MacBook Pro A1708 & A1989 Serial Check: Two vs Four Thunderbolt Ports

A1708 vs A1989: the port count tells the story

The cleanest way to separate these two machines is by the chassis layout. The MacBook Pro A1708 is the 13-inch model without Touch Bar, and Apple gave it two Thunderbolt 3 USB-C ports on the left side only. The A1989 is the 13-inch Touch Bar model, and it carries four Thunderbolt 3 ports, two on each side. If a listing claims “Touch Bar” but the shell clearly shows only two ports, something is off before you even look at the serial.

That said, sellers often mix model identifiers, marketing language, and upgraded logic boards in a single listing. A1708 and A1989 share the same general 13-inch footprint and can look close enough in photos to fool casual buyers. The serial number is the backbone of the verification process because it links the machine to Apple’s factory records, AppleCare coverage, and the exact configuration shipped from the factory. This is why a macbook pro a1708 serial number check matters more than a vague “13-inch MacBook Pro” description.

In the field, I also pay attention to the keyboard row and the Touch Bar. A1708 uses the function-key row; A1989 replaces it with the Touch Bar and Touch ID power button. If a machine is advertised as “A1989” but boots with physical function keys, or if the port layout does not match the story, the seller is either careless or hiding a hardware transplant. For buyers, the safest habit is simple: confirm the serial, confirm the ports, confirm the keyboard layout, and then confirm the model in software.

Where to find the serial on the MacBook Pro without trusting the seller

On a healthy Mac, the first stop is the Apple menu. Open About This Mac on older macOS versions or System Settings > General > About on newer builds. The serial number appears there, and it should match the value reported in System Information. If the machine can boot but the seller refuses to show this screen, treat that as a warning sign. A properly represented Mac should not need storytelling to reveal its identity.

Terminal gives a more defensible check. Run system_profiler SPHardwareDataType and look for Serial Number (system). For a second opinion, use ioreg -l | grep IOPlatformSerialNumber. Those two outputs should align exactly. If they do not, you may be looking at a machine with incomplete firmware data, a board swap, or a manipulated presentation. I like to compare those results against the serial printed on the original retail box, if the seller still has it, because box labels often preserve the original factory identity.

Physical inspection still matters. The bottom case on many MacBooks carries regulatory markings and often a printed serial or model family identifier depending on revision. The key is not to rely on the bottom case alone; bottom shells get swapped. I also check the Apple ID device list at appleid.apple.com when the seller claims the unit has been removed from an account. If it was ever tied to their Apple ID, they should be able to show the device is gone before money changes hands.

Terminal and recovery-mode checks that expose mismatches fast

If the Mac boots, I prefer a layered check. Start with the GUI, then use Terminal, then verify the same serial from Recovery if needed. On Intel models such as A1708 and A1989, you can reboot into macOS Recovery and open Utilities > Terminal. From there, you can repeat the same commands even if the main operating system is unstable, encrypted, or partially corrupted. That matters when a seller says “the machine just needs a reinstall” but you suspect the board identity may be compromised.

Recovery mode is also useful when a system won’t fully enter macOS but still has working firmware. If Apple’s native tools can see the serial in Recovery but the normal desktop cannot, the problem may be software. If the serial is missing everywhere, the suspicion shifts toward the logic board or its serialized firmware state. In practice, this distinction saves time. It also prevents buyers from overpaying for a machine with a non-original main board that has not been properly provisioned.

For administrators and power users, I also check system_profiler SPHardwareDataType in verbose mode through a local shell and then compare the machine’s model identifier with sysctl hw.model. The two should make sense together. A1989 units typically present as MacBookPro15,2 in software, while A1708 commonly maps to the non-Touch Bar 13-inch family. If the model identifier and the physical design disagree, stop there and investigate the board history before you trust any remaining diagnostics.

Why missing serials usually mean a logic board swap or bad serializer work

When a Mac shows “System Serial Number Unavailable,” it is rarely a mystery in the purest sense. In the real world, the most common cause is a logic board replacement that was not finished correctly. Apple uses proprietary serialization tools during authorized repairs, and when a third-party shop installs a board without proper provisioning, the computer can lose the serial identity that services like iCloud, iMessage, FaceTime, and AppleCare depend on. That is where the terms BBS and AST2 come up in repair conversations.

