The Sensor Failure
The Apple Watch utilizes a sensor array on the back of the device to detect human skin. This “Wrist Detection” feature is how the watch knows you are wearing it. If you take the watch off and set it on a desk, the sensors realize it has been removed and instantly lock the screen with a passcode to protect your Apple Pay data. However, if you have dark tattoos on your wrist, or if you attempt to wear the watch over a long-sleeved shirt or a wetsuit during winter sports, the sensors will fail. The watch will constantly assume it has fallen off your body and will aggressively lock itself every 30 seconds, forcing you to type your PIN code constantly. To use the watch over clothing, you must disable the sensor.
How to Turn Off Wrist Detection
You can force the watch to ignore the skin sensors via the security settings.
- Open the Settings app directly on your Apple Watch (the grey gear icon).
- Scroll down the main list and tap on Passcode.
- Scroll all the way down to the bottom of the page.
- Look for the master toggle switch labeled Wrist Detection.
- Toggle this switch to the Off position (the green background will disappear).
A Dumb Watch
The change takes effect immediately. The Apple Watch will completely stop polling the rear sensors. You can now strap the watch over a thick snowboarding jacket, and it will remain unlocked and fully functional. Important Note: Disabling this sensor has severe security consequences. Because the watch no longer knows when it has been removed from your body, it will automatically delete your credit cards from Apple Pay to prevent theft.