For the Apple iPhone 15 Plus, sensor obstruction, enrolled appearance/finger, protector, environment and hardware should be separated. First, enter the passcode once and retry. Enter the passcode once. If biometrics then work normally, nothing was ever wrong. Clean the sensor or the camera area and your finger, and retest.
Differential
Likely causes of “Apple iPhone 15 Plus biometric unlock is not working”, and how to tell them apart
- 1
The phone has restarted and requires the passcode first
What separates it It refuses biometrics after a restart, an update or a long idle period, and works again once the passcode is entered. This is a deliberate security requirement.
How to confirm Enter the passcode once. If biometrics then work normally, nothing was ever wrong.
- 2
The sensor or camera is dirty or covered
What separates it Recognition has become unreliable rather than failing outright. A fingerprint reader with grease on it, or a front camera behind a smudged protector, has less to work with.
How to confirm Clean the sensor or the camera area and your finger, and retest.
- 3
The face is being presented differently from enrolment
What separates it It fails at unusual angles, in the dark, in bright backlight, or when lying down. Face recognition depends on the sensor seeing what it expects.
How to confirm Try at a normal distance and angle in even light. Where appearance has changed, adding an alternative appearance is the documented fix.
- 4
Something is covering the sensor array
What separates it Face unlock fails entirely with the phone in a case or with a cover over the top of the screen. The sensors are in a specific place and a case lip or a protector can block them.
How to confirm Remove the case and any protector over the sensor area and retest.
- 5
Too many failed attempts have disabled it
What separates it It refuses biometrics entirely and demands the passcode. Repeated failures disable biometric unlock deliberately.
How to confirm Enter the passcode; biometrics re-enable afterwards. This is protection working, not a fault.
- 6
The enrolment itself is poor
What separates it It has always been unreliable rather than having degraded. A fingerprint enrolled with one part of the finger, or a face enrolled in odd conditions, gives the sensor a narrow reference.
How to confirm Delete the enrolment and redo it carefully, presenting the finger at varied angles or the face in even light.
- 7
A repair replaced a component tied to the biometric hardware
What separates it It stopped working after a screen or sensor repair. Biometric components are cryptographically paired to the device on both platforms.
How to confirm This is not a configuration matter — an unpaired replacement part disables the feature by design.
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether it fails always or intermittently, which separates a hardware or pairing problem from an enrolment or conditions problem.
- Whether it started after a restart, an update, a repair, or a new case or screen protector.
- Whether the passcode works normally, which confirms the phone itself is fine.
- The conditions when it fails: wet hands, cold, darkness, backlight, lying down, wearing something on the face.
- Whether a screen protector or case is fitted and whether it covers the sensor area.
- How the enrolment was originally done, and whether more than one finger or appearance is enrolled.
Try in this order
0 of 7 completedEnter the passcode once and retry
ReversibleBiometrics are deliberately disabled after a restart, an update, a long idle period or several failures, and require the passcode to re-enable. A great many 'it stopped working' reports are this behaving exactly as specified.
Clean the sensor, the camera area and your finger
ReversibleRecognition that has become unreliable rather than failing outright is usually contamination. A fingerprint reader with grease on it, or a front sensor behind a smudged protector, simply has less to work with.
Remove the case and any screen protector over the sensor
ReversibleAn in-display reader looks through the screen, and a face sensor array sits in a specific place that a case lip or a cover can block. Testing without them separates an accessory problem from a hardware one in seconds.
Retest in the conditions it was enrolled in
ReversibleA normal distance and angle in even light, with dry hands. Failing in the dark, in backlight, lying down, or with wet hands is the sensor being honest about its confidence rather than failing.
Add an alternative appearance
ReversibleWhere appearance has changed — glasses, a beard, a different everyday look — this is the documented fix, rather than deleting and redoing the original enrolment.
