A fingerprint sensor not working can mean the phone ignores your touch, says "Fingerprint not recognised" again and again, or shows that the sensor is unavailable. Phones use three types: a button on the back or side, a sensor under the screen, or one built into the power key. The checks are similar for all three.
In everyday use the reasons are plain: damp or oily fingers, a smudged scanner, a thick screen guard, or prints saved a long time ago that no longer match well. Software updates and cuts on the finger can also change results. This guide goes from the quick fixes to the causes that need a technician. If the phone does not respond to touch anywhere on the screen, read phone touch screen not working. For the group of phone faults see phone not working.
Common causes
1Wet, oily or dirty fingers
How to tellWorks fine after you dry your hand, fails after washing or in summer sweat
What fixes itWipe the finger and the sensor dry, then try again
2Dirty scanner surface
How to tellNeeds many tries; the sensor looks smudged
What fixes itClean it with a soft dry cloth, lightly dampened only if needed
3Screen guard or case blocking an under-screen sensor
How to tellBegan right after fitting a new guard
What fixes itUse a guard made for in-display sensors, or remove it to test
4Saved prints are old or poor quality
How to tellUsed to work, now fails for the same finger
What fixes itDelete the prints and add them again, several angles each
5Software glitch or update
How to tellStarted after an update or a restart is needed
What fixes itRestart, then install the latest system update
6Cut, dry skin or worn finger
How to tellOnly one finger fails, or hands are dry or cracked
What fixes itAdd another finger, and use a moisturiser to restore skin
7Damaged sensor or cable
How to tellSensor not found in settings, or the problem began after a drop or water
What fixes itHand it to a repair centre
How to fix it, step by step
Wash and dry your finger
Clean, completely dry skin is read best. Dry the finger on a clean cloth and press flat and firm, covering the sensor, rather than tapping with the tip.
Wipe the sensor and the area around it
Use a soft, dry microfibre cloth. On a phone with the sensor under the screen, wipe the lower part of the display. Fingerprints, dust and cream can sit on the glass and confuse the reading.
Remove the screen guard or case to test
A thick tempered glass or a case edge can block a button sensor. Under-screen sensors are even more sensitive to guards. If the sensor works without the guard, buy one marked as suitable for fingerprint unlock.
Restart the phone
Switching the phone off and on reloads the sensor service. After it starts, you must enter the PIN or pattern once before the fingerprint works again, which is a normal safety step.
Delete and add your fingerprints again
Open Settings, then Security or Biometrics, then Fingerprint. Enter your PIN, remove the saved prints and add them again. Press the same finger several times at slightly different angles so the phone sees the whole pad.
Add the same finger more than once
Many people register a thumb twice, one wet and one dry version, or add a second angle. More samples improve matching, especially for people who use their hands for work.
Update the system software
Check Settings for a system update. Some updates correct sensor speed and accuracy. Keep the phone charging while it installs.
Check the unlock method settings
Make sure fingerprint unlock is switched on for the lock screen and for apps that ask for it. After several failed tries the phone locks the sensor for a short time, and the PIN opens it again.
How the fingerprint sensor reads your finger
The three common kinds are capacitive (the small button), optical (a light under the screen) and ultrasonic (sound waves under the screen on some models). All of them compare the ridges of your finger to a saved pattern. Wet skin fills the gaps between ridges and spoils the picture, so the problem is usually moisture rather than a broken part.
You come in from the rain and the phone keeps showing Fingerprint not recognised. Dry your finger and the screen, press flat for a second and try again. Use the PIN meanwhile.
Sensor types and what upsets them
| Type | Where | Usual trouble |
|---|---|---|
| Rear or side button | Back panel or power key | Dirt, case cut-out in the wrong place |
| Optical in-display | Lower screen | Wrong screen guard, bright sun, dry skin |
| Ultrasonic in-display | Lower screen | Thick cover or film |
If your sensor is the power button type and the key itself is stiff, read power button not working as well.
When a fingerprint sensor not working needs a technician
If the fingerprint option has vanished from settings, the phone says the sensor failed, or none of your fingers register even after a reset, the hardware is likely damaged. This often follows a drop, water, or a screen swap with a part that does not match the phone.
You can still use the phone with a PIN or pattern. Do not try to bypass the lock, and do not open the phone. Repair costs more when the sensor is part of the screen or the main board.
Biometric machines at work or school
The same advice helps with attendance machines: clean the glass, dry the finger, press with the same part of the finger each time, and re-enrol the person if they have changed. If the machine itself shows an error code or will not power on, use the manual and call the supplier, since codes differ by maker.
Frequently asked questions
Why is my fingerprint sensor not working suddenly, and why is biometric not working?
Wet or dirty fingers, a new screen guard or a software glitch are the usual reasons. Dry your hand, clean the sensor and restart.
What to do if the fingerprint sensor is not working on Android?
Clean the sensor, remove the guard to test, delete and re-add the prints, and update the system. If it still fails, get it checked.
How do I check if the fingerprint sensor is working or not?
Start adding a new print under Settings and Fingerprint. If the screen reacts to every touch, the sensor is alive. No reaction at all suggests damage.
Why does my fingerprint lock not work with wet hands?
Water fills the gaps between ridges and hides the pattern. Dry the finger well, or use the PIN.
Can the fingerprint sensor not working be repaired?
Yes, a technician can replace the sensor or the part it belongs to. Cost depends on whether it is a separate part or built into the screen.