Fingerprint and Face ID test

When to test fingerprint and Face ID

Test them when you look at a used device and right after a screen replacement or front camera repair, which is when an in-display fingerprint reader or Face ID is most likely to stop working. The surest check is to add a new fingerprint or face in Settings, then scan with this test.

Common faults and their causes

• iPhone says "Face ID is not available": the TrueDepth camera was damaged, or its cable broke during a screen replacement. Face ID is paired to the logic board, so swapping in another unit usually doesn't bring it back.
• The in-display fingerprint reader doesn't respond: the wrong kind of replacement screen (many cheap screens don't support it), or a screen protector that's too thick.
• Touch ID or a power-button fingerprint reader fails: the button was replaced with the wrong part, or the sensor is scratched or damp.
• You can't add a new fingerprint or face at all: almost certainly a hardware fault.

Websites can't read your biometric data. The test only asks the operating system to confirm it's you, the same way a passkey sign-in works.

What to do if you find a fault

• Remove the screen protector, dry your finger and the sensor, and try again.
• Lost fingerprint or Face ID right after a screen replacement: tell the shop before you pay. See checking a device after a repair.
• Buying a used iPhone: read how to check a used iPhone.