The fingerprint sensor has become an indispensable tool for millions of Android users. Thanks to its convenience and security, it allows us to unlock our devices in fractions of a second and protect our personal information. However, there's nothing more frustrating than suddenly finding that the reader doesn't detect our fingerprint, takes a long time, or simply stops working.
Fingerprint recognition technology has evolved significantly in recent years, but it remains susceptible to physical and software issues. This article breaks down all possible causes and solutions For when your Android's fingerprint sensor stops working, from the simplest, most common issues to more advanced technical problems. If you've already tried the "typical" stuff without success, here's a much more complete and thorough guide that will help you exhaust all options before going to the service center.
Why does the fingerprint sensor stop working on Android?
Fingerprint sensor failure can be due to multiple causes, and it's not always easy to identify the source immediately. The most common causes include:
- Dirt, grease or moisture both on the sensor surface and on the fingers.
- Incompatible screen protector or case (on models with a sensor under the display or on the side).
- Software errors or after failed updates.
- Problems with fingerprint registration (incorrect position, insufficient pressure or deterioration of the print due to wounds).
- Physical damage to the sensor caused by drops, bumps or wear.
- Extreme temperature changes that affect the skin and the sensitivity of the sensor.
- Conflict with third-party applications or misconfigured permissions.
Detecting this root cause is key to applying the most appropriate solution. Below, we'll go over in-depth how to determine the real cause in your case and what to do in each scenario.
Physical solutions: cleaning and checking the sensor
Most reading problems have their origin in external factors. Before going crazy with adjustments or thinking about expensive repairs, Try these basic but effective steps:
1. Thorough cleaning of the sensor and fingers
Dirt is the sensor's main enemy. Dust, grease, sweat, or cream residue can form a film on the reader and make fingerprint detection difficult. Likewise, wet, sweaty, or dirty fingers make reading difficult.
- Wash and dry your hands before attempting to unlock.
- Pass a microfiber cloth (or a specific wet wipe) across the sensor with gentle movements. If the sensor is small, use a cotton swab slightly moistened with water or isopropyl alcohol, without soaking to prevent leaks.
- If the phone itself warns you that the sensor is dirty, Clean the area until no visible residue remains.
This step is much more relevant for rear or side sensors, but also for screen sensors, since the glass itself can accumulate dirt.
2. Check for physical damage or strange movements
Bumps, drops, and scrapes can damage the sensor or the display where it's embedded. Check for cracks, scratches, or a clicking or wobbling sensation. These symptoms may indicate internal damage.
- Do not attempt to disassemble the sensor yourself. if you are inexperienced, as you could aggravate the breakdown.
- If you notice obvious damage, it's best to take the device to a specialized technical service.
3. Remove the case and screen protector
Some protectors or cases aren't compatible with under-screen readers or side sensors. If the problem occurs after applying a new case/protector, remove them and try again without them.
- Protector too thick or scratched: limits or blocks fingerprint reading.
- Edges of the cover: They can cover part of the sensor or interfere with the pressure you need to apply.
If the sensor works again after removing them, look for accessories certified by your phone's manufacturer or use those recommended for fingerprint readers.
4. Take care of your skin's hydration
Excessive dryness or moisture in your hands can make reading difficult. If you tend to have very dry hands, moisturize them lightly (You can rub your finger on your forehead or nose to take advantage of the natural oils, or use moisturizer, but not too much.)
5. Take into account the ambient temperature
Extreme cold dries out the skin and can create microcracks; excessive heat increases sweating, which can create a film that makes it difficult for light to reflect off optical sensors.
- Do not use the reader immediately after going outside if there is a significant temperature difference.
- Allow your finger to return to its natural temperature by gently rubbing it.
- If the mobile is hot, turn it off for a minute and take off the cover to speed up cooling.
- Some models have a improved fingerprint reader mode for cold climates; activate it if available.
If the sensor still doesn't work after these steps, the problem is likely software-related. Read on for all the possible solutions in this area!
Software solutions: resets, updates, and fingerprint management
Not everything is due to dirt or physical wear and tear. Errors often occur after a system change, an incomplete update, the installation of new apps, or a failure in the fingerprint recognition process itself. Here's a rundown of all the software solutions recommended by experts and manufacturers:
1. Restart your phone (and let it rest for a few seconds)
It seems like a typical recommendation, but rebooting solves a lot of problems. Turn off your phone using the power button, leave it off for 20-30 seconds, and then turn it back on. This resets all internal processes, clears the cache, and sometimes makes the sensor work again.
2. Delete and re-register the fingerprint
Errors in fingerprint registration (insufficient pressure, incorrectly placed finger, or recent injuries) can cause the sensor to not correctly recognize your fingerprint.
- Go to Settings > Security > Fingerprint or Unlock with footprint (depending on your model).
- Delete the registered fingerprint(s) and rescan the fingerprint from scratch.
- Make sure you place your finger correctly, in various positions and applying pressure that is neither too light nor excessive.
