Q. The fingerprint sensor on my iPhone used to be very consistent, but it has been acting weird lately and only works some of the time — which means I have to type in my passcode instead. What might be causing this unreliability?
A. Touch ID is the fingerprint-reading system Apple includes on some of its iPhone and iPad hardware to securely unlock the screen or acknowledge mobile payments. While usually reliable, it can be stymied by factors like dry winter skin or a cut that alters your fingerprint a bit. Lotion, sweat, moisture, oils or other liquids on your hands can also disrupt fingerprint recognition on the iPhone and other smartphones, too.
Trying to unlock the iPhone while cooking — or just after working out in the pool or gym — may also cause Touch ID to fail because your fingertips may scan differently than how the sensor recorded them when you set up your phone. Before using Touch ID, make sure your finger is clean and dry.
You may also want to wipe down the Touch ID sensor with a microfiber cloth or other nonabrasive fabric to make sure residual oil or dirt is not interfering. When you put your finger on the sensor, make sure you are pressing both the Home button and the ring around it for full contact. Restarting the iPhone may help, especially if the Touch ID feature began to behave erratically after an iOS software update.
If you are still having fingerprint recognition issues, open the Settings app on the iPhone’s home screen, select “Touch ID & Passcode,” and on the list choose the fingerprint you first set up. Tap the “Delete Fingerprint” option to remove it. On the main Touch ID & Passcode screen, tap “Add a Fingerprint” to go through the setup steps again so the phone has a fresh copy of your fingerprint on file.
If you are still having fingerprint-recognition issues, contact your nearest Apple Store or authorized service provider for a hardware checkup.
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