Xiaomi, Redmi and Poco smartphone owners often face the need to diagnose devices in depth beyond standard settings, with the “fingerprint test Xiaomi” becoming a key technical support request, meaning fingerprint scanner testing, a procedure that is necessary when the fingerprint sensor is incorrect, no longer recognizes fingers the first time, or does not respond to touch at all.
Understanding how to run a fingerprint test allows the user to determine whether the device is malfunctioning or physically damaged. Unlike a simple reboot, the engineering test gives access to the sensor's raw data, showing the actual state of the biometrics reading, a critical step before going to the service center.
In this article, we will take a look at all available verification methods, including hidden codes, ADB use and third-party software. You will learn how to interpret diagnostic results and what actions to take if the test shows critical errors. Competent diagnosis is the first step to restore the security of your device.
What is Fingerprint Test and Why You Need It
Fingerprint test is a specialized diagnostic mode built into the MIUI or HyperOS software shell. Its main function is to force the fingerprint scanner to activate its hardware and software components without unlocking the phone and logging in, which allows you to isolate the problem from the influence of third-party applications or security settings.
The need for such a check arises when a number of alarming symptoms appear: if your smartphone begins to “forget” fingerprints, unlocking occurs only from the fifth or sixth time, or the screen goes out when you try to scan, these signals can not be ignored. Systematic failure of the scanner can indicate the degradation of the plume or oxidation of contacts, which over time will lead to complete inoperability of the module.
Using the built-in test helps to separate the software glitch from the hardware. If the scanner is perfect in the test mode and the system is not, the problem lies in the firmware or application conflict, and if the test fails or fails, it is a physical failure.
⚠️ Attention: Frequent use of intensive testing mode can cause accelerated wear and tear or heat on the scanner surface. Use diagnostic tools only if there are real recognition problems.
Access through CIT (CIT Test) Engineering Menu
The most reliable and secure way to run a fingerprint test on Xiaomi devices is to use a built-in engineering menu known as the CIT (Customer Integration Test), which is hidden from the average user, but is accessible through a special set of commands in the Phone app.
You don't need root rights or a computer connection to enter the diagnostic menu, just know the correct code. However, the instruction set may vary slightly on different versions of MIUI firmware. The standard and most versatile code for entering the full test menu is ##6484##.
Once you enter the code, you'll see a list of all the available hardware tests on your smartphone, and you'll need to find the item associated with the fingerprints, which can be called Fingerprint, FPC Test (if you use an FPC sensor), or Goodix Test.
☑️ Algorithm of verification through CIT
The test interface usually requires the user to apply a finger to the scanner a certain number of times (usually 5-10).The system analyzes the speed and accuracy of the reading. If all stages are successful, you will see a green inscription "Pass". If you fail, a red message "Fail" with an error code will appear.
Using ADB commands for deep diagnostics
For advanced users who don’t have a standard CIT menu, there is an ADB (Android Debug Bridge) check method that allows them to access the scanner’s logs in real time and run specific tests that are not available through a regular interface.
Before you start, you need to turn on Developer Mode and activate USB Debugging in your smartphone settings. Once you connect the device to your PC and install the drivers, you can send commands directly to the system, which is especially useful if the phone screen is not working or the sensor is locked software.
One of the useful commands for checking the status of biometrics is to ask for the status of the sensor, which in the terminal looks like asking the system about the presence and status of the input devices connected, and more complex commands may require root access, but basic diagnostics can be done without them.
adb shell dumpsys fingerprintThis command will show you a detailed log of the fingerprint service, and you can see at the locks how often the read errors occurred, when the sensor last activated, and if there are critical crashes in the driver, and you need to be careful about analyzing the log text: look for lines with the word "Error" or "Fail."
What if the ADB can’t see the device?
Table of the main codes for diagnostics Xiaomi
In addition to the basic code for logging into the full menu, there are specialized commands that can immediately open the desired section or check a specific module, and knowing these codes saves time with frequent diagnosis of multiple devices.
The table below shows the most relevant commands for Android-based devices and MIUI shells. Please note that some global firmware versions may restrict access to the engineering menu.
| Team code | Function | Status of work |
|---|---|---|
| ##6484## | Full CIT menu (including scanner test) | It works on 95% of devices. |
| ##4636## | Menu of information about the phone and battery | Basic information |
| ##7780## | Resetting settings (caution!) | Requires confirmation. |
| *#06# | IMEI code verification | Universal code |
| Use codes with caution, some of which may result in data resets. |
Results analysis and error codes
When you get a test result, it's important to interpret it correctly. Xiaomi's diagnostic system usually gives you a binary result: success or failure. However, the word "Fail" can hide the different nature of the problems. If the test is not passed, pay attention to the behavior of the LED indicator (if any) or vibration.
A common cause of error is software conflict. Once the MIUI firmware is updated, the old fingerprints may become incorrect. In this case, the fingerprint test will show an error, but deleting old prints and registering new ones will solve the problem. This is the classic case of hardware being intact and data being corrupted.
If the scanner does not respond even in test mode, does not emit vibrations and does not light up (on underscreen scanners), there is a high probability of a plume breaking, which often happens after a phone falls or moisture enters the body.
⚠️ Warning: Don't try to disassemble the phone to check the scanner plume unless you have experience. Underscreen scanners are extremely sensitive to static electricity and mechanical pressure. Inept intervention can permanently disable the module.
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Before going to the service center, take a screenshot of the Fail test result, which will prove to the master that the problem is not in your settings, but in the hardware, and will help avoid unnecessary questions.
Third-party testing applications
If Xiaomi’s built-in tools are not available or give incorrect results, you can use apps from the Google Play store. There are many utilities, such as “Phone Tester”, “TestM” or “Device Info HW”, which can read information about biometric sensors.
These applications don't have access to a deep engineering menu, but they can show if the operating system sees the scanner at all. The Sensors section should have a device called Fingerprint. If the list is blank or the status of the device is Disconnected, the problem is systemic.
Using third-party software also allows you to check the performance of other sensors, such as an accelerometer or a gyroscope, which is sometimes useful for a comprehensive assessment of the condition of the smartphone after a fall.
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Third-party applications are good for initial sensor visibility checks by the system, but only use the built-in CIT menu to accurately diagnose sensitivity and response rate.
Frequent problems and ways to solve them
One of the most common problems is that the scanner's response rate decreases over time, often not because it breaks down, but because it contaminates the surface of the sensor or screen, and fatty footprints, dust and moisture interfere with the reading of a fingertip.
Regularly wiping the scanner area with a soft cloth without a pile, in most cases, returns the same speed, and if that doesn't help, try removing all the saved prints and registering them again, changing the angle of the finger with each application, which will create a more complete digital profile.
In rare cases, the problem lies in the protective film, too thick or poor quality glass can block the signal, especially on underscreen scanners, filming is a great way to test this hypothesis.