Xiaomi, Redmi and Poco smartphone owners often face the need to conduct a deep diagnostic of the device, which may be required after buying a gadget from hand, if a factory defect is suspected, or after a failed fall of the device. Unlike many other manufacturers, Xiaomi has built a powerful hidden tool into the shell of MIUI and HyperOS to check hardware and software modules.
Using a special engineering code, you can run an automatic or manual test of each component of a smartphone without installing third-party applications. Diagnostics covers the display, touchscreen, microphones, speakers, vibration, buttons and even proximity sensors. This is the most reliable way to ensure that the device is healthy before you start active use.
In this guide, we will discuss in detail how to activate the verification mode, interpret test results and what to do if a module is not working correctly. Check all the functions will take only a few minutes, but will give you comprehensive information about the technical condition of your gadget.
Activation of the engineering diagnostic mode
You don't have to have super-user rights or connect your phone to your computer to access the hidden test menu, and all the tools you need are already built into the standard Phone app, and the engineering menu is available on the vast majority of models released in the last 5 years.
To start the check, open the standard “caller” and dial a special one. CIT-For Xiaomi devices, this is a combination of ##64663##. Some older firmware versions or specific regions may use code ##4636##, but the first one opens the full list of hardware tests.
Once you enter the last digit or asterisk, the standard dialing interface will disappear and the test list will appear on the screen. If the menu does not open automatically, make sure you do not allow typos. On some global firmware versions, access to full functionality may be limited, but basic tests are usually saved.
What if the code doesn't work?
The menu interface is a list of all available modules, and the top button is usually the Automatic Test button, which triggers a sequential check of all components without the user's input, but for the most accurate diagnosis, it is recommended to go through each item manually to personally evaluate the quality of the image, sound and tactile impact.
Diagnostics of the display and touch screen
The screen is the most important and at the same time the most fragile element of the smartphone, and in the diagnostic menu you will find a few items dedicated to the display, usually called "Display", "Touchpanel" or "Color Test", the first thing that is checked is the display of colors.
A color test can detect broken pixels or uneven backlights. The screen will be consistently painted red, green, blue, white and black. Carefully inspect the matrix at maximum brightness. Any extraneous spots, pink on white or black dots indicate a defect.
The next step is to check the touchscreen, where you fill the screen with a grid or a gray background, and you're asked to swipe your finger across the display, and the line that follows your finger should be flat and not interrupted, and if there's a line that breaks or twitches, it means that the sensor is not working properly in that area.
- 🔴 Red test: helps identify broken subpixels and red channel calibration problems.
- ⚪ White test: most effective for looking for uneven backlights and yellow spots.
- 👆 Multi-touch: Testing the screen’s ability to recognize multiple touches at the same time, which is critical for gaming.
☑️ Screen check
Special attention should be paid to the edges of the screen. Often, at the interface of the glass and the frame, the sensor may be "glutting" or not responding to pressing, and also check the automatic brightness adjustment, if such a test is provided in your version of the menu.
Checking of sound system and microphones
Xiaomi’s modern smartphones feature a sophisticated acoustic system that includes a main speaker, a conversational speaker, and several noise-canceling microphones, and are divided into separate items in the diagnostic menu: Speaker, Receiver, and Main Mic/Sub Mic.
When you test the speakers, it plays the melody. It's important to evaluate not only the volume, but also the purity of the sound. Wheezing, rattling or croaking at high frequencies indicate mechanical damage to the speaker or factory defect. The speaker is checked separately, the sound from it must be quiet but clear.
Checking the microphones is a critical step, and the menu will ask you to write down a short audio clip, say any phrase, and then play it back. The main problem with budget and medium-sized models is quiet recording or static noise, and if you can't hear the other person, the problem is often the software setup or malfunction of the microphone.
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When checking the microphone, cover the bottom hole (main microphone) and the top hole (noise reduction) in turn during recording, which will help you to understand which microphone is not working if the sound is lost.