- Register multiple fingers if possible (thumb, index finger, etc.) and test with all of them.
This solution is especially useful if you've changed your protector or if you have wounds on your fingers.
3. Check that you are using the correct finger
Yes, it may seem absurd, but many mistakes arise from trying to unlock with the wrong finger or at different angles. Check which fingers you have registered and try the correct one.
4. Update the operating system and applications
Updates often include patches to improve sensor accuracy. and fix security bugs. Go to Settings > System > Updates and download any pending versions. Also, update any security apps or banking apps that use your fingerprint, as they may be interfering.
If the error occurred after updating the system or installing a new app, you should consider the next step.
5. Start your phone in safe mode
Safe mode disables third-party apps and lets you know if any apps are causing conflicts.
- Press and hold the power button until the menu appears.
- Press and hold the “Restart” option until the message to restart in safe mode appears.
- Test the sensor in this mode. If it works, the problem is with a recently installed app (uninstall them one by one and test until you find the culprit).
- To exit safe mode, restart your phone normally.
6. Recalibrate the sensor after changing the screen or protector
If you have repaired the screen, changed the display or installed a new sensor, sometimes it is necessary to calibrate the sensor to adapt it to the new thickness or surface type. Check your model's settings to see if this is possible, or contact an authorized service center to ensure the calibration is correct.
7. Reset factory settings as a last resort
When all else fails, a factory reset can fix deep software errors, corrupted files, or malware. Always make a backup before, since you will lose all your data.
- Go to Settings > System > Reset options / Backup & reset > Reset all data.
- Confirm the action and wait for the process to finish.
After starting the device, register your fingerprint again and check if the sensor responds correctly.
Specific problems in recent models: under-screen readers and side sensors
The sensors under the screen and the side readers have some peculiarities that should be taken into account.
Under-screen sensors
- The thickness and quality of the screen protector have a lot of influence. Always use manufacturer-certified protectors (like “Made for Google” on Pixel) and register your fingerprint after installing it.
- Sweat or moisture under the glass affects the reflection of the optical sensor.
- Direct sunlight can make reading difficult. Protect the sensor from excessive light and keep your finger firmly planted.
- Some phones allow you to increase the intensity of the sensor area to improve accuracy in cold weather.
Side sensors (on power button)
- The case may cover or hinder access to the sensor. Remove the cover and register the fingerprint again.
- Clean the button with a mild disinfectant wipe.
- On Pixel Fold phones, review the “Tap to unlock anytime” settings to prevent accidental unlocks.
Advanced Tips and Important Considerations
If you've followed all the steps above and the sensor still isn't working, there are a few other things you should consider:
- Internal damage After a fall or impact, they may require professional repair. Don't attempt to disassemble your phone if you're not a specialist; you could make the problem worse.
- Warranties usually cover failures not caused by misuse or drops. If your device is within the warranty period and the sensor fails for no apparent reason, consult an authorized service center.
- If you changed the screen, requires that it be compatible with the fingerprint sensor and have it installed by accredited personnel.
- Recalibrate the footprint after any major repair or component replacement.
Frequently asked questions about fingerprint sensor failures
Why does the fingerprint sensor work sometimes and not other times?
It may be due to microdamage, intermittent soiling, or variations in pressure or finger placement. Skin varies depending on humidity, temperature, or even minor injuries. It records the same finger in multiple positions and keeps the sensor clean.
Which screen protectors are best for under-display sensors?
The official protectors or those certified by the manufacturer (“Made for Google,” “Samsung Approved,” etc.) are the only guarantee. Avoid generic or overly thick ones.
Can I maintain security if the fingerprint sensor doesn't work?
Yes, you can resort to alternative methods such as PIN, pattern, facial recognition or password until the problem is resolved. Some phones allow you to combine several unlocking systems.
When to go to technical service
If the problem persists after wiping, resetting, updating, and re-registering your fingerprint, it all points to a hardware failure. In these cases, it is advisable to take the mobile to a Official technical service:
- The technician will check for damage, sensor malfunction, or the need for replacement parts.
- If the damage was not due to a fall or misuse, the warranty may cover the repair.
- Always request that the replacement screen be compatible with the fingerprint sensor, and that proper calibration be performed after the repair.
Don't risk opening your phone yourself: the sensors are delicate parts, and any mistake can render your phone unusable.
How to avoid future problems with the fingerprint sensor
The best way to ensure proper functioning of the fingerprint sensor on Android is prevention:
- Clean the sensor and screen regularly with non-abrasive products.
- Re-register your fingerprints when you change the protector, screen, or case.
- Always use certified accessories or recommended by the manufacturer.
- Update your system and security apps when new versions are available.
- Keep the skin on your fingers in good condition, avoiding extreme dryness or wounds in the recording area.
Applying these recommendations and maintaining proper hygiene and calibration will promote optimal performance, avoiding complications and improving unlocking speed.