Delete and redo a poor enrolment carefully
Reset / data riskA fingerprint enrolled from one part of the finger, or a face enrolled in odd lighting, gives the sensor a narrow reference it will never do well with. Redoing it deliberately, with varied angles or even light, fixes the root rather than the symptom.
Establish whether a repair is involved
ReversibleBiometric components are cryptographically paired to the device on both platforms, and an unpaired replacement part disables the feature by design. That is not a configuration problem and no amount of re-enrolling addresses it.
Model-specific
What is true of this model and not of its siblings
- Model scope
- A2847/A3093/A3094/A3096. Apple iPhone family; connector, modem, camera, biometric and iOS eligibility vary by exact model.
- Connector
- USB-C. A cable that fits is not necessarily a cable rated for this phone's charging speed — USB-C carries several power profiles and a cable built for data will charge slowly or intermittently while seating perfectly.
- Biometric
- Face recognition rather than a fingerprint reader. It depends on the sensor array seeing the face as it was enrolled, so darkness, strong backlight, unusual angles and lying down all reduce confidence — and a case lip or a screen protector over the sensor area disables it outright.
- SIM
- Carries an eSIM. An eSIM does not travel with the handset the way a plastic SIM does: a phone swap, a factory reset or a repair can leave the profile behind, and restoring it is a carrier action rather than a phone setting.
- SIM
- Supports two active lines. The default line for calls, for messages and for cellular data are three separate settings, and getting them crossed produces calls arriving on one number while data or messages use another — with almost no indication that anything is wrong.
- Modem
- 5G capable. In marginal 5G coverage the phone hands repeatedly between 5G and LTE, which costs more battery and generates more heat than settling on either — so the preferred-network setting is a real diagnostic lever rather than a preference.
- Charging
- Supports wireless charging. Coil alignment is tighter than it looks and a thick case, a metal plate or a card in the case defeats it entirely — so wireless charging failing while cable charging works is usually the case rather than the phone.
- Water resistance
- Rated water resistant, which is not waterproof and which degrades with age, drops and seal disturbance. The rating covers incidental exposure; it is not a guarantee, and moisture-detection warnings are deliberately conservative and can persist after the port feels dry.
- Platform
- iOS. Settings paths, permission models and background-execution rules differ substantially from Android, so a procedure written for an Android phone will not map onto this one screen for screen.
- Panel
- An OLED panel, where each pixel emits its own light. Dark mode genuinely reduces consumption because black pixels are switched off, and a static bright element left on screen for very long periods is the one wear risk this panel type has that LCD does not.
- Wireless charging
- Carries a MagSafe magnet array, so the charger aligns itself. That removes the alignment guesswork of plain wireless charging, but a thick case, a metal plate or a card between phone and charger still defeats it — and the supported wattage differs across the product line.
- Size class
- One of the larger models in its line. The bigger battery gives a materially higher rated runtime, and the extra weight matters for adhesive mounts and magnetic car holders, which are frequently rated for lighter phones.
- Sensor resolution
- A high-resolution main sensor. It produces substantially larger files than a 12-megapixel camera, which is a direct and frequently unnoticed reason storage fills faster here than on an older model used identically.
- Symptom boundary
- This record covers Apple iPhone 15 Plus when it biometric unlock is not working. A different symptom on the same hardware, or this symptom on a different Apple product line, has its own record with its own causes and its own cited source.
Stop boundary
When this stops being a self-service repair
- !It stopped after a screen or sensor repair — the replacement part is not paired to the device, which only an authorized repair can resolve.
- !It fails consistently with a clean sensor, no case, no protector and a fresh enrolment, which points at the hardware.
- !It stopped after a drop or liquid exposure.
- !The passcode is also not accepted, which is a different and more serious problem than biometrics.
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Face unlock fails in the dark.+
Try at a normal distance and angle. Recognition depends on the sensor seeing what it expects, and darkness, strong backlight and lying down all present the face differently from how it was enrolled. Where your everyday appearance has changed, adding an alternative appearance is the documented fix.