Face ID makes unlocking and authentication convenient, but a good selfie does not prove facial recognition works. A used iPhone may have a TrueDepth issue, something obscuring its sensors or merely a disabled setting. Because Face ID relates to your biometric information, testing at a shop should also respect privacy.
1. A selfie alone is not the test
Face ID relies on the TrueDepth system and authentication software, not just a front-camera picture. Open Camera to test photos and video, but then inspect Settings > Face ID & Passcode separately. If the phone says Face ID cannot be set up or reports a hardware problem, do not assume it will resolve itself.
Apple suggests checking software, settings and obstructions before deciding service is needed. Misaligned screen protection, a case blocking the sensor area or dirt can interfere; remove a suitable accessory and test again.
2. Test a clean phone without leaving your face behind
At a shop, ask staff to demonstrate that a controlled test configuration can enter Face ID setup and unlock. Do not enroll your own face on a display phone and then walk away. Set up your biometric profile only after handover, removal of the former owner’s account and creation of your own passcode.
After handover, follow Apple’s setup circle in Face ID & Passcode, lock the screen and unlock several times at a normal distance. If recognition struggles, retest without an obstructive case or protector. An iPhone may legitimately request a passcode at certain times, such as after restarting, even when Face ID is healthy.
3. Separate test conditions from a repair issue
If recognition fails only with a mask or an unusual angle, check whether the model and settings support that mode. Review iOS version, sensor area, lighting and distance. Record the exact error for the seller rather than repeatedly resetting the whole phone.
Apple advises trained service when the camera fails and Face ID cannot be set up. Do not replace the sensor assembly yourself or trust unknown repair apps; the system includes laser components with specific safety requirements.
4. Protect privacy during testing
Apple says Face ID data is encrypted, is not saved to iCloud and does not leave the device. Still, on a phone you do not yet own, avoid adding your biometric profile to a shared test setup. After purchase, use an Apple Account and passcode you control and review which functions are allowed to use Face ID.
If you return or exchange the unit, follow the seller’s process for removing your personal data first. Turning off Face ID alone would leave photos, accounts or signed-in apps behind.
5. Check the rest of the phone too
The used iPhone 13 and used iPhone 15 Pro support Face ID according to Apple. At TECHBUY, ask for confirmation on the individual unit and record any issue before paying.
Good Face ID does not prove the battery, speakers, charging port or account state is sound. Test the functions you use daily and read the used-device warranty and return terms.
Conclusion
Check Face ID as its own function on a clean phone while protecting privacy. Sources: Apple Face ID troubleshooting and setup guidance.
