Most Xiaomi and Redmi users have no idea their phones come with a complete diagnostic laboratory built right in. I'm talking about secret codes special combinations you type into your dialer that unlock hardware tests, engineering menus, and troubleshooting tools that can save you a trip to the repair shop.
Here's the thing about Xiaomi phones: they're popular, affordable, and surprisingly feature-packed. But they also hide some of the most useful diagnostic tools I've seen in any Android brand. After years of working with everything from budget Redmi A-series to flagship Mi 13 Ultra and POCO F-series phones, I've learned these codes inside and out.
What makes Xiaomi codes particularly interesting is the CIT (Complete Internal Test) menu. It's basically a full hardware testing suite that Xiaomi uses in their factories. And guess what? You can access it too. No root, no special apps, just a simple code.
🔍 Must-Know Device Information Codes
*#06# - Your Phone's Identity Card
This one's universal, but it's the starting point for everything. Type it and boom your IMEI number appears instantly.
Why does this matter? Last week, someone on Facebook Marketplace tried selling me a Redmi Note 13 Pro at half price. "Urgent sale," they said. I typed *#06# right there, checked the IMEI on a blacklist database, and found out it was reported stolen. Saved myself from buying a phone that would've been blocked by carriers within days.
Your IMEI is your phone's fingerprint. It's unique to your device. You need it for warranty claims, insurance, carrier unlocking, and proving ownership. Take a screenshot now and save it somewhere other than your phone. Trust me on this.
*#*#64663#*#* - The CIT Menu (Xiaomi's Secret Weapon)
This is the code that separates Xiaomi from other brands. CIT stands for Complete Internal Test, and it's exactly what it sounds like every single hardware component can be tested here.
Type the code and you'll see a menu with options like Automatic Test, Single Item Test, and Test Report. Here's what each does:
Automatic Test: Runs through all hardware sequentially. Takes about 5 minutes. Perfect for quickly checking if a used phone has any obvious problems.
Single Item Test: This is where the magic happens. You can test individual components:
- Display: Shows solid colors (red, green, blue, black, white) to spot dead pixels or screen burn-in
- Touch: Draw on screen to check for dead zones. I once found a Redmi phone with an entire corner that didn't respond
- Multi-touch: Tests how many simultaneous touches your screen supports (usually 10 points)
- Flashlight: Cycles through LED brightness levels
- Cameras: Tests front and rear cameras, including all lens modules on multi-camera setups
- Vibration: Motor test at different intensities
- Speaker: Left and right channels separately (on stereo speaker phones)
- Receiver: Earpiece speaker test
- Mic: Records and plays back your voice
- Headset: Tests audio jack or Type-C audio (model dependent)
- Keytest: Tests volume and power buttons
- Bluetooth: Scans for nearby devices
- WiFi: Tests connection and signal strength
- GPS: Satellite detection and location accuracy
- Proximity: Tests the sensor near your earpiece
- Light: Tests ambient light sensor
- Gyroscope/Accelerometer: Motion sensor testing
- Magnetic: Compass sensor test
- Charging: Verifies charging circuit works
- SIM: Detects SIM cards in both slots
Test Report: Shows results from previous automatic tests. Green checkmarks mean pass, red X means fail. Simple as that.
I use this menu on literally every Xiaomi phone I consider buying used. It's caught fake cameras (yes, some phones have dummy camera modules that don't actually work), dead touchscreen zones, broken GPS chips, and more issues than I can count.
*#*#4636#*#* - Testing Mode (The Data Nerd's Dream)
This opens Android's hidden testing menu. It's not Xiaomi-specific, but it works on all their phones and gives you tons of useful info.
Phone Information tab: Shows your real signal strength in dBm (not those vague bars), network type, IMEI, and lets you run a ping test. You can also see your radio status and switch between network modes.
Here's the reality of signal bars: "3 bars" on one phone might be -85 dBm while "3 bars" on another is -95 dBm. That's a huge difference. This menu shows the actual numbers. Anything better than -85 dBm is solid. Below -100 dBm and you'll notice issues.
Usage Statistics: Want to know which apps are actually draining your battery? This shows real usage data, not guesses. I found out that a "battery optimizer" app was ironically the biggest battery drain on someone's Redmi Note 12.
WiFi Information: Deep dive into your WiFi connection status, speed, and technical details.
*#*#6484#*#* - Hardware Detection Menu
Another diagnostic menu, similar to CIT but with a different interface. Some Xiaomi models respond better to this code than the CIT code. Try both and see which gives you more options.
🔧 Engineering Mode & Advanced Testing
*#*#3646633#*#* - MTK Engineering Mode
This only works if your Xiaomi/Redmi phone has a MediaTek processor. Most budget Redmi phones (Redmi A-series, some Note series) use MTK chips.
Engineering mode is powerful but dangerous. You can access detailed hardware info, network band selection, audio profiles, and RF calibration. The problem? Change the wrong setting and your phone might not boot, or worse no network connectivity at all.
Safe things to look at: battery info, sensor data, network information. Unsafe things to touch: RF calibration, network mode changes, audio routing (unless you're following a specific fix guide).
I've seen people brick their Xiaomi phones by randomly changing engineering mode settings. Curiosity is great, but this menu requires knowledge. Look, don't touch.
*#*#7262626#*#* - Field Test Mode
Shows real-time cellular network information. Great for troubleshooting signal issues or verifying which bands your phone is connecting to.
🔋 Battery Health & Power Diagnostics
Battery Test (via CIT Menu)
In the CIT menu (*#*#64663#*#*), there's a battery section that shows way more detail than MIUI's built-in battery settings.
Info displayed:
- Current temperature (normal is 25-35°C)
- Voltage (healthy range: 3.7V to 4.2V)
- Charging status and current (in milliamps)
- Battery health percentage
- Charge cycle count
Quick health check: If your battery health is below 80%, it's time for a replacement. If temperature stays above 40°C when idle, either you have a rogue app eating CPU, or the battery is degrading.
Real example: Friend complained his POCO X5 barely lasted half a day. CIT battery test showed 68% health with 912 cycles. He'd been using it heavily for almost 2 years. New battery cost $15 and fixed everything. No need for a new phone.
*#*#0842#*#* - Backlight/Vibration Test
Quick 10-second test. Screen dims and brightens while vibration motor pulses. Good for checking if both systems work properly without opening full diagnostic menus.
📡 Network & Connectivity Testing
Network Mode Selection (*#*#4636#*#*)
In the Phone Information section, there's a dropdown to select preferred network type. This is actually super useful:
LTE only: Forces 4G connection. Use this when you're in an area with solid 4G but your phone keeps dropping to 3G. Saves battery too since it stops searching for 5G.
LTE/3G: Allows fallback to 3G in weak 4G areas. Good balance for most situations.
3G only: When 4G signal is so weak it's unusable, forcing 3G often works better.
2G only: Emergency mode. 2G is slow but has the longest range. Last resort for connectivity.
I used this when visiting my parents' village. Phone kept switching between weak 4G and 3G, burning battery. Forced it to 3G-only and suddenly had stable connection all day.
WiFi & Bluetooth Tests (CIT Menu)
WiFi test scans for networks and measures signal strength. Bluetooth test searches for nearby devices. Both verify the radios work properly essential after water damage or repairs.
📱 MIUI & Software Information
*#*#1234#*#* - Software Version Details
Shows your complete software setup: MIUI version, Android version, security patch date, baseband version, kernel info.
Before downloading Xiaomi firmware from MobiFirms, check this. You need the exact model number and current software version. Flash the wrong ROM and you'll end up with a brick.
Pro move: Screenshot this screen and keep it saved. If you ever need to restore your phone to factory state, you'll know exactly which firmware to download.
*#*#86#*#* - MIUI Version Checker
Quick way to see your MIUI version without digging through settings. Some models require you to press call after typing.
📸 Camera Testing & Multimedia
Camera Tests (CIT Menu)
Camera section in CIT menu tests each camera module individually. On phones with quad cameras, you can test main, ultra-wide, macro, and depth sensors separately.
Look for these red flags:
- Autofocus that hunts back and forth without locking (lens actuator problem)
- Purple or green tint in photos (sensor damage from heat or drop)
- Camera app crashes when switching lenses (software bug or fake camera module)
- Blurry photos that can't focus at any distance (damaged lens)
Fun fact: Some ultra-budget Xiaomi phones have "camera" bumps that are just decorative. The CIT test will show which cameras actually work versus which are dummy modules for aesthetics.
Audio System Tests
Speaker test plays tones through each speaker. Listen carefully:
- Crackling or popping = damaged speaker cone
- Low volume at max = clogged speaker grille (often just dust)
- Imbalanced stereo = one speaker failing
Mic test records your voice and plays it back. If it sounds muffled, check for blocked microphone holes. If it's distorted, the mic itself might be failing.
🗺️ GPS & Location Testing
GPS Test (CIT Menu)
GPS section shows satellite detection in real-time. Good phone should detect 8+ satellites within 30 seconds outdoors with clear sky view.
What to check:
- Satellite count (more is better, 8+ is good)
- Signal bars for each satellite (should have multiple with strong signal)
- Time to first fix (under 60 seconds is normal)
- Location accuracy (5-10 meters is good, 30+ meters indicates problems)
No satellites detected at all? GPS antenna might be disconnected. This often happens after screen replacements when technicians forget to reconnect the antenna cable. Five-minute fix if you know what you're doing.
🔐 SIM & Network Lock Status
Checking Lock Status
Xiaomi doesn't have a dedicated SIM lock code like some brands. Easiest way to check: try a SIM from a different carrier. If it works, phone is unlocked. If it asks for an unlock code, it's carrier locked.
Secret codes can't unlock carrier-locked phones. They can only check status. For actual unlocking, contact your carrier or use professional services.
Buying used Xiaomi internationally? Always verify it's unlocked before purchase. Some phones sold in specific countries (especially Russia or China) are locked to local carriers and won't work elsewhere.
🔄 Factory Reset Options
*#*#7780#*#* - Factory Data Reset
What gets deleted: Every app, all data, Google account info, WiFi passwords, Bluetooth pairings, photos not backed up to cloud, contacts, messages, everything.
What stays: MIUI version, system apps, whatever's on your SD card (if you have one).
When do I use factory reset? When a phone is so messed up constant crashes, freezing, bootloops that nothing else works. It's the nuclear option that solves about 85% of software problems.
Major warning: Factory reset does NOT remove FRP (Factory Reset Protection). After reset, you MUST log in with the previous Mi/Google account. Buying a used phone? Make the seller remove their accounts BEFORE you factory reset, or you'll be locked out permanently.
Safer Method
Settings → About Phone → Backup & Reset → Factory Reset. This gives you warnings and backup options. Much safer than the code.
🎯 Complete Code Reference
Essential Codes
- *#06# - Display IMEI number
- *#*#64663#*#* - CIT menu (hardware tests)
- *#*#4636#*#* - Testing mode
- *#*#6484#*#* - Hardware detection
- *#*#3646633#*#* - Engineering mode (MTK only)
- *#*#7262626#*#* - Field test mode
- *#*#1234#*#* - Software version
- *#*#86#*#* - MIUI version
- *#*#0842#*#* - Backlight/vibration test
- *#*#2664#*#* - Touch screen test
- *#*#0588#*#* - Proximity sensor
- *#*#7780#*#* - Factory reset (CAREFUL!)
Quick Test Codes
- *#*#0*#*#* - LCD test
- *#*#232338#*#* - WiFi MAC address
- *#*#1472365#*#* - GPS test
- *#*#232331#*#* - Bluetooth test
- *#*#526#*#* - WLAN test
- *#*#8255#*#* - GTalk service monitor
💡 What I've Learned Testing Hundreds of Xiaomi Phones
Why Codes Sometimes Don't Work
MIUI version restrictions: Xiaomi has been slowly restricting diagnostic access with each MIUI update. MIUI 12 had almost everything working. MIUI 13 removed some features. MIUI 14 locked down even more. Your shiny new Redmi Note 13 Pro with MIUI 14 might not support codes that worked perfectly on an older Redmi Note 10 with MIUI 12.
Regional firmware differences: Chinese ROM (China) vs Global ROM vs Indian ROM they all handle diagnostic codes differently. Chinese ROM typically has the most features unlocked. Indian ROM is in the middle. Global ROM is most restricted.
Custom ROM effect: If you flashed a custom ROM or modified system, some codes might not work at all. Stock MIUI works best.
Must use stock dialer: Third-party dialers like Google Phone or Truecaller can't execute secret codes. You need Xiaomi's default blue phone icon app.
My Testing Routine for Used Xiaomi/Redmi Phones
When evaluating phones for purchase or diagnosing issues:
- IMEI check (*#06#) - Verify on online databases for blacklist/stolen status
- Run CIT automatic test (*#*#64663#*#*) - Catches 90% of hardware issues in 5 minutes
- Manual test failed items - If automatic test shows red X on any component, test it manually
- Battery health check - Look for temp issues and cycle count
- GPS satellite test - Should lock within 60 seconds outdoors
- Check signal strength (*#*#4636#*#*) - Verify dBm is reasonable
- Document software version (*#*#1234#*#*) - Screenshot for future reference
- Physical inspection - Water indicators, screen condition, port damage
This takes 15 minutes max but has saved me from buying phones with hidden problems more times than I can count. One time found a "mint" POCO F5 that had zero GPS function the CIT test caught it immediately while the seller stood there confused about why I wouldn't buy it.
Most Useful Discoveries
The CIT menu is gold: Having every hardware test in one place, official from Xiaomi, means I don't need third-party testing apps that might be sketchy or inaccurate.
Signal strength numbers changed everything: Before I knew about dBm readings, troubleshooting "bad signal" was guesswork. Now I can tell customers "you're at -103 dBm here, that's why calls drop" with actual data.
Battery health truth: MIUI's battery settings are way too optimistic. CIT menu shows real health. I've seen MIUI claim "Good battery health" on batteries at 71% capacity according to CIT diagnostics.
🔗 Essential Xiaomi Resources
📥 Xiaomi/Redmi Firmware Downloads - Official stock ROM files for all models: Redmi Note 13, POCO X6, Mi 13, and hundreds more. Tested firmware with flashing guides included.
🛠️ Flash Tools & Software - Get Mi Flash Tool, QFIL, SP Flash Tool, and other essentials for flashing Xiaomi firmware. Complete driver packages and setup instructions.
🔓 FRP Unlock Tools - Locked out after factory reset? Professional tools and guides to bypass Mi Account and Google FRP protection legally and safely.
📱 Firmware Library - Not just Xiaomi official firmware for Samsung, Vivo, Oppo, Realme, Tecno, Infinix, and all major brands. All tested and verified.
📖 Android Repair Guides - Step-by-step tutorials for unbrick, IMEI fix, bootloop solutions, EDL mode flashing, and professional repair techniques.
❓ Common Questions About Xiaomi Secret Codes
Can these codes damage my Xiaomi phone?
Information codes (*#06#, *#*#64663#*#*) are totally safe. They just display info or run tests. Factory reset code wipes data but won't brick your phone. Only engineering mode (*#*#3646633#*#*) has potential for problems if you change RF or network settings without knowing what you're doing. But even then, flashing stock firmware fixes it. Stick to diagnostic codes and you're fine.
Do codes work on POCO and Redmi Note series?
Yes! POCO phones are rebranded Xiaomi phones and run MIUI (or POCO's version of it). Same with Redmi. Most codes work across the entire Xiaomi ecosystem Mi, Redmi, POCO, Black Shark. Only exception: some codes are processor-specific (MTK engineering mode only works on MediaTek chips, not Snapdragon).
Why doesn't CIT menu work on my new phone?
Xiaomi removed CIT access on some newer models with MIUI 14. Try *#*#6484#*#* instead. If that doesn't work either, your MIUI version has diagnostic codes disabled. Only option then is enabling Developer Options and using ADB commands from a computer (more complex).
Can secret codes unlock bootloader or bypass Mi Account?
No. Codes can't unlock bootloader (you need official Mi Unlock Tool for that). They can't bypass Mi Account lock or FRP either. After factory reset, you MUST have the previous Mi/Google account login. For actual FRP bypass, check professional FRP tools that work legally.
Is it safe to run all CIT tests repeatedly?
Absolutely. These tests run internally all the time anyway. I've run CIT diagnostics thousands of times on the same phones without issues. It won't wear out your hardware. Just don't leave tests running forever it's pointless and drains battery.
Can I update MIUI using secret codes?
No. Secret codes show your current MIUI version but can't update it. For updates: Settings → About Phone → System Update for OTA. Or manually flash using Mi Flash Tool with firmware from MobiFirms. Always check *#*#1234#*#* for your exact current version before downloading firmware.
📝 Wrapping Up
Secret codes give you insider access to your Xiaomi, Redmi, or POCO phone. The CIT menu alone is worth knowing it's like having a professional diagnostic lab in your pocket. Whether you're buying a used phone, troubleshooting problems yourself, or just curious about what your device can actually do, these codes are incredibly useful.
Quick reminder: information and diagnostic codes are your friends. Factory reset code is the nuclear option (backup first!). Engineering mode is expert territory (look, don't touch unless you know what you're doing).
For serious problems like corrupted firmware, bootloop errors, or IMEI issues, head to MobiFirms.com for tested stock firmware files, professional flash tools, and detailed repair guides. Sometimes the right firmware file and correct flashing procedure beats any secret code.
Save this guide somewhere you can find it later. You never know when you'll need to check IMEI, run a quick diagnostic, or verify what's actually wrong with a phone. If this helped, check out the MobiFirms blog for more Android repair tips, MIUI tricks, and smartphone troubleshooting guides.
Keep exploring, stay informed, and get the most out of your Xiaomi phone! 📱