Why with Face ID on won’t Siri work when the phone is locked? I have to turn Face ID off for Siri to work.

Hello Marymdh49,

If you'd like to be able to access Siri while the device is locked you'll need to enable it. Go to Settings  > Face ID & Passcode, then under the "Allow Access When Locked" section, turn on the toggle switch for Siri.

Control access to information on the iPhone Lock Screen

Cheers!

Marymdh49,

To clarify, are you using supported headphones or CarPlay when asking Siri to read your new messages? If not, please be mindful of the following details:

Siri can announce calls and notifications from apps like Messages on supported headphones and when using CarPlay. You can answer or reply using your voice without needing to say “Hey Siri.”

Announce Calls and Announce Notifications also work with supported third-party apps.

More details found here: Announce calls, messages, and more with Siri on iPhone

If you need further assistance, we suggest reaching out to Apple directly. Depending on your region, you may be able to connect with them here: Get Support

Take care!