical damage to the sensor plume when the phone falls or disassembles.
• ⚡ Static electricity that damages the sensor chip (rarely but possible).
• 🔋 Faulty motherboard (in this case, other symptoms are usually observed, for example, spontaneous reboots).

The cost of replacing the proximity sensor with the Mi A3 in service centers varies from 800 to 1500 rubles (depending on the region).

• A special tool for neat screen tweaking.
• Experience with microelectronics (the plumes are very fragile).
• The original sensor (Chinese analogues are often incompatible)

Before visiting the service, check whether your phone is under warranty. Even if the warranty period has expired, some Xiaomi service centers go on layoffs and repair devices at reduced prices for regular customers.

FAQ: Frequent questions about the proximity sensor on the Xiaomi Mi A3

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If the proximity sensor on the Mi A3 stopped working after the system update, try to roll back on the previous firmware version first, often solving the problem without interference with the hardware.