Apple’s Blank Board Serializer and service workflows are not hobby tools. They are part of an authorized process. If a board was swapped in a non-authorized shop and never serialized properly, the machine may still boot, but account authentication can fail in odd ways. I have seen machines that appear healthy on the surface yet cannot sign into Apple services cleanly or cannot pass coverage checks. This is why the macbook pro a1989 serial lookup should never be used as a one-line verdict. It is a starting point, not the whole case.

If you encounter a missing serial or a questionable board history, the legitimate fix is to take the machine to an Apple Authorized Service Provider or Apple Store. They can inspect the board pedigree, verify part compatibility, and determine whether the issue stems from an incomplete service workflow. Buyers should avoid “fixes” from resale sellers who promise they can patch the serial later. That sort of promise is a red flag, not a repair plan.

Pre-owned inspection steps that actually protect buyers

For a used A1708 or A1989, I insist on a live, in-person boot. Do not accept screenshots alone. Power the machine on, connect it to Wi-Fi, and move through Setup Assistant if it is freshly erased. That is when remote management surprises show up. If the device was enrolled in corporate MDM/DEP, it may phone home during activation and force a management profile before you ever reach the desktop. If you are buying from a stranger, you want to see the machine reach a clean setup path without an organization banner appearing midstream.

Activation Lock deserves equal attention. Before purchase, sign out of all Apple services, erase the Mac properly, and confirm that Setup Assistant does not ask for a prior owner’s Apple ID. You can also check coverage at checkcoverage.apple.com using the serial number. A valid serial may still be locked to another account, but a coverage result can confirm the serial is structurally valid and recognized by Apple’s systems. If the seller refuses to erase the device in front of you, assume there is a reason.

I also inspect the case for liquid evidence and abuse. The Liquid Contact Indicators are not always easy to reach, but visible corrosion near ports, distorted screws, or a swollen trackpad area can tell the story. Battery health matters too. In System Report > Power, check cycle count, condition, and full charge capacity. A machine with a suspiciously low cycle count but obvious wear may have had its battery replaced or its history hidden. That is not automatically bad, but it needs a price adjustment and a closer look at the rest of the hardware.

Testing Thunderbolt, USB-C, battery, and diagnostics like a bench tech

Because the A1708 and A1989 are defined so strongly by port count, I always test the buses, not just the metal openings. Bring a known-good USB-C flash drive or external SSD and verify data transfer on every port. A power-only port is a very different problem from a damaged Thunderbolt controller. Plug in an external display if you can, or at least a dongle that reports correctly in System Information. You want the machine to negotiate power, data, and accessory detection cleanly on both sides of the chassis if it is an A1989.

Apple Diagnostics should be part of the handoff. On Intel Macs, hold Option-D at startup; on Apple silicon, you would hold Power to startup options and then use Cmd-D, though that does not apply to these Intel models. Diagnostics can surface battery, thermal, and accessory errors that casual buyers miss. If a seller insists the Mac is perfect but refuses to let you run diagnostics, the refusal itself is information. A good machine survives testing.

For a deeper hardware read, open System Information and review Thunderbolt/USB sections. Look for clean bus enumeration and sensible device IDs. If one port only charges, if one side drops devices, or if the ports show intermittent negotiation, you may be dealing with board-level damage rather than simple dirt. This is where a serial check and a physical inspection converge: a machine that has been through board work, liquid exposure, or shell swapping often leaves clues in the buses long before it fails outright.

A1708 vs A1989: practical diagnostic comparison

This table is where the listing language gets grounded in hardware reality. When a seller says “same as the one with four ports,” that is not a specification. It is a guess. The port arrangement, model family, and serial data should all line up with the same machine. If they do not, use our MacBook Serial Checker to decode production date, exact model family, technical specs, and AppleCare status before you commit to a purchase.

Official Apple references and the best way to close the loop

Apple’s own support pages remain the most reliable public source for serial validation and warranty status. Start with support.apple.com for model-specific documentation, then verify coverage at checkcoverage.apple.com. If the serial comes back valid, the result should still be treated as one piece of a larger inspection. A valid serial does not erase a bad board swap, a locked account, or a corporate enrollment record.

For buyers, the safest path is a three-part confirmation: the machine must boot cleanly, the serial must be consistent across software and chassis, and the activation path must be free of MDM and Activation Lock. For IT administrators, the same rule helps during intake. Record the serial, validate the model family, and document the results before the device is put into service. That small discipline prevents expensive surprises later.

When a seller’s story is neat but the evidence is messy, trust the evidence. A1708 and A1989 can be easy to confuse in a quick photo, but they are not hard to separate when you use the serial, the ports, and Apple’s own tools together. That is the standard worth keeping.