How to check the sensor on Xiaomi Redmi 4X: diagnostics

Screen responsiveness issues on Xiaomi smartphones often come as an unpleasant surprise, especially on time-tested models like the Redmi 4X. If the display has stopped responding to touch, "gluts" or opens apps chaoticly, diagnostics are urgently needed. Owners of Android devices often confuse software failures with physical damage to the digitizer, which leads to unnecessary repair costs.

In this article, we will discuss in detail how to test the sensor on Xiaomi Redmi 4X, using built-in system tools and hidden engineering codes, you will learn how to distinguish between temporary software freezes and real-life breakdowns, and also learn whether the problem can be solved software or if you need to replace components.

Diagnosis begins with visual inspection and analysis of the system's behavior, often because of cheap protective glass or surface contamination, rather than because of the failure of the module itself. However, if the screen is dead in certain areas or reacts with a long delay, a deep check through the screen will be required. CIT-menu.

External examination and primary diagnosis

Before running complex test programs, eliminate trivial factors: first remove the protective glass or film; cheap accessories can create static electricity or simply have defects that distort the capacitive layer; wipe the display with soft cloth moistened with a special tool to remove greasy traces, which are often perceived by the system as “ghost touches”.

Notice that there's physical damage. Cracks on the glass can damage the plume that connects the display to the motherboard. Even a microscopic chip in the corner of the screen can disrupt the entire matrix. If there's any trace of falling or moisture on the body, the probability of a touchscreen malfunction increases by up to 90 percent.

⚠️ Warning: If the screen is broken but the phone responds to touch, back up the data immediately. At any time, the sensor may fail completely and you will lose access to the information.

Check the battery. With a low charge level (less than 10-15%), some Xiaomi models can artificially limit the sensitivity of the screen to save energy. Also try to turn off the charger: cheap power supplies often cause interference, which makes the sensor “go crazy”.

Using the CIT Engineering Menu to Check

The most reliable way to test the sensor on Xiaomi Redmi 4X is through a built-in engineering menu that allows you to run hardware tests on each component of the phone separately from the main operating system, without needing root rights or a computer connection to log in.

Open the Phone app and type in the combination ##6484##. The CIT menu should appear on the screen. If the code doesn't work, try the alternative ##4636##, although it's more commonly used for battery and network information. The CIT menu presents a list of all the components of the device.

In the test list, look for Touchpanel or Touchscreen, and you click on it, and you open a black field that responds to touch, and it's the primary tool for detecting dead zones, and you swipe all over the screen, and you want the line to be continuous and clear, and if you're in a certain place, you're interrupted or not drawn at all, you're in that area, and you're in contact with the sensor.

Multi-touch and "dead zones" test

The multi-touch check feature in the engineering menu lets you determine how many simultaneous touches your Redmi 4X recognizes. At the top of the test mode screen, a dot counter is displayed. The norm for this model is support for up to 10 simultaneous touches.

Put your phone on a flat surface and touch the screen with several fingers at the same time. If the counter shows fewer dots than you touched, or the dots "shake" and move on their own, this is a sign of a malfunction of the power controller or plume. Also pay attention to the corners of the screen - this is where the most often appear defects after falls.

To get a closer look, third-party tools from Google Play, such as the MultiTouch Test, can visualize each touch as a colored circle, helping to identify phantom clicks when the phone opens apps or prints text without the user's input.

Screen calibration on Xiaomi Redmi 4X

Sometimes the sensor is physically fit, but it's software calibrated, which happens after a failed firmware update or a service display change, and MIUI doesn't have a built-in calibration function in normal settings, but it can be activated through an engineering menu.

Same menu. CIT Choose eTouch or Calibration. Follow the instructions on the screen: you usually need to click on certain dots or draw a figure. If standard calibration methods don't work, you can use it. ADB-Teams, but it requires a PC connection.

To reset calibration settings via console (USB debugging is required):

adb shell settings put secure touch_sensitivity 0

Once the command is executed, the device must be restarted, and if the problem was a software calibration failure, the screen must start working correctly, otherwise it is an ironclad problem.

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Before calibration, be sure to remove the protective glass, even a quality film can make errors in determining the coordinates of the touch.

Comparison of symptoms: Software or Hardware

To avoid carrying the phone to the service unnecessarily, it is important to properly classify the symptoms. Software failures can often be fixed by rebooting or resetting settings, whereas hardware breakdowns require the intervention of a wizard.

If the phone responds to voice assistant commands or volume buttons are working but the touchscreen is dead, chances are the problem is in the sensor layer itself.In the case of the Redmi 4X, a frequent cause is the plume's drift due to old age glue or impact.

Resetting and radical measures

If the tests are CIT-The menu shows that the sensor is technically sound (line is drawn everywhere, multi-touch works), but there are problems in the system, it is worth trying a software reset.

Go to Settings → Advanced Settings → Recovery and Reset. Select “Clear all data.” Remember, this step will remove all photos, contacts and apps from your device. Be sure to save important data to your computer or the cloud before reset.

⚠️ Warning: If the sensor continues to malfunction after a complete reset and reinstallation (via Recovery), the software methods are powerless.

In some cases, Safe Mode helps. Press the switch off button, and when the reboot menu appears, (hold on for a long time) the "Stop" option on the screen. The phone will suggest that you go to Safe Mode. If the sensor is working perfectly in this mode, then one of the applications you have installed is causing the problem.

Frequent questions about the Redmi 4X repair

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If CIT-The Touchpanel test was successful, but there are problems in the system, either looking for a conflicting application or doing a full reset.