tool built into modern Macs, ASD provides low-level EFI and OS-based testing. Supported Mac Models
If you have stumbled upon the specific code , you are likely staring at a diagnostic log, a repair ticket, or a system information screen. You are no longer asking "What is broken?" but rather, "What does 3S155 mean, and how do I fix it?"
It won't help you with a 2023 MacBook Pro (those use AST 2 over the internet), but for keeping a 2011 MacBook Pro alive against all odds? There is no substitute.
Let’s say you run the "Extended" test on a 2011 MBP.
Apple Service Diagnostics - 3s155 __exclusive__ Jun 2026
tool built into modern Macs, ASD provides low-level EFI and OS-based testing. Supported Mac Models
If you have stumbled upon the specific code , you are likely staring at a diagnostic log, a repair ticket, or a system information screen. You are no longer asking "What is broken?" but rather, "What does 3S155 mean, and how do I fix it?" Apple Service Diagnostics - 3S155
It won't help you with a 2023 MacBook Pro (those use AST 2 over the internet), but for keeping a 2011 MacBook Pro alive against all odds? There is no substitute. tool built into modern Macs, ASD provides low-level
Let’s say you run the "Extended" test on a 2011 MBP. tool built into modern Macs