Touch id on iMac

Predicated on the User Profile iMac 24″, macOS 13.2 and is using the OEM Apple Touch ID enabled Apple Keyboard

1 - Turn off the keyboard and pause and then turn it back ON.

Does it work now ?

2 - If not, cable the keyboard to the computer using the OEM cable that came with the keyboard. Make sure the KB is turned ON

Does it function as expected

If still not working contact Apple as per below

Get Support Choose a product and we’ll find you the best solution.Start now and open an Apple Support Ticket as they are Apple Employees to deal will these types of issues .

bozara wrote:

My touch id quit working on iMac. Tried to reset it and the option disappeared on settings. ???

If Touch ID disappeared from System Settings, try booting into Safe Mode then restart normally. That will sometimes fix anomalies.

How to use safe mode on your Mac - Apple Support

I have had this problem several times on an iMac running Ventura. It seems to happen when the keyboard battery runs out. I tried all sorts of combinations (after re-charging) of connecting via cable / wireless, re-booting and trying to change settings (which greyed out then came back then greyed out again) - all without success. Finally, just switching off the key board using the small on/off switch at the back did the trick.

I had this happen a while back, dragged the imac and keyboard to the apple store, they fiddled with it a bit and it worked. Just started again after having my magic keyboard swapped out because of a failing key (sigh) and have found that these steps will generally work, but sometimes you'll only get an hour or so of functioned Touch ID out of it. Sadly there is no longer a way to factory reset the keyboard via the OS (Thanks, Ventura...) so the most obvious troubleshooting step is no longer available. If it continues, I would bite the bullet and drag it off the Apple Store for help.