The Galaxy S23+ uses an ultrasonic fingerprint reader under the 6.6 inch display and face recognition through the front camera, and unlock trouble on it usually comes down to the screen protector, the registration or a software change. The ultrasonic reader makes a three-dimensional map of the finger and works with damp skin, but it needs a clear path to the glass, so a protector that was not made for it, one with a gap or one that is cracked over the sensor causes failures. If problems began after you fitted a protector, remove it to test, and if you want one, choose a type designed for the S23+.
The checks in more detail
After any change, delete and register the fingerprint again, since the sensor learns it through whatever is on the glass. Open Settings, Security and privacy, Biometrics, Fingerprints and review the list. Register the same finger two or three times at different angles, and add a second finger. Press flat and cover the sensor, which sits low on the screen; many failures are a thumb landing too high. Check that Unlock phone is on and that app verification works. For face recognition, in the same menu, make sure the lens is clean, register in good light and add an alternative look if you wear glasses. Samsung describes face recognition as less secure than a fingerprint.
Software can also change behavior. After a One UI update, the phone may ask for the PIN and the reader may take a day to settle. Update the phone, restart it and run Samsung Members diagnostics. If a screen repair preceded the problem, an uncalibrated display can stop the reader enrolling; ask Samsung or a repairer with the right tools. A work profile or management policy can disable biometrics, so check with the administrator. If nothing works, a factory reset after a backup rebuilds the settings, though it should be a last resort. Contact Samsung with the serial number if the reader does not respond. Keep the PIN safe, since it is always the fallback.
The S23+ is recent enough to have Samsung's current One UI features, so check for a software setting that changed: Settings, Security and privacy, More security settings, may contain biometrics options added by updates, such as a check for fingerprint when the phone is locked by a work profile. The 6.6 inch screen is a little smaller than the S24+'s, which puts the sensor slightly differently in the hand, so a habit from another phone may not suit it. If you use a case with a screen lip, take it off for the test, because a lip that overlaps the glass can press the protector over the sensor.
Differential
Likely causes of “Samsung Galaxy S23+ biometric unlock is not working”, and how to tell them apart
- 1
A protector not made for the sensor
What separates it Reads fail
How to confirm Use one designed for the S23+ and register again
- 2
A stale registration
What separates it Recognition is poor
How to confirm Delete and register twice
- 3
An uncalibrated replacement display
What separates it The reader will not enrol
How to confirm Samsung service
- 4
A management policy
What separates it Biometrics are grayed out
How to confirm Check with the administrator
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether a protector is fitted
- Whether the screen was repaired
Try in this order
0 of 3 completedDelete the fingerprint
ReversibleAnd register it twice.
Add a second finger
ReversibleAs a backup.
Test with the protector and case off
ReversibleRemove the screen protector and any case, clean the screen and your finger, and try the reader again. If it works, the protector was the cause: fit one made for ultrasonic readers, then delete and register the finger again while holding the phone steady.
Model-specific
What is true of this model and not of its siblings
- Ultrasonic
- It works with damp skin.
- Low placement
- Press where the sensor sits.
Stop boundary
When this stops being a self-service repair
- !If the reader does not respond after these steps, contact Samsung with the serial number
- !Avoid unofficial screen repairs
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why does it ask for the PIN?+
After a restart or update.
Can a protector block it?+
Yes.
Is face unlock as secure?+
Samsung rates it lower.