The situation when the smartphone screen does not go out during a conversation, and the cheek presses random buttons or challenges to hold, is familiar to many Xiaomi owners. This is a classic symptom of contamination or incorrect operation of the proximity sensor. In Xiaomi and Redmi devices, this sensor is often hidden under the upper end of the case, making it vulnerable to dust and grease, especially if you use a protective glass with narrow cutouts.
Ignoring the problem can lead to significant discomfort in operation, as the device stops responding to the touch to the ear. Infrared sensor sends a beam and reads the reflection; if in the path of the beam there is dirt, the phone “thinks” that it is in the pocket, and locks the display. In this article, we will discuss proven ways to physically clean the sensor and program calibrate through the system menu.
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Before starting any manipulations, be sure to turn off your smartphone to avoid accidental pressing or short circuiting when moisture hits.
Principle of operation and causes of failure
The proximity sensor in Xiaomi smartphones is a compact module consisting of an infrared LED and a receiver that emits invisible light and analyzes the amount of reflected light. When you bring the phone to your ear, the distance decreases, the amount of reflected light increases, and the system blocks the screen. If the sensor is contaminated, it constantly receives a signal about a nearby object.
The main cause of failure is the banal hygiene of operation. Skin grease, dust from pockets, pile from covers, all this settles on the upper edge of the device. Especially often the problem occurs in models with a virtual home button, where the sensor is hidden in a narrow gap above the display, and the cause can be a poor protective glass that covers the sensitivity zone.
- 🧼 Accumulation of a layer of fat and dirt in the microhole above the screen.
- 🛡️ Use of protective film or glass incompatible with sensor design.
- 💧 Moisture or condensation entering the sensor area.
- 📉 Software calibration failure after update MIUI.
In some cases, the problem is deeper and involves mechanical damage to the plume or module itself after a fall, but in 90% of cases, simple cleaning and re-tuning helps, and it is important to understand that aggressive chemistry can damage the oleophobic coating of the screen or the sensor plastic itself, so you need to act carefully.
Preparation for cleaning: necessary tools
Before you start to act, you need to prepare the workplace and tools. You don't need a complex repair kit, but using the wrong materials can make things worse. The main goal is to remove the contamination without scratching the surface and pushing the dirt even deeper inside the case.
It's perfect for isopropyl alcohol or a special liquid to clean electronics, ordinary water can leave a stain, and household chemicals can damage adhesives, you'll also need a lilaless microfiber wipe that leaves no fiber, and a wooden toothpick or plastic blade to carefully remove dried particles.
⚠️ Attention: It is strictly forbidden to use cotton swabs, since their villi can get stuck in the sensor hole and finally block its operation!
Make sure your smartphone is off. This not only protects your device from short circuits, but also allows you to see the contamination on the black screen better. If you have a black-framed safety glass installed, make sure it doesn't cover the sensor area, otherwise cleaning the phone itself won't work.
☑️ Cleaning tools
Physical cleaning of the proximity sensor
Cleaning requires patience and good lighting, and you can find a small hole or dark area on the top of your smartphone, which is the infrared module's location, and it often looks like a tiny black dot next to a speaker, and that's where you want to focus your effort.
Moisten the microfiber with alcohol a little. The fabric should be barely wet, it should not drip. Gently wipe the top edge with circular motions. If the pollution is severe, you can use a toothpick wrapped in microfiber to delicately clean the recess. The movements should be sweeping from center to edge.
To remove dust from the depths of the hole, a compressed air can is great. Short jets will help dislodge dry particles that interfere with the sensor. After processing, wipe the surface with the dry part of the napkin and let the alcohol completely evaporate before turning on the device.
| Tool. | Efficiency | Risk of damage | Recommendation |
|---|---|---|---|
| Microfiber | Tall. | Low. | Basic instrument |
| Cotton swab | Medium | High-pitched | Not recommended |
| Compressed air | Tall. | Low. | For dry dust |
| Toothpick | Medium | Medium. | Only with caution. |
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The main difficulty of cleaning Xiaomi is a narrow hole of the sensor, where it is easy to drive dirt deeper if you act rudely.
