How to Restore Your Mac's Firmware

Reset Your Mac's Firmware to a Known Good State

System Information showing the Mac Model Identifier
The Model Identifier will be your Mac's model name with two numbers separated by a comma. Screen shot courtesy of Coyote Moon, Inc.

Mac firmware restoration is the process of resetting your Mac's internal firmware to a known good state. This is a basic method for fixing a firmware update that has problems, becomes corrupt, or, for any number of reasons, fails to complete.

Apple supplies firmware updates from time to time, and although very few people have any trouble after installing them, problems do crop up now and then. The most common problems are the result of a power failure during the installation process, or turning your Mac off during the installation because you think it's stuck.

Many Intel Macs, that include a built-in CD/DVD drive, have the ability to restore corrupt firmware to a known good state by using a Firmware Restoration CD available from Apple. (Apple supplies the firmware as a download; you supply the CD.)

When Apple removed the CD/DVD drive from Mac models, they realized that an alternate method of recovering from a corrupt firmware installtion was needed. Apple could have provided the firmware restore system on a bootable USB flash drive, but instead the firmware recovery process is rolled into the Recovery HD hidden partition that is now included with all new Macs.

Even better you can use the following tips to create your own Recovery HD on any volume, including a handy USB flash drive you can carry around with you​.

If you have a late model Mac that does not have an optical drive you do not need the firmware restoration software. Your Mac is able to recover on its own from a firmware update error.

In order to ensure that you never have to take your Mac to a service center just to have the firmware restored, I've collected links to the firmware restoration images on the Apple website. These files will restore your Mac to working condition; however, before you can use these files, you must copy them to a CD or DVD. Then, if something goes wrong during a firmware update, you can restart your Mac from the Firmware Restoration CD and your Mac will replace the corrupt firmware with the known good version.

Get Your Mac's Model Identifier

There are currently 6 different Firmware Restoration files that cover various Mac models. In order to match your Mac with the correct file, you need to know your Mac's Model Identifier, which you can find by performing the following steps.

From the Apple menu, select About This Mac.

Click the More Info button.

If you're using OS X Lion or later, click the System Report button. If you're using an earlier version of OS X, continue from the next step.

The System Information window will open, displaying a two-pane view.

In the left pane, make sure that Hardware is selected.

You'll find the Model Identifier near the top of the right pane, under Hardware Overview.

The Model Identifier will be your Mac's model name with two numbers separated by a comma. For instance, my 2010 Mac Pro's Model Identifier is MacPro5,1.

Write down the Model Identifier and use it to find the correct Firmware Restoration file for your Mac.

Which Mac Firmware Restoration File to Download?

Firmware Restoration 1.8 - MacPro4,1, Xserve3,1

Firmware Restoration 1.7 - iMac4,1, iMac4,2, MacMini1,1, MacBook1,1, MacBookPro1,1, MacBookPro1,2, MacBookPro3,1

Firmware Restoration 1.6 - Xserve2,1, MacBook3,1, iMac7,1

Firmware Restoration 1.4 - iMac5,1, iMac5,2, iMac6,1, MacBook2,1, MacBookPro2,1, MacBookPro2,2, MacPro1,1, MacPro2,1, Xserve1,1

If you don't see your Mac model number in the above list, you may have an Intel Mac that doesn't have any firmware updates available. Newer Intel Macs don't need a restoration image.

Creating the Firmware Restoration CD

Before you can restore your Mac's firmware to its original state, you must first create a Firmware Restoration CD. The following steps will take you through the process.

Download the appropriate Firmware Restoration version from the list above.

Launch Disk Utility, located at /Applications/Utilities.

Click the Burn button in Disk Utility's toolbar, or select Burn from the Images menu.

Navigate to the Firmware Restoration file on your Mac; it will usually be in the Downloads folder. Select the file (a typical name is EFIRestoration1.7), and then click the Burn button.

Insert a blank CD or DVD (CDs are large enough to hold the data, so it's not necessary to use a DVD).

After you insert the CD, click the Burn button.

The Firmware Restoration CD will be created.

Using the Firmware Restoration CD

Ensure that your Mac is powered from an AC outlet; do not attempt to restore the firmware on a laptop while it's running under battery power.

If your Mac is on, power it off.

Press and hold the power on button your Mac until either the sleep light blinks three times fast, then three times slow, then three time fast (for Macs with sleep lights), or you hear three rapid tones, then three slow tones, then three rapid tones (for Macs without a sleep light).

Still holding the power button, insert the Firmware Restoration CD into your Mac's optical drive. If you have a tray-loading optical drive, gently push the tray closed after inserting the CD.

Release the power button.

You will hear a long tone, which indicates that the restoration process has started.

After a short delay, you'll see a progress bar.

Do not interrupt the process, disconnect power, use the mouse or keyboard, or shut down or restart your Mac during the restoration process.

When the update is complete, your Mac will automatically restart.