Checking the proximity sensor on Xiaomi Redmi 7A: from diagnosis to repair

Why the Redmi 7A's proximity sensor is failing and how to determine it

The proximity sensor in the Xiaomi Redmi 7A is a small but critical element responsible for turning off the screen during a phone conversation. If it breaks, you risk accidentally pressing buttons on your face or ear during a call, leading to crashes, unintentional actions or even a communication break. Typical symptoms of malfunction: the screen does not go out when you bring the phone to your ear, accidental pressing during a conversation, or, conversely, the screen does not turn on after the call is completed.

The causes of failure range from software failures to physical damage, most often the problem lies in:

• 📱 Sensor contamination – dust, grease, or protective film can block the infrared signal.
• 🔧 Damage after falling – even a minor impact can displace or damage the sensor.
• 🖥️ Firmware failure - errors in the system MIUI This can cause the sensor to work incorrectly.
• 🔌 Contact oxidation – moisture or corrosion on the board disrupts the connection.

Before you take your phone to a service center, you should check the sensor's performance yourself, and 80 percent of the time, it's software or simple cleaning, and then we'll look at all the diagnostic tools available, from built-in tests to third-party applications.

Method 1: Check through the engineering menu (code ##6484##)

The most reliable way to diagnose is to use a hidden engineering menu, which is available on all Xiaomi smartphones and allows you to test the sensor without additional applications.

1. Open the Phone app.
2. Enter the combination: ##6484## (some firmware may require ##4636###).
3. Select Proximity Sensor (Proximity Sensor).
4. Close the top of the screen with your hand – the value should change from 5 (maximum distance) to 0 (object nearby).

If the values do not change or the Failed error is displayed, this indicates a hardware malfunction. On the Redmi 7A, the normal value at rest is 5 cm, at closing - 0 see Deviations of more than 1 cm are considered critical.

Charge your phone at least 30 times%|Remove the cover and protective film|Being in a well-lit place|Close all background applications-->

⚠️ Note: Some custom firmware may have the engineering menu blocked. If the code doesn't work, try an alternative method through the app MIUI Hidden Settings (available on Google Play).

Method 2: Diagnostics with Phone Doctor Plus

If the engineering menu isn't available or you prefer a more visual interface, use third-party utilities. One of the best is Phone Doctor Plus, which tests all of your smartphone's sensors, including the proximity sensor. Download it from Google Play and follow the instructions:

1. Launch the application and press Start Test.
2. Scroll to the Sensors section.
3. Select Proximity Sensor.
4. Follow the hints on the screen: Close the sensor with your hand and make sure the indicator changes color from green to red.

The app also shows the sensor response time (in milliseconds). For the Redmi 7A, the normal value is up to 200 ms. If the response is greater than 500 ms, this may indicate sensor wear or firmware problems.

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If the sensor only responds to certain objects (e.g., the hand, but not the table), the problem may be the lens contamination. Try gently wipe the sensor area with a cotton swab dipped in alcohol.

Method 3: Visual inspection and cleaning of the sensor

Often the problem is the simple pollution, the proximity sensor on the Redmi 7A is located at the top of the screen, next to the front camera, and it is easy to see from a small circular hole (sometimes it is closed with transparent film).

• 🧴 Use isopropyl alcohol (at least 70%) and cotton swab.
• 🔍 Light the sensor with a flashlight – dust or fat will be visible as dark spots.
• 🧽 Gently wipe the sensor area without pressing hard (risk of damaging the lens).
• 🕒 Let your phone dry for 5-10 minutes before the test.

If the sensor doesn't work after cleaning, check if it's getting in the way of a protective glass or a film, if it's not working, if it's not good enough, if it's not good enough to block the infrared signal, then try temporarily removing the protection and repeating the test.

Method 4: Checking through ADB (for advanced users)

If standard methods fail, you can use Android Debug Bridge (ADB) for deep diagnostics, which requires connecting your phone to your computer and basic command line knowledge.

1. Enable USB Debugging in the Developer Settings → About Phone → MIUI Version – Press 7 times, then go back to Additional Settings → For Developers.
2. Connect Redmi 7A to your PC and open the command line (or Terminal on Mac/Linux).
3. Enter the command to check the sensor: adb shell dumpsys sensorservice
4. Find the line with proximity in the output - there will be current readings.

If the output does not contain sensor information or if errors such as No such sensor are displayed, this may indicate:

• 🔌 No contact between the sensor and the motherboard.
• 🖥️ Damage to firmware at the core level.
• 🔧 Full sensor failure.

⚠️ Attention: Use ADB The wrong commands can cause the system to fail. If you're not sure what you're doing, skip this method or consult a specialist.

Method 5: Hardware diagnostics (disassembly of the phone)

If all software methods are exhausted, you have to check the physical condition of the sensor. 7A. You'll need it:

• 🔧 Plastic blade or mediator.
• 🔨 Cross screwdriver (size) PH00).
• 🧲 Magnetic propeller substrate.
• 📸 Camera (to capture the location of the parts).

Procedure:

1. Turn off the phone and remove it. SIM-map.
2. Heat the back cover with a hairdryer (temperature not higher than 60 ° C) - this will soften the glue.
3. Carefully tuck the lid with a plastic spatula, starting at the corners.
4. Unscrew 8 screws holding the metal plate.
5. Disconnect the battery plume (required!), then find the front camera plume with the sensor.
6. Check the integrity of the plume and the contacts on the board. Oxidation or cliffs are a common cause of malfunction.

If you find damage, you'll need to replace the plume or soldering of the contacts. On the Redmi 7A, the proximity sensor is built into the front camera module, so you'll have to change the entire unit, its article is MDY07-001 (original) or MDY07-001-CN (Chinese version).

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Disassembling the phone will void the warranty (if it is still valid).If you do not have experience in electronics repair, you should contact the Xiaomi service center or an authorized workshop.

What to do if the sensor does not work: an algorithm of actions

Based on the results of the diagnosis, make a plan of further actions:

If you choose to use the service, choose workshops with good reviews and original parts. Redmi 7A often installs non-original sensors that fail after 2-3 months. The original module can be ordered on AliExpress (search for MDY07-001) or in Xiaomi branded stores.

FAQ: Frequent questions about the proximity sensor on the Redmi 7A