Xiaomi’s Redmi Note 4 line of smartphones is deservedly considered one of the most reliable devices of its time, but even they have specific hardware problems. One of the most common complaints of users is the incorrect operation of the proximity sensor, which is responsible for turning off the screen during a conversation. If the screen goes out too early, does not go out at all or, conversely, does not light up after the dialogue is over, it causes tremendous discomfort when communicating.
Before you take a device to a service center or buy a new phone, you need to conduct a thorough diagnosis to understand the nature of the malfunction. Often the problem lies not in the physical failure of the sensor, but in software failure, contamination of the protective glass or improper calibration. In this article, we will discuss in detail all the available ways to check and adjust this module.
There are several testing methods, ranging from built-in system utilities to third-party applications and engineering menus. It is important to understand that the proximity sensor on the Redmi Note 4 (a model with a Snapdragon processor) and the Redmi Note 4X (often on MediaTek or Snapdragon depending on the region) can behave differently due to differences in the MIUI software shell. Below we will look at the universal methods relevant to most versions of the firmware.
Checking through CIT's engineering menu
The most reliable and quickest way to diagnose is to use the built-in CIT (Customer Integration Test) menu, which is designed for factory testing of equipment and allows you to check each module of the smartphone separately, without installing third-party software.
To run the test, you need to open the standard Phone app and dial a special character combination. Dial the code ##6484## or ##4636## (code can vary depending on the version of MIUI). Immediately after entering the last character, a menu with a white background and a test list will open.
Once you select the appropriate item, a window will appear on the screen with numerical values or status indicator. Hold your palm to the top of the screen, closing the area of the auditory speaker. If the sensor is correct, the values on the screen should change (for example, from 5.0 to 0.0 or the color of the indicator will change from red to green), This indicates that the sensor responds to the obstacle correctly.
☑️ Checking in CIT menu
It's worth noting that in some versions of firmware, the test can show false positives if the screen is equipped with a low-quality protective glass, in which case the engineering menu will show that the sensor is working, but in reality, when you talk, the screen will go out in your pocket, so the CIT test is the primary, but not always the final stage of diagnosis.
What if the code doesn't work?
Use of third-party applications for diagnosis
If access to the engineering menu is limited for some reason or you want to double-check the data with a more detailed tool, specialized applications from the Google Play store will be an excellent solution. They allow you to visualize the operation of the sensor in real time and often provide more flexible settings for calibration than standard system tools.
One of the most popular and functional tools is the Proximity Sensor Reset/Fix or Sensor Test application. Once installed and launched, the program asks for permission to access the sensors. On the home screen, you will see a graph or numerical value that varies depending on the distance to the object, which allows you to assess not only the fact of the operation (is / is not), but also the sensitivity of the sensor.
Unlike the standard test, third-party utilities often know how to work in the background or display a floating window, which is extremely convenient for checking the behavior of the sensor directly during a call simulation. You can run a test, put the phone on the table and put your hand, simulating the putting to the ear, watching the reaction of the screen in real time.
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When using third-party testers, pay attention to the Max Range setting. If the maximum detection distance is less than 3-5 centimeters, the sensor may be contaminated or have a hardware defect.
However, for a basic check of the health (works / does not work) of the rights of the superuser is usually not required, just watch the change in the readings in the program interface when the top of the screen is blocked.
Verification through system settings and calibration
There is a hidden mechanism in the MIUI shell for calibrating the proximity sensor, which often helps to eliminate the problem of phantom pressing or not turning off the screen, a technique that is especially relevant if tests show that the sensor is physically fit but behaves inadequately in everyday use.
To enter calibration mode, you often need to perform certain actions in the About Phone menu. Go to Settings -> About Phone and find the Kernel version. You need to click on this line 5-10 times in a row until the hidden sensor calibration menu opens. If this method does not work, try finding the Approximation Sensor item in the CIT menu you mentioned earlier and clicking on the Calibration button.
In the window that opens, you'll see an instruction that typically asks you to close the top of the phone with your palm and press Calibrate, then remove your hand and press Calibrate again, a process that allows the system to remember the minimum and maximum light values the sensor reads and set the correct trigger threshold.
| Method of verification | Required rights | precision | Difficulty |
|---|---|---|---|
| Engineering Menu (CIT) | No. | Tall. | Low. |
| Third-party annexes | No (for the test) | Medium | Low. |
| Manual calibration | No. | Tall. | Medium |
| Disassembly of the device | Physical access | Maximum | Tall. |
Once you've calibrated successfully, be sure to restart the device, the system will apply new parameters, and the behavior of the screen during the calls must change, and if after calibration the problem persists, it's likely that the problem is a software conflict or physical damage to the component.
Hardware causes of malfunctions
If the software methods have failed, you should consider the hardware reasons: the proximity sensor in the Redmi Note 4 is located at the top of the screen, next to the speaker. The design of the smartphone is such that there is a small gap between the protective glass and the sensor itself, which can fill with dust, moisture or pile.
A common cause of false positives is poor-quality protective glass. If the glass has a black opaque frame that covers the area of the sensor, or if it is glued with bias, the sensor will constantly "see" the obstacle, in which case the screen will go out immediately after the call begins or will not light up when the phone moves away from the ear.
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A wide black framed glass is the reason №1 proximity sensor issues on Xiaomi.Try temporarily remove it for check.
It is also worth checking whether the upper body is deformed, and even microscopic bends or battery bloating (which is rare but happens) can put pressure on the sensor plume, disrupting its operation, and visual inspection and careful disassembly (if you have the skills) will help to identify such defects.
In some cases, the contacts of the plume connecting the sensor to the motherboard become oxidized, which can occur after moisture is injected or just over time, and cleaning the contacts with alcohol and reconnecting the plume often bring the node back to life without the need to replace parts.
Programmatic conflicts and updates
Do not discount the software errors of the Android operating system itself or the MIUI shell. After updating the firmware, Redmi Note 4 users often reported the appearance of sensor bugs, this is due to the fact that new drivers may incorrectly interact with the hardware of a particular revision of the device.
Check if you have an app that controls calls or records conversations that takes precedence over system functions. These programs can block the proximity sensor. Try to start your phone in Safe Mode. To do this, press the off button, and when the reboot menu appears, keep your finger on the "Stop" (or "Reboot", depending on the Android version) for a long time until you get a suggestion to go to Safe Mode.
If the sensor is working correctly in Safe Mode, it means that the problem is caused by one of the installed applications. Start removing newly installed programs or those that have access to the phone and contacts until you find the culprit.
⚠️ Warning: Resetting your factory settings will completely delete all your data.Be sure to back up your contacts, photos and important documents in the cloud or on your computer before doing this.
If nothing works, the ultimate software method is to completely reset the settings, which will eliminate any software errors that have accumulated over time, but if the sensor is acting strangely after the reset, the probability of hardware failure is close to 99%.
Solving problems with screen and protective films
The topic of security accessories deserves special attention. As mentioned, glass can overlap the sensor, but there is another problem: some types of glasses have the ability to store static electricity or distort the infrared radiation that the sensor uses.
Try to gently wipe the top of the screen with an alcohol napkin, paying special attention to the area around the speaker. Fat spots from the skin of the face can also affect the sensitivity of the sensor, although to a lesser extent than the physical overlap.
If you use a case with high sides, check if it covers the top end of the smartphone. In the case of the Redmi Note 4, the sensor is quite close to the edge, and a massive shockproof case can become a hindrance.