Many smartphone owners notice in the list of applications or when entering special codes an item called Auto Test or HWTest. A logical question immediately arises: auto test what is it on Android is this a virus or a hidden security threat? In fact, this is a built-in system tool designed to deeply diagnose the hardware of your device.
This mode allows engineers and advanced users to test the functionality of each physical component of the phone without having to disassemble the case or connect third-party equipment. You will be able to independently evaluate the quality of the sensor, the performance of the microphones, the correct display of colors on the matrix, and even check the proximity sensors, which often fail.
Access to this functionality is usually hidden from the average user to avoid accidental changes to settings or panic when seeing technical data. However, knowing the correct sequence of actions, you can turn your smartphone into a professional diagnostic tool right in your hands.
The essence of the automatic testing mode
Under the term Auto Test means a set of scripts and software modules that sequentially poll equipment controllers. Unlike simple applications from the store, which only read superficial data, this mode forces the hardware to work in certain load modes.
For example, when testing the screen, the system alternately floods the display with red, green and blue, identifying dead pixels or uneven backlighting. When checking the touchscreen, you are asked to slide your finger along special lines, and the system records each contact with mathematical precision.
It is worth noting that the names of this menu may differ depending on the firmware manufacturer. On devices Samsung this is often called Device Care or hidden in the engineering menu, and on Xiaomi and Redmi it is known as CIT (Calibration and Test). But the essence remains the same - checking the physical integrity of the components.
⚠️ Attention: Some tests in this mode may lead to a device reboot or sensor calibration reset. Do not press the “Pass” or “Fail” buttons if you are not sure of the result of testing a specific module.
Before running a full cycle of tests, make sure that the battery charge is at least 30%, since some tests (for example, flashes or vibrations) consume a lot of energy.
How to enter the engineering menu and start verification
The most common way to activate diagnostics is to use special USSD codes, which are entered through the standard “Phone” application. These combinations work on most devices running pure Android, as well as on shells MIUI i OneUI.
First, open the “dialer” and enter the following sequence of characters: ##4636##. If the code is correct, the menu will open instantly, without having to press the call button. On some models, especially from Samsung, a code #0#may work, which immediately starts a visual test of components.
If standard codes do not work, try the universal option for many Chinese brands: ##6484## or ##64663##. In rare cases, access to these functions may be blocked by the telecom operator or the firmware itself.
After entering the menu, you will see a list of available tests. Select the item Auto Testif it is in the list, or run component checks individually. The system may request permission to access some functions, which must be confirmed.
Main types of available hardware tests
The diagnostic menu interface is usually divided into logical blocks. Each block is responsible for a specific subsystem of the smartphone. Understanding what exactly is being checked will help you correctly interpret the results.
Here are the main categories of checks that you will encounter most often:
- 📱 Display & Touch: Checking the matrix for dead pixels, backlight uniformity and sensitivity of the touch layer.
- 🎤 Audio & Mic: Testing the main and additional microphones, earpiece and polyphonic speaker.
- 📡 Sensors: Diagnostics of the accelerometer, gyroscope, light and proximity sensor.
- 🔋 Power & Battery: Checking the voltage, temperature and condition of the battery, as well as the operation of the charge controller.
- 📶 Connectivity: Test of Wi-Fi, Bluetooth, GPS and cellular modules.
Particular attention should be paid to sensor testing. Often, it is malfunctions in the accelerometer that lead to the screen not rotating, and problems with the proximity sensor cause the screen to go dark during a call.
What is Loop Test?
Loop Test is a mode of endless cyclic repetition of all checks. It is used in factories to identify “floating” defects that appear only after the device is heated.
Step-by-step guide for checking the display and sensor
Checking the screen is one of the most important procedures, especially when buying a used device or after a smartphone has been dropped. Matrix malfunctions may be barely noticeable against a normal background, but are critical when watching a video or reading text.
To run the test, find the item LCD or Display Testin the menu. The screen will begin to change colors. Carefully inspect the surface: black dots on a white background or colored spots on a black background indicate pixel defects.
Next is a check of the touchscreen. Usually a grid or pattern appears that you need to drag your finger across. The lines should be colored exactly the moment you touch them. If there are breaks in the drawing of lines in certain areas, it means that the sensor is “dead” in this place.
| Test type | What we check | Normal result | Symptoms of malfunction |
|---|---|---|---|
| Red/Green/Blue | Matrix | Umogeneous color without spots | Dead pixels, glare |
| Touch Draw | Sensor | Continuous line | Gaps, "jitter" cursor |
| Vibration | Vibration motor | Clear vibration | No response, crackling |
| Proximity | Proximity sensor | Value 0.0 when closing | Constant value 5.0 |
If you find problems with the sensor, first try wiping the screen and removing the protective glass. If this does not help, you will most likely need to replace the digitizer.
⚠️ Attention: Do not try to calibrate the sensor through the engineering menu if you do not know the exact values. Incorrect calibration can make part of the screen completely insensitive.
Matrix defects (dead pixels) are physical damage and cannot be eliminated by a soft reset or flashing the device.
Diagnostics of the audio system and microphones
Sound problems are one of the most common reasons for contacting the service. In Auto Test mode you can test each sound source in isolation. This helps to understand whether the problem is in the dynamics, in the software or in dirty grids.
Run the test Speaker or Receiver. The device will start playing the melody or noise at maximum volume. Listen: the sound should be clear, without wheezing, crackling or extraneous sounds. Distortion often indicates that the speaker membrane is torn or peeled off.
To check microphones, select item Microphone. You will be prompted to say something or make a sound. The system will record it and play it back immediately. If you hear silence or loud noise instead of your voice, the microphone is faulty.
Modern smartphones have several microphones: the main one (at the bottom), an additional one (at the top for noise reduction) and the one built into the camera. Make sure that all options available in the menu have been tested.
☑️ Sound check checklist
Checking sensors and communication modules
The operation of navigation and automatic brightness depends on many small sensors. In diagnostic mode, you can see their current readings in real time, which is impossible to do through normal settings.
Find the section Sensor. Turn the phone in different directions - the accelerometer and gyroscope values should change smoothly. Cover the top of the screen with your hand - the proximity sensor should change its state from Far (far) to Near (close).
Tests for communication modules are also available. When checking Wi-Fi i Bluetooth the system will try to turn on the module and search for available devices. If the scan does not start or gives an error, the antenna cable may have come loose or the chip has failed.
To check the GPS, you will need to go outside or go to a window. The system will show the number of visible satellites and try to determine the coordinates. A long absence of signal in a clear sky indicates a problem with the GPS antenna.
⚠️ Attention: Tests of communication modules (Wi-Fi, Bluetooth, GPS) may not work correctly if the signal in the room is poor or there is strong radio interference.
Why is the light sensor important?
If this sensor is broken, the phone will not be able to automatically adjust the screen brightness, which will lead to rapid battery drain or eye discomfort.
Interpretation of results and further actions
After passing all tests, the system usually issues a summary report or simply marks each item with a checkmark (Pass) or a cross (Fail). However, even if the test is passed, your personal feelings may suggest otherwise.
If you have identified a malfunction, first try a soft reset (not to be confused with a full factory reset, although this is sometimes required). Often, failures in the operation of sensors are caused by a software conflict.
In the case when software methods do not help, but the test Auto Test confirms a hardware problem, you need to contact a service center. The data obtained in this mode can be a strong argument for recognizing the case under warranty.
Remember that the interfaces and available functions may vary slightly depending on the version Android and the specific device model. Manufacturers regularly update diagnostic utilities.
⚠️ Attention: Menu details and access codes may change with firmware updates. If the code does not work, check the latest information for your specific model on the manufacturer's official website.
Regular diagnostics through Auto Test helps to identify incipient problems with the battery or sensor before they become critical.
Is it safe to use engineering menu codes?
Yes, using codes to view information and run tests (#0#, ##4636##) is safe. The only danger is the “Write” or “Set” section, where you can change the IMEI or frequencies of the radio module. Do not change the values if you do not know what they are responsible for.
Why does the code #0# not work on my phone?
This code is a proprietary development Samsung. On phones Xiaomi, Huawei or Pixel other combinations are used (for example, ##6484## for Xiaomi). Also, the code may be blocked by the telecom operator.
Is it possible to find out the actual wear of the battery through Auto Test?
Indirectly - yes. In the Battery section you can see the current voltage and temperature. However, it is better to view the exact percentage of wear (SOH) through specialized applications like AccuBattery or in the engineering menu through the command adb.
What to do if the sensor test shows gaps?
First, remove the protective glass and film, wipe the screen. If the gaps remain in the same places, the display cable or the digitizer itself is probably damaged. The screen assembly needs to be replaced.
Does Auto Test reset your phone settings?
No, the testing process itself does not change your personal data, photos or system settings. However, some tests may temporarily change the screen brightness or sound volume to the maximum.