Remember to check the vibrator. The vibrator makes the device vibrate. Estimate the vibration force: it should be palpable, but not rattling. Weak vibration can be a sign of wear or problems with the contact of the plume.
Camera testing and flashes
The camera is one of the main arguments when buying a smartphone, and the engineering menu divides the testing of cameras into several items: "Back Camera", "Front Camera" and "Flash", which allows you to check each module separately.
When you select the main camera checkpoint, the viewfinder will open. Take a few pictures, check zoom and autofocus. Point the camera at text or a fine pattern: if the image is floating or the focus cannot be brought (“breathes”), this is a sign of malfunctioning of the autofocus module or contamination of the lenses inside.
The flash is tested separately, it should be bright, even, flashing or dim lights indicate power problems in the module, and the front camera is also checked, which is especially important for video calls.
| Component | What we check. | Sign of malfunction |
|---|---|---|
| Main camera. | Focus, color reproduction, zoom | Blurring, black spots, shaking |
| Front camera. | Clearness, angle of view | Noise, purple hue |
| Outbreak. | Brightness, stability | Blinking, dim lights |
| Video | Stabilization, sound. | Sniffles, no sound |
Make sure to take a short video and check if the sound is recorded. It's often the camera is perfectly working and the microphone is silent when the video is recorded, it's a software bug or driver conflict that also requires attention.
Sensors and wireless modules
The smartphone is packed with sensors that make it comfortable to use, and in the diagnostics menu, you'll find tests for the accelerometer, the gyroscope, the proximity and light sensor, which are responsible for turning the screen around, adjusting the brightness, and turning off the display during a conversation.
The proximity sensor test looks like a bar of numbers. Hold your hand to the top of the screen, the values should change and the screen will go out. If that doesn't happen, you'll accidentally turn on the speaker or dial the number with your cheek.
A separate section is dedicated to wireless modules: Wi-Fi, Bluetooth and GPS. You can start searching for available networks and devices. If the phone does not see any Wi-Fi networks or GPS satellites, although they are available on other devices, the problem may be in the antenna module.
⚠️ Attention: Test GPS It's better to be outdoors or at a window, and inside a windowless room, the satellites may not be caught, which is not a malfunction of the phone.
Also, NFC is checked (if the module is in the model), the phone will try to read the tag or emulate the card, which is an important feature for contactless payment, so you should not ignore it.
Hardware buttons and connectors
Physical wear and tear of buttons is a common problem with smartphones, and the diagnostic menu has a "Key" or "Buttons" item, and the system will ask you to press each button: up volume, down volume, and power button.
The buttons must respond clearly, the first time, without sticking. If you need to press hard or multiple times to activate a function, the button contact group is worn out.
Separately, the connectors are checked. The Charger will show the status of the charger connection. Insert the cable - the phone should determine the type of connection (USB, fast charging). Checking the headphone jack (if any) will confirm the presence of an audio signal when you connect the headset.
Remember to check the fingerprint scanner if it's embedded in a screen or button. In the test, you'll need to apply your finger and make sure that it unlocks instantly. Delay or multiple attachments indicate a problem.
Results analysis and conclusions
After passing all the tests (manual or automatic), the system will produce a final report, usually a list marked "Pass" (successful) or "Fail" (error), and if you see a red "Fail" mark, it is a direct signal of the fault of the corresponding component.
However, even if all tests are successful ("All Pass"), it does not give a 100% guarantee of perfect performance in real-world conditions.
⚠️ Do not panic if one of the tests is done (for example, GPS or compass) emits an indoor error, calibration of some sensors required by the external conditions.
If you find a defect on a new device, take screenshots of the test results immediately, which will be a powerful argument when contacting a service center or a seller to return the goods under warranty.
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Regular diagnosis through CIT-The menu helps to identify hidden defects immediately after purchase, which makes it easier to return or warranty repair the device.