Software calibration through the engineering menu
If the physical cleaning didn't work, the software calibration may have gone wrong. There's a hidden engineering menu in the MIUI shell that allows you to reset the sensor. It uses a special code to enter it, which works on most Redmi and Xiaomi models. Open the Phone app and type in the ##6484## combination.
Once you enter the code, you will see the CIT (Customer Information Test) menu. In the test list, look for the Proximity Sensor (often referred to as the Approximation Sensor). Click on it. You will see a screen with two values: Near (close) and Far (far). Close the sensor with your finger — Near should change, remove your finger — Far will change.
To reset, press Calibration or Refresh (depending on the MIUI version). Follow the instructions on the screen: usually close the sensor and press the button, then open and press again. Once successful, the message "Pass" will appear. Reboot the smartphone to make the changes effective.
⚠️ Note: Do not change other options in the engineering menu CIT, If you're not sure what they're doing, it can cause other modules in the phone to malfunction.
What if the code doesn't work?
Resolving problems with protective glass
One of the most common reasons why the proximity sensor doesn't work on Xiaomi is because of the incompatibility of the protective glass. Accessories manufacturers often make the black frame too wide to cover the sensitivity zone. Visually, this may be invisible, but for an infrared beam it is an insurmountable barrier.
It's easy to test this: remove the protective glass and repeat the test in the engineering menu. If the sensor works perfectly without glass, and the glass is "glutty," the problem is found, in which case there are two ways: accept and remove the glass, or buy a new one, labeled Full Coverage or specially designed for your model with the right cutouts.
Sometimes it helps with the gluing glass, if there's a bubble of air underneath it just above the sensor, it will distort the readings, and if you warm the glass carefully with a hairdryer, you can try to squeeze the air to the edge, or you can replace the accessory completely, and ignoring this fact will lead to constant problems with the screen during calls.
- 🔍 Check if the black glass frame covers the sensor hole.
- 💨 Remove air bubbles above the sensor area.
- 🔄 Replace the glass with the right cutout model.
- 🧹 Clean the inside of the glass before re-installing.
Additional settings and applications
Some versions of the MIUI shell have an additional setting to ignore false sensor alerts, which can be found along the way: Settings → Lock and Protection → Pocket Mode. Disabling this feature can help if the sensor is contaminated, but you don’t want to clean the phone right now (although it’s a temporary solution).
There are also third-party apps from the Play Market, like Proximity Sensor Reset & Fix, that use the same calibration algorithms as the engineering menu, but in a more user-friendly interface, but beware: many of these apps contain ads and may ask for extra permissions.
If nothing works, you can try to upgrade the system or, conversely, roll back to the previous version of the firmware if the problem appeared after the update. Sometimes bugs in the MIUI code affect the operation of sensor drivers, and developers fix this in security patches.
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Use the “Increase” feature in accessibility settings to better see the fine details and contamination around the sensor when cleaning.
When a module replacement is required
There are situations where software and cleaning are powerless, and if after all the manipulations in the CIT test, the values don't change at all, or change randomly without touching, there's a hardware defect, and it could be a plume break, the contacts oxidize after water hits, or the IR emitter itself fails.
In such cases, you need to disassemble the smartphone. On models with a non-removable back cover, this is more complicated and requires heating the perimeter of the case. You need to disconnect the display plume, because often the proximity sensor is soldered on the board of the screen plume or connected by a separate connector next to it. Replacing is inexpensive, but requires skill.
If your phone is warranty-free, it is best not to open it yourself. Contact an authorized Xiaomi service center. Self-disassembly is guaranteed to lead to loss of warranty service, even if the problem was originally industrial.