How to Check a Used Samsung for FRP Lock Before You Buy

Short answer

FRP (Factory Reset Protection) is Google’s anti-theft lock. It ties an Android phone to a Google account, so a thief who wipes the phone still can’t use it. The same thing catches honest buyers: if the seller’s account is still on the phone, you may be stuck at setup with no way forward.

There is no public website that tells you whether a phone has FRP on. An IMEI check won’t show it either, because IMEI checks look at theft and blacklist reports, not account sign-ins. The only reliable test is on the phone: check the account screens, watch a reset, and run setup yourself before any money changes hands. Keep our used phone checklist open while you do it.

The three locks on a used Galaxy

Most guides stop at FRP. On a Samsung, there are three separate things to rule out, and each one has a different owner.

• Google FRP. Tied to the seller’s Google account. It applies to Android 5.1 and later, so nearly any Galaxy you will see for sale. It blocks setup after a reset.
• Samsung Reactivation Lock. Tied to the seller’s Samsung account through Find My Mobile. It also blocks setup after a reset, and it is independent of FRP. A phone can pass the Google check and still be locked to Samsung.
• Knox Guard. This one is not tied to the seller’s personal account at all. Samsung describes it as a cloud service that lets a business or lender message and lock a device, including as a last-resort step for missed payments. On a locked phone, factory reset is one of the features it restricts. It is found on financed and company phones, on Android 11 or later.

You may also see “Knox” mentioned in a different sense. The Knox warranty bit is a flag showing whether the phone’s software has been modified. Swappa points out it isn’t an account lock and has nothing to clear, though a tripped bit can affect warranty and some banking or work apps.

Step 1: Check the phone before anyone resets it

Do this first, while the phone is still unlocked and the seller is with you. Menu names change between One UI versions, so if a path below doesn’t match, type the name into the search bar at the top of Settings.

1. Open Settings → Accounts and backup → Accounts (on some phones, Settings → Accounts). The list should show no Google account and no Samsung account.
2. If either is there, ask the seller to tap it and choose Remove account. They will need their password, which is a useful test: someone who can’t enter it may not be the owner.
3. Open Settings → Biometrics and security → Find My Mobile, or search Settings for Find My Mobile. It should be off.
4. Ask the seller to unlock the phone with its PIN or pattern. Google says a phone with a Google account and a screen lock has device protection on, and that a reset from Settings asks for that screen lock.
5. Note any message saying the phone is managed by a company or organization. Notebookcheck’s advice is that IT must release such a phone, and a factory reset won’t help.

Step 2: Do the reset test

This is the check that matters. The account screens tell you what the seller did; the setup screen tells you what the phone will do to you.

1. With accounts removed, have the seller factory reset the phone from Settings. Searching Settings for factory is the quickest way to find the option.
2. When it restarts, go through setup yourself and connect to Wi-Fi.
3. Watch for a screen asking you to verify an account that was previously on the phone, or for a Samsung account prompt you didn’t expect.
4. Sign in with your own Google account. If that works, FRP is clear.
5. Sign in with your own Samsung account too, if you use one. Then finish setup and reach the home screen.
6. Restart the phone once more and confirm it opens normally.

Why reset at all, if the accounts are gone? Because the way a phone was erased changes what it asks for. Google says a reset from Settings asks for the screen lock, a reset from recovery mode asks for the PIN or the Google account, and a remote reset through Find Hub asks for the Google username and password. A phone that was already wiped when you arrive tells you nothing until you run setup. If it shows the welcome screen, don’t treat that as proof. Run setup to the end before you pay.

Buying online or by mail

You can’t watch a reset through a listing, so you are relying on the seller’s evidence and your payment protection.

• Ask for screenshots of the Accounts screen and the Find My Mobile screen. Swappa suggests this for remote sales.
• Ask for a short video of the phone reaching the home screen after a reset. Swappa warns this isn’t foolproof, so treat it as a filter and not a guarantee.
• Get written confirmation that the seller removed the phone from every account.
• Ask for the IMEI and run it through a stolen phone check. It covers a different risk, and you need both.
• Pay with a method that has buyer protection, and check how long you have to open a claim. Don’t use cash apps or bank transfer with a stranger.
• If the phone is financed, ask for proof it is paid off, such as a receipt or a carrier confirmation. EcoATM reports that a Knox Guard lock can appear days or weeks after a sale, so a phone that works today is not proof on its own.

What your results mean

• No accounts listed, reset done, your account signs in, home screen reached: FRP and Reactivation Lock are clear.
• “Verify your Google account” or a request for the old account: FRP is active. Stop. The seller must clear it.
• Google step passes, then a Samsung account prompt for the old owner: Reactivation Lock is on. The seller must clear it.
• A payment reminder that can’t be dismissed: likely Knox Guard, which Samsung says can show these. The lock belongs to the company that set it, so a new owner has little chance of getting it released.
• “Managed by” a company at startup: a former work phone. Buy only if the seller can show it has been released.
• Seller won’t reset the phone or says the password is forgotten: walk away, whatever the price.

If the phone is already locked

1. Contact the seller first. Usually they can fix this without touching the phone. For Google, they sign in at myaccount.google.com, open Security, and remove the phone from their devices. For Samsung, they sign in at findmymobile.samsung.com and remove the device.
2. If they go quiet, open a claim. Use your marketplace or payment platform, and do it before the deadline.
3. Don’t buy an FRP bypass. Swappa calls these tools inconsistent and says many are scams, and Notebookcheck reports that Android 15 made the protection harder to bypass. Bypassing a lock on a phone that may be stolen can also leave you holding it when the report catches up.
4. Don’t expect Samsung or a carrier to clear it for you. Swappa says Samsung can’t bypass Reactivation Lock for a buyer, and that a carrier can’t remove FRP.

When there is no seller and no claim left, the phone may be a total loss. Parts value is usually all that remains, so get a price from a repair shop before you spend more on it.

Once the locks are clear

A clean account check says nothing about the hardware. Run the free phone diagnostic in the browser, put your own SIM in and test a call, and work through our guide to testing a used phone. Buying an iPhone instead? The same idea applies with Activation Lock, covered in our used iPhone guide.

The lock checks are the same in the UK, Canada and Australia. What differs is the IMEI lookup and your rights. UK buyers can use CheckMEND, which also looks at outstanding finance.