How To Use Apple Diagnostics
While Mac systems are extremely stable generally, they too can run into serious software or hardware problems. If your Mac is experiencing a serious malfunction that you believe is caused by a failing hardware component, you might want to run Apple Diagnostics. This may help you identify the root cause of the issue without having to go to a specialized store or Apple service.
Running the Apple Diagnostics
Before we start, we should mention that on older systems (Mac devices built before 2013) the feature is called Hardware Tests while newer systems have it labeled as the Apple Diagnostics. Functionally, however, they are virtually identical. Also, according to Apple's own recommendations, users should print the company's support instructions for running these tests, just in case.
- On desktop-based systems, the first step will be to disconnect all external drives and hardware devices. Keep the keyboard, mouse, display, and any speakers connected, though.
- Go to the Apple menu and select 'Restart.'
- While the Mac is booting, press and hold the D key on your keyboard.
- Apple Diagnostics should start automatically. When the process is completed, the user will be presented with a list of the encountered problems.
Common Codes for Hardware Issues
Users can either follow the on-screen instructions presented by Apple Diagnostics or opt to leave the rest to presumably more qualified people by contacting Apple support or an Apple Authorized Service Provider. No matter what you choose, making a note of the codes displayed by Apple Diagnostics might come in handy. Here is a list of common codes and their meaning:
4AIR - Wi-Fi, a failure of the AirPort wireless card
4HDD - Hard disk or SSD
4IRP - Logic board
4MEM - Memory (RAM)
4MHD - External disk
4MOT - Fans
4PRC - CPU
4YDC - GPU