Refurbished iPhone Face ID test guide, quick checks, common faults, and when to return it

Meta description: Learn the iPhone Face ID test for refurbished iPhones, run quick checks to spot TrueDepth faults, and know when to return it under UK rights and warranty.

Buying refurbished iPhones can feel like finding a solid car with a fresh MOT. It looks great, it’s priced right, but you still want to turn the key and listen for odd noises.

Face ID is that “turn of the key” moment. If it works, day to day use feels effortless. If it doesn’t, your “bargain” can turn into a passcode-only slog.

This guide walks you through an iPhone Face ID test you can do in minutes, what common faults look like on used iPhones and second-hand iPhones, and the clear signs it’s time to send the phone back.

Before you start: what a “good” Face ID experience feels like

Face ID should be boring in the best way. You raise the phone, it unlocks, you don’t think about it again. On a properly tested refurbished device, that’s the baseline.

A quick reality check first:

• Face ID is hardware-based. It relies on the TrueDepth camera system in the notch or Dynamic Island area. