Face ID unlocks the phone by projecting and reading an infrared dot pattern on your face. When it stops working, the phone either says Face ID is not available, fails to recognize you repeatedly, or does not even attempt to scan — the lock screen goes straight to the passcode prompt without the Face ID animation. The cause ranges from a dirty sensor that takes seconds to fix, to a hardware failure that requires component-level repair.
Quick checks first
Clean the TrueDepth camera
The Face ID sensor array is in the notch or Dynamic Island at the top of the screen. It includes an infrared emitter, a flood illuminator, and an infrared camera. Any obstruction over these components prevents Face ID from working:
Wipe the top of the screen with a clean microfiber cloth. Focus on the notch or Dynamic Island area. Oils, fingerprints, and dust on the sensor window block the infrared light
If you use a screen protector, check that it is not covering or partially covering the sensor area. Some screen protectors — especially those not designed for your specific iPhone model — extend too far and block the Face ID sensors. Tempered glass protectors with a cutout for the notch are safe; full-cover protectors without a cutout can interfere
Check for debris in the notch area. Lint from pockets, dried liquid residue, or small particles can block the sensors without being immediately obvious
Check if Face ID is blocked
Face ID needs to see your entire face. Common situations where it fails:
Face coverings: Standard face masks block Face ID unless you have enrolled a Face ID with Mask appearance (available on iPhone 12 and later running iOS 15.4 or later). To set this up: Settings, Face ID and Passcode, enter your passcode, Face ID with a Mask, toggle on and follow the enrollment steps
Sunglasses: Some polarized sunglasses block the infrared light that Face ID uses. If Face ID consistently fails with a specific pair of sunglasses, those lenses are filtering the IR wavelength. Settings, Accessibility, Face ID and Attention, toggle off Require Attention for Face ID — this makes Face ID less secure (it will not verify your eyes are open and looking at the phone) but works through most sunglasses
Holding angle: Face ID works best at arm's length, 10 to 20 inches from your face, with the phone roughly vertical. Holding the phone flat on a desk while looking down at it, or at an extreme angle, can prevent recognition
Lighting: Very bright direct sunlight hitting the sensor can interfere with the infrared scanner. Shade the phone slightly with your hand or body if Face ID fails outdoors in bright conditions
Software fixes
Reset Face ID and re-enroll
The stored face data can become mismatched with your actual appearance if your appearance has changed significantly (major weight change, new facial hair style, different glasses) or if the data has become corrupted:
Go to Settings, Face ID and Passcode, enter your passcode
Tap Reset Face ID
Tap Set Up Face ID and follow the enrollment — slowly rotate your head in a circle so the camera captures all angles
After the first scan, tap Continue and do the second scan
If Face ID works immediately after re-enrollment but degrades over time, the machine learning model that adapts to your appearance may be struggling with rapid changes. Face ID continuously updates its model of your face to accommodate gradual changes like aging, facial hair growth, and different hairstyles. Significant sudden changes (shaving a beard, switching from glasses to contacts) can cause temporary failures that resolve after a few successful passcode unlocks — each time you enter your passcode after a Face ID failure, the system updates its model.
Add an alternate appearance
If Face ID works sometimes but fails consistently in a specific situation (with glasses on but not off, or vice versa), add an alternate appearance:
Settings, Face ID and Passcode, enter your passcode
Tap Set Up an Alternate Appearance
Enroll while wearing the glasses, hat, or other accessory that causes failures
You can have one primary and one alternate appearance enrolled simultaneously. If you need more variation than two appearances accommodate, use the passcode-entry training method — each passcode unlock after a Face ID failure teaches the system your current look.
Update iOS
Face ID bugs are periodically discovered and patched in iOS updates. If Face ID stopped working after an iOS update, check for a subsequent patch that may fix the regression:
Settings, General, Software Update — install any available update
If no update is available and the problem started with the current version, a future update will likely address it. In the meantime, use the passcode
Check Face ID settings
Verify that Face ID is enabled for the functions where it is not working:
Settings, Face ID and Passcode — check that iPhone Unlock, iTunes and App Store, Wallet and Apple Pay, and Password Autofill are toggled on
If Face ID works for unlocking but not for App Store purchases, the toggle for that specific function may have been turned off
Force restart
A force restart clears temporary system state that can disable Face ID:
Press and quickly release Volume Up, press and quickly release Volume Down, then press and hold the Side button until the Apple logo appears
After restart, test Face ID immediately. If it works after restart but fails again after hours or days of use, a specific app or process may be interfering — monitor which apps are running when Face ID fails
"Face ID is not available" error
When the phone displays the message Face ID is not available or prompts you to set up Face ID even though it was previously configured, the system cannot communicate with the Face ID hardware. This is more serious than a recognition failure:
After a drop: Impact can disconnect the TrueDepth camera flex cable from the logic board. The cable and connector may be intact but loosened from the force. A technician can open the phone and reseat the connection
After water exposure: Even though modern iPhones are water-resistant, submersion beyond the rated depth or duration, or exposure to steam, chlorine, or saltwater can cause corrosion on the Face ID components. Water damage to the TrueDepth camera is not covered under the standard warranty
After a screen replacement: Face ID is paired to the specific TrueDepth camera module that came with the phone. If a screen replacement transferred the original TrueDepth module correctly, Face ID should continue working. If the module was damaged during the repair or replaced with a non-original part, Face ID may be permanently disabled. This is one of the most common reasons Face ID fails after a screen repair — reprogramming the replacement sensor requires Apple's proprietary calibration system
After a software update failure: A failed or interrupted iOS update can corrupt the Face ID configuration. Try resetting Face ID (Settings, Face ID and Passcode, Reset Face ID) and re-enrolling. If the error persists, restore the phone through iTunes or Finder on a computer, which performs a complete software reinstall
Hardware issues
If no software fix resolves Face ID, the hardware components may be damaged:
TrueDepth camera failure: The dot projector, flood illuminator, or infrared camera can fail individually. A failed dot projector prevents face mapping entirely. A failed flood illuminator prevents Face ID from working in low light. A failed infrared camera prevents the system from reading the dot pattern. Each component failure produces the same user-facing result — Face ID unavailable
Flex cable damage: The ribbon cable connecting the TrueDepth assembly to the logic board is thin and fragile. Repeated drops, screen flexing, or improper repair can damage it. A damaged flex cable may cause intermittent Face ID failures before complete failure
Logic board issue: The secure enclave on the logic board stores the enrolled face data and processes Face ID authentication. Damage to this area of the board — from impact, liquid, or electrical fault — can disable Face ID permanently on that specific board
Apple charges a flat rate for Face ID repair (classified as other damage) unless the phone is under AppleCare+. Third-party repair options are limited because the TrueDepth system is serialized to the logic board.
Face ID repair in Marion
Marion Phone Repair diagnoses Face ID failures — determining whether the issue is software settings, a dirty sensor, a loose connection, or a hardware component failure, and performing the appropriate repair.