Follow these steps. After each step, see if you still need help.
Check for updates
Make sure that your iPhone X is updated to the latest version of iOS.
Check your Face ID settings
To check your Face ID settings, go to Settings > Face ID & Passcode. Make sure that Face ID is set up and that the features you’re trying to use Face ID with are turned on.
Check that nothing is covering the TrueDepth camera
Make sure that the TrueDepth camera on your iPhone X isn't covered with a phone case or a screen protector. Also, check to see if there’s residue or dirt covering the TrueDepth camera.
Make sure that nothing is covering your face
Make sure that your eyes, nose, and mouth are fully visible to the TrueDepth camera.
Face ID works with many sunglasses. If you're wearing sunglasses designed to block certain types of light, then your sunglasses might be blocking the infrared light used by the TrueDepth camera. Try using Face ID without your sunglasses.
Make sure that you're facing the TrueDepth camera
Face ID only works when your iPhone X is in portrait orientation and you’re facing the TrueDepth camera. The TrueDepth camera has a similar range of view as when you take a selfie or make a FaceTime call. Whether your iPhone is lying on a surface or you're holding it in a natural position, make sure that your iPhone X is an arm’s length or closer (10-20 inches) from your face.
If you’re outside in bright sunlight, try repositioning your iPhone X so the sun isn’t directly behind you.
Reset Face ID
If you still need help, reset Face ID, then set it up again. Go to Settings > Face ID & Passcode and tap Reset Face ID. Then tap Set up Face ID to set it up again.
If you can’t enroll your face, take your device to an Apple Retail Store or Apple Authorized Service Provider, or contact Apple Support.
If you need to enter your passcode
You might need to enter your passcode or Apple ID instead of using Face ID in these situations:
- The device has just been turned on or restarted.
- The device hasn’t been unlocked for more than 48 hours.
- The passcode hasn’t been used to unlock the device in the last six and a half days and Face ID hasn't unlocked the device in the last 4 hours.
- The device has received a remote lock command.
- After five unsuccessful attempts to match a face.
- After initiating power off/Emergency SOS by pressing and holding either volume button and the side button simultaneously for 2 seconds.
- If the device's battery is below 10%.