How to check memory on Xiaomi Mi 9: RAM, ROM and hidden errors

Xiaomi Mi 9 — flagship 2019 year-on-year 6/8 GB of RAM and 64/128/256 GB ROM, but even it can have memory problems over time: sudden reboots, brakes when multitasking or file writing errors. 80% It is not the fault of optimization. MIUI, a hardware defects of memory modules or wear of the flash drive. This article will help diagnose memory on Mi 9 without disassembling the device - from standard tools to professional tests through ADB.

We will discuss 7 working methods, from built-in MIUI features to third-party utilities and hidden engineering menus, and focus on diagnosing eMMC errors, which often appear on smartphones older than 3 years and can lead to data loss. If your Mi 9 becomes “glut” after an update or drop, these instructions will help identify the cause before visiting the service center.

1. Memory check through standard MIUI settings

So, to start with, the simplest of them all, the built-in MIUI tools, which don't provide deep diagnostics, but they show basic information about memory status and warn you of critical errors.

Open Settings → About the phone → Memory. Here you will see:

• 📱 Total ROM (e.g. 128 GB) and available space.
• 🔄 Memory state: If there is an exclamation point next to the inscription, it is a signal of problems with the flash drive.
• 📊 RAM usage: If less than 1 GB is free with closed applications, memory leakage is possible.

Pay attention to the Warehouse section → If it displays an unknown partition or less than the stated memory (for example, 112 GB instead of 128 GB), this may indicate that the data is not available:

• 🛠️ Hardware wear and tear eMMC/UF (typical of devices with intensive use).
• 🔧 Markup errors after incorrect update or reset.

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If the Memory section displays a message "Check the drive," that's the first sign that the flash memory is starting to degrade.

2. Hidden Engineering Menu: Memory Test (#4636##)

The Xiaomi Mi 9 has a hidden menu for diagnosing hardware components, including memory.

1. Open the Phone app.
2. Enter the combination: ##4636###.
3. Select the Testing (testing) item.

This menu is available:

• 🧠 RAM Test – checking RAM for read/write errors.
• 💾 Storage Test – Flash memory test (can take 5-10 minutes).
• 📶 Modem Test – indirectly affects memory performance when working with the network.

If you see a FAIL message next to RAM or Storage after the test, it means:

⚠️ Note: Mi 9 with older firmware MIUI 12.5 The memory test in the engineering menu may give false positives due to the limitations of the core.

3. Diagnosis through ADB: Professional Analysis

For deep memory check, you will need ADB (Android Debug Bridge), which is suitable if:

• 🔍 You suspect hardware defects (for example, broken sectors in ROM).
• 🛠️ Standard tests show no errors, but the smartphone slows down.
• 📉 You want to check the read/write speed of flash memory.

Instructions:

1. Enable USB Debugging in Settings → About Phone → MIUI version (click 7 times, then go back to Additional → For Developers).
2. Connect the Mi 9 to your PC and confirm the debugging permission.
3. Open the command line and enter:

adb shell


cat /proc/meminfo | grep -i "memtotal\|memfree"




df -h /data




dd if=/dev/zero of=/sdcard/testfile bs=1M count=512

Transcript of commands:

• cat /proc/meminfo – will show the total amount of RAM and free memory.
• df -h /data - displays the state of the /data partition (where applications are stored).
• dd if=/dev/zero... – a recording test (if the command ends with an error, there are problems with ROM).

4. Applications for memory testing: top-3 utility

If you are uncomfortable with ADB, you can use third-party apps. We tested 10 utilities and selected the 3 most accurate for Xiaomi Mi 9:

For the Mi 9, we recommend starting with the A1 SD Bench, as memory problems on this device are more often associated with eMMC degradation (write speed falls below 50 MB/s). If the read speed is below 200 MB/s and the write speed is below 100 MB/s, this is a sign that the flash memory is worn out.

Charge your phone at least 50%

Connect to Wi-Fi (to download tests)

Make a backup copy of important data

Turn off the power saving modes-->

5. Checking for broken sectors: method with a marker file

If your Mi 9 suddenly reboots or forgets files, it may have broken sectors in the ROM.

1. Create a file size of 1-2 GB on internal memory (for example, through the File Manager application).
2. Copy it into another folder.
3. Compare checksums (MD5) of the original and the copy using the Hash Droid app.

If the checksums do not match, this means:

• 🚨 Flash memory is degraded (typical for devices with eMMC 5.1, as in the Mi 9).
• 🔧 Possible file system errors (will help reset to factory settings).

⚠️ Note: Xiaomi Mi 9 with firmware MIUI 13+ This can be used to protect against writing large files to the root folders. Use the Download folder or external folder for the test. SD-card (if supported).

6. Diagnostics via Fastboot mode (for power users)

If the phone doesn't turn on or is constantly rebooted, a memory check can be done via Fastboot.This method requires a PC and command line knowledge.

Instructions:

1. Turn off the Mi 9 and press Power + Volume down to enter the Fastboot.
2. Connect your phone to your PC and type a command:

fastboot devices


fastboot oem diag




fastboot oem test_memory

Transcription of results:

• PASS - Memory's fine.
• FAIL [ERROR_CODE] — Memory error (code can be decrypted via Qualcomm documentation).
• NOT_SUPPORTED — Your version of Fastboot doesn't support the test (update the Mi Flash Tool).

If the test shows an error, try flashing your phone through Mi Flash with the clean all option, which solves memory problems caused by a firmware failure in 60% of cases.

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Memory test via Fastboot is the only way to diagnose hardware errors on a broken Xiaomi Mi 9. If the fastboot oem team test_memory return FAIL, It will probably require a replacement motherboard.

7.When to contact the service: signs of critical malfunctions

Not all memory problems can be solved software.

• 🔄 The phone is cyclically restarted (especially when loading heavy apps).
• 📉 Record speed drops below 30 MB/s (checked through the A1 SD Bench).
• 🚫 The system does not see part of the memory (for example, 32 GB is displayed instead of 128 GB).
• 🔥 The phone overheats in the processor area for simple tasks (may indicate memory controller overload).

The average cost of memory repair on Xiaomi Mi 9 (2026)

• 🔧 Replacement eMMC/UF-storage: 3 500–6 000 ₽ (volume-dependent).
• 🖥️ Memory controller repair: 5,000–8,000 ₽.
• 🔄 Flashing with partition restoration: 1,500–2,500 ₽.

⚠️ Note: Mi 9 with Samsung memory modules KLUDG8U1ED-B0D1 (128 GB) is often a defect of "disappearing memory" after 2-3 years of use, it is a fault of the controller, and it can not be fixed software.

FAQ: Frequent questions about memory check on Xiaomi Mi 9