How to make a Xiaomi phone diagnosis at home: from battery to sensors

Your Xiaomi is slowing down, running out, or acting weird? Don't rush it to the service center -- most problems can be detected by using built-in tools and simple tests. In this article, we'll look at how to check all the key components of a smartphone, from the battery to the NFC module, without having to disassemble the device.

Diagnostics at home will save time and money, and give a clear understanding of what is wrong with your Redmi, POCO or Mi. We will look at both standard methods (hidden menus, USSD codes) and third-party applications with detailed reports.

All instructions are valid for MIUI 12-14 and HyperOS devices, including the 2020-2026 models. If your phone is released earlier, some menu items may differ - but the overall logic of the check remains the same.

1. Quick check through secret USSD codes

The easiest way to get basic information about the condition of the phone is to use engineering codes, which work on all Xiaomi smartphones without installing additional programs, just open the Phone app and type in the combination as if you were calling.

Here are the basic codes and what they show:

• 📱 ##4636## - information about battery, network usage, Wi-Fi statistics. MIUI This code may be blocked.
• 🔋 ##2846579## → ProjectMenu → Background setting → Battery log - detailed battery discharge statistics (only for some models).
• 📡 ##232338## — MAC-Wi-Fi address, connection information.
• 📞 ##2663## - The touchscreen firmware version (useful if the screen does not respond well to touches).

If nothing happens after you enter the code, Xiaomi has blocked this method for your model, in which case move on to the next section with alternative methods.

⚠️ Warning: Do not enter codes found on questionable forums - some combinations (e.g. ##7780##) can reset your phone to factory settings.

2. Battery check: capacity, wear and charging speed

The battery is the weakest component of a smartphone, and even if a new, incorrect charge or overheating can shorten its lifespan, to check the battery status on Xiaomi, do the following:

1. Go to Settings → Battery and Performance → Battery status. This shows the current capacity (e.g., "3900 mAh out of 4000 mAh"). If the difference is greater than 10%, the battery is worn out.
2. Install the AccuBattery app (free on Google Play) and it will show the wear rate, the temperature during charging and the actual charge rate.
3. Check how fast the phone is running on standby: Charge to 100%. Turn off mobile data, Wi-Fi, Bluetooth. Leave for 8 hours. Normal consumption is no more than 5% per night.

If the battery is discharged too quickly, the reasons may be different:

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If the phone turns off at 10-20% charge, calibrate the battery: discharge to 0%, charge to 100% without interruptions, repeat 2-3 times.

3. Screen testing: dead pixels, color reproduction, touchscreen

Xiaomi’s screen problems range from broken pixels to “ghost” touches. To check the display, follow these steps:

1. Visual examination: 🔍 Turn on a white background (open notes or a browser with a blank page). Light up with a flashlight at an angle so you can see scratches and stains better. 🎨 Check the color rendering: open the image with a gradient (for example, the Lagom test.
2. The broken pixel test: Use the Screen Test app (or Dead Pixel Test) to alternately color the screen in different colors, so you see the dots that are not working.
3. Touch screen check: Open Settings → About Phone → MIUI version and quickly press 5 times on the Core (CTS menu will appear). Select Touch Screen Test - draw lines throughout the screen. If the lines are interrupted, the sensor is faulty.

Typical Xiaomi screen problems and their causes:

• 🖥️ Yellow color: often found on the AMOLED-screens (Redmi) K50, POCO F4). It is a feature of the matrix, not marriage.
• ✋ "Ghost" touches: caused by a plume damage or moisture ingress.
• 🔄 Screen flicker: maybe because of automatic brightness. Turn it off in Settings → Display. → Automatic brightness.

4. Diagnostics of speakers, microphone and connectors

Xiaomi's audio problems fall into two categories: software (settings, drivers) and hardware (damaging speakers, microphones or audio chips).

1. Dynamics: 🔊 Turn the music on at maximum volume. The sound should be clear, without wheezing. Check both speakers (top and bottom) if there are any. 🎵 Use a bass test file (e.g. audiocheck.net) If the bass is missing, the speaker is damaged.
2. Microphone: 🎤 Write down a voice message on WhatsApp or a voice recorder. Listen, your voice needs to be clear, no noise. 📞 Call another phone and check how you can be heard.
3. Connector. Type-C/3.5 mm: 🔌 If the sound is interrupted or missing in one ear, the problem is the connector or plug. 🔋 Check charging through this connector – if the phone isn’t charging, the contacts are contaminated or damaged.

If there's no sound at all:

⚠️ Note: Some Xiaomi models (Redmi Note 11, POCO X3 Pro) after the update, the sound in the speaker disappears. This is treated by resetting the settings → System system → Resetting settings → Reset all settings (data will not be deleted).

For a deep diagnosis, install Phone Doctor Plus, which will test all audio components and show if each one works.

5. Camera check: focus, stabilization, sensors

Xiaomi cameras are known for their quality, but they can also fail. Frequent problems: blurry images, artifacts in the photo, broken stabilization.

1. Main camera test: 📸 Take a picture of text from 30 cm away. All letters should be clear. If the text is blurred, it's a problem with focus. 🌃 Take a picture of a dark room. The picture should not have green/purple spots (this is a matrix defect).
2. Front camera: 🤳 Take a selfie with Beauty on and off (in camera settings). If you don't have filters, your face is blurry, the camera is defocused.
3. Additional modules (ultrashir, macro, telephoto): 🔍 Switch to macro mode and take a picture of a small object (like a coin. 🏔️ In ultra-wide mode, check if there are any distortions at the edges (this is the norm for cheap models, but not for flagships).

If the camera is not focusing:

• 🛠️ Clean the lens with a soft napkin (sometimes it is enough to remove dirt).
• 🔄 Restart your phone – sometimes the camera driver crash fixes this way.
• 📱 Install the Manual Camera (from Google Play) and try to manually adjust the focus. If it doesn't work, the module is faulty.

The camera doesn't work at all?|There are physical injuries (cracks, dents)?|The problem is evident in all applications (not just in the standard camera)?|You tried resetting the camera settings?-->

6. Testing of sensors: gyroscope, accelerometer, NFC

Xiaomi has a lot of sensors on its smartphones that make games, navigation and contactless payments work, and check them in order:

1. Gyroscope and accelerometer: 🎮 Install the Sensor Test (or AndroSensor) and check the Gyroscope and Accelerometer. 📱 Turn Level on in the standard Compass app. Put your phone on a flat surface, and the bubble should be centered.
2. Approximation sensor: 📞 When you call, put your hand up to the top of the screen, the display should go out. If it doesn't, the sensor is defective or contaminated.
3. NFC: 💳 Turn it on. NFC In Settings → Connection and sharing → NFC. 🏦 Try to pay something through Google Pay or a bank app. If the payment doesn't pass, the chip NFC damaged.
4. Light sensor: ☀️ Turn on automatic brightness and cover the sensor (near the front camera) with your finger.

On the POCO F3 and Redmi K40, there is often a problem with the gyroscope after falls - the phone starts to "twitch" in games (for example, in PUBG Mobile), this is treated only by replacing the motherboard.

7. Check the network and communication modules (Wi-Fi, Bluetooth, GPS)

If your Xiaomi is not catching the network well, loses the connection to Wi-Fi or does not find GPS satellites, the problem can be both in settings and in hardware.

1. Mobile network (4G/5G): 📶 Go to Settings. → SIM-maps and mobile networks → Network type. Just choose. 4G (preferably 5G (if maintained). 📊 Check the speed of the Internet through Speedtest. 10 Mbps with a good signal – a problem with the operator or antenna of the phone.
2. Wi-Fi: 📶 Connect to a 5GHz network (if the router supports it) If the phone can't see it, the Wi-Fi module runs in a reduced mode. 🔄 Forget the network (Settings) → Wi-Fi → [tap the net] → Remove) and reconnect.
3. Bluetooth: 🎧 Connect your headphones or speaker. If the sound is interrupted, update your firmware or reset your Bluetooth settings (Settings) → Connection and sharing → Bluetooth → ⚙️ → Resetting settings).
4. GPS: 📍 Install. GPS Status & Toolbox and check how many satellites the phone finds — 8–12, open-air — 15+. 🗺️ Include High Accuracy in Settings → Location → Regime.

If the phone doesn’t catch the network at all:

• 🔧 Check if it's inserted. SIM-slot-card SIM 2 (only in some models it works with the 2G).
• 📱 Restart your phone in Safe Mode (press the power button) → Safe Mode: If the network is on, it's the third-party app's fault.

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If after the update the mobile network disappeared, reset the settings APN: Settings → SIM-maps and mobile networks → Access points (APN) → Reset to factory.

8. Full diagnostics through the engineering menu (MTK/Qualcomm)

For a deep analysis of hardware, you can use an engineering menu, the method depends on the processor of your Xiaomi:

• 🔧 For Qualcomm processors (Snapdragon): Enter the code ##225## or ##4636##. → Check all items (especially Audio, Sensors, Battery).
• 🛠️ For MediaTek processors (Helio, Dimensity): Enter #36446337## (or #4636## → Engineering Mode. Go to Hardware Testing → Single Item Test and select the desired component.

The engineering menu can:

• 📊 See the actual battery voltage (normal 3.7–4.2V).
• 🔊 Check the signal quality (Network item) → Serving Cell Info. Meaning RSRP should be higher -100 dBm.
• 📡 Identify problems with antennas (if you have a problem with the antennas) RX Level is constantly changing, perhaps the plume has gone away).