Firmware updates with macOS 15.0, 14.7 and 13.7

… For many years now, firmware updates have only been supplied in macOS updates and upgrades, and haven’t been offered as separate installations. It therefore follows that the only Macs that can receive firmware updates are those still supported by one of the three supported versions of macOS. If the most recent version of macOS your Mac can install (without using Open Core Legacy Patcher) is Monterey, that automatically means that it can’t get any further firmware updates, as the final version of Monterey was 12.7.6, released on 29 July 2024. In practice, though, Apple normally stops revising EFI firmware well before that event, and this year has followed that pattern again.

Which firmware should your Mac be using?

How to check your Mac’s firmware version
The simplest way now is to run either of my free tools SilentKnight or LockRattler, available from their product page. Alternatively, use the About This Mac command at the top of the Apple menu; hold the Option key and click on the System Information command. In the Hardware Overview listing, this is given as the Boot ROM Version or System Firmware Version.

What to do if your Mac’s firmware is different from that shown
If the version is higher than that given here, it indicates that Mac has installed a more recent version of macOS, which has installed a later version of the firmware. This is almost invariably the result of installing a beta-release of the next version of macOS. This occurs even when the newer macOS is installed to an external disk.

If the installed version of firmware has a version which is lower than that shown, you can try installing macOS again to see if that updates the firmware correctly. If it still fails to update, you should contact Apple Support.