Xiaomi Redmi 4 is one of the most popular budget smartphones with support for fingerprint scanner. Despite the age of the model (released in 2016), its sensor remains a reliable tool for protection. However, many users face difficulties in setting up, from errors in adding a fingerprint to sudden failures in operation. In this article, we will analyze all the nuances from the basic installation to advanced tricks to improve recognition accuracy.
It's important to understand that the Redmi 4 scanner, codenamed prada, is based on a capacitive sensor that reads the pattern of papillary lines. Unlike the ultrasonic or optical scanners on flagships, it requires the right finger position and the cleanness of the sensor. If you haven't used biometrics on Android before, the instruction will help you avoid typical errors, such as registering only part of the fingerprint or miscalibrating.
Preparing the smartphone before setting up the fingerprint
Before adding a fingerprint, make sure your Xiaomi Redmi 4 is ready for the procedure.Neglect of preparation is the main reason why the scanner later is unstable or refuses to save data.
First, check out the MIUI version. The fingerprint scanner is fully supported starting with MIUI 8, but MIUI 10+ is recommended for stable operation. To find out the version, go to Settings → About Phone → MIUI Version. If you have outdated firmware, update it through Settings → System Update. Redmi 4 does not officially receive new versions of Android, but security patches and patches for the scanner come out regularly.
Second, clean the fingerprint sensor (located on the back of the camera) and your finger of fat, dust or moisture. Use a dry microfib wipe - alcohol or wet wipes can damage the sensor's protective coating. Also make sure that there are no cuts or calluses on your finger: they distort the print pattern.
- 📱 Update. MIUI Up to the latest version available for your model.
- 🧴 Clean the sensor and finger from contaminants (without aggressive means!).
- 🔋 The battery charge should be at least 30% – at low charge, the system can interrupt the process.
- 🔒 Set a pattern lock or PIN — This is a prerequisite for the scanner.
⚠️ Warning: If you reset your phone to factory settings, all the fingerprints you saved will be deleted.
Step-by-step: how to add a fingerprint
The process of adding a fingerprint to Redmi 4 takes no more than 2-3 minutes, but requires accuracy. Follow the instructions carefully to avoid errors such as "failed to save a fingerprint" or "too little data."
Open Settings → Screen lock and fingerprint. If you have a PIN or a pattern lock installed, the system will ask you to enter it for confirmation. Then click "Add fingerprint" and follow the prompts on the screen.
- Place your finger on the sensor and wait for a vibration or a beep.
- Raise your finger and put it back, slightly shifting to the side (the system will tell you the direction with the arrow).
- Repeat the action until the progress scale is 100% complete.
- Name the print (for example, "Indicative right") and save.
The key is, don't press your finger too hard. The optimal pressure is a light touch, like when you press a touch screen, and if you press it, the fingerprint pattern gets distorted, and the scanner only works when the finger is perfectly positioned.
Finger dry and clean | Sensor undamaged or uncontaminated |PIN or pattern lock installed |Battery charge sufficient-->
⚠️ Warning: If you add a fingerprint, you get a "Dirty Sensor" error, wipe it with an alcohol wipe (no more than 70% alcohol!) and try again in 1-2 minutes!
Optimization of the scanner: expert advice
Even after a successful setup, the scanner on Redmi 4 may not work perfectly: it can slowly recognize a fingerprint, require several attempts, or fire after a time, most often due to incorrect registration or software restrictions.
Use these tips to improve accuracy:
- 🔄 Add the same finger 2-3 times at different angles, for example, register "Indicative right", then "Indicative right (side)", with your finger at a different angle, which will increase the chances of recognition.
- ⚡ Turn off animation in MIUI. Go to Settings. → Additionally. → For developers and install "Window animation", "Transition animation" and "Duration of animator" on 0.5x. This will speed up the scanner's response.
- 📵 Redmi 4 scanner supports up to 5 fingerprints, but the more they are, the slower the recognition works.
- 🔋 Restart your phone after adding a new fingerprint. Sometimes the system needs to restart for the sensor to work properly.
If the scanner stopped working after the MIUI update, try resetting it. To do this, delete all the saved prints, restart the phone and add them again, 80% of the time this solves the problem.
💡
To speed up unlocking, put your finger on the sensor before the screen lights up (when lifting the phone). The scanner on Redmi 4 supports recognition in sleep mode!
Solving common problems with the scanner
Even with the right setup, Xiaomi Redmi 4 users are faced with common errors.
| Problem. | Possible cause | Decision |
|---|---|---|
| The scanner doesn't respond to the touch. | Sensor contamination or plume damage | Clean the sensor; if it doesn’t help, take your phone apart and check the plume |
| Error "failed to save the print" | Too quick finger removal or weak contact | Keep your finger on the sensor until vibration; repeat the registration |
| The scanner works once. | Inadequate learning capacity of the system | Add one finger 2-3 times at different angles |
| After the update, the scanner stopped working. | Reset sensor settings in a new firmware | Remove all prints and add them again. |
If none of these things worked, check firmware integrity. Sometimes the scanner errors are related to "curve" custom ROMs or unofficial patches. Return to stock MIUI via Fastboot or Recovery.
What to do if the scanner is not working at all?
Security: How to protect data when using a fingerprint
The fingerprint scanner on Redmi 4 is convenient, but it's not 100% secure. PIN-If you have a code or a password, biometrics can't be changed if they're compromised, so it's important to take precautions.
First of all, don't use print as your only method of unlocking. Always set a backup PIN or a pattern lock. In MIUI, it's a must, but some custom firmware allows you to disable the backup method - don't do it!
Second, remember that you can reconstruct your fingerprint from a high-resolution photograph (like a print on a glass) to minimize the risks of:
- 🔐 Do not use the scanner to log in to banking applications (it is better to enter). PIN password).
- 📱 Turn off fingerprint unlock in safe mode (setting in Settings) → Screen lock → Additionally).
- 🚫 Do not register fingerprints that you often leave on public surfaces (such as your thumb).
Also, you should know that on Redmi 4, fingerprints are stored in the Trusted Execution Environment (TEE) and not transferred to the cloud, but when you reset your phone to factory settings, all biometric data is deleted without recovery.
💡
A fingerprint is convenient, but it's not 100% safe. Always pair it with a fingerprint. PIN-code and do not apply for critical operations (payments, access to passwords).
Additional Features of the Fingerprint Scanner on Redmi 4
In addition to unlocking the screen, the fingerprint sensor on Xiaomi Redmi 4 supports several hidden features that many are unaware of.
One of the most useful is the quick opening of applications, for example, you can set the camera to launch with double-pressing on the sensor (even when the screen is off).
- Go to Settings → Additional → buttons and gestures.
- Select "Prince Sensor."
- Activate the option "Double touch to start the camera".
Another hidden possibility is to hide notifications on a locked screen, so if you add a fingerprint as an unlock method, you can only set up the display of sensitive notifications after scanning.
- Open Settings → Notifications and Status bar.
- Select "On the lock screen."
- Set the “Hide Notification Content” switch to the “Locked screen only” position.
You can also use the scanner to log in to some apps (e.g. Mi Home or Google Play), so in the app settings, look for the Security section and activate the Unlock Fingerprint option.
What to do if the scanner stops working after the update
One of the most common problems with Redmi 4 is the scanner failure after the MIUI update, which is because newer firmware versions sometimes reset the sensor settings or conflict with its drivers.
The first thing you need to do is remove all the fingerprints you've saved and add them back.
- Go to Settings → Screen lock and fingerprint.
- Enter. PIN-proof-code.
- Click on the saved print and select "Delete".
- Reboot your phone and add the print again.
If this doesn’t help, try cleaning the system cache:
- Turn off the phone.
- Press the Power + Volume buttons up to enter Recovery.
- Choose Wipe & Reset → Wipe Cache.
- Reset the device.
In extreme cases, you may need to roll back on the previous version of MIUI. To do this, download the necessary firmware from the official Xiaomi website (link) and thread it through Fastboot or Recovery.
💡
If the scanner stopped working after the update, 90 percent of the time, removing and re-addition of fingerprints helps, and only in rare cases, a firmware rollback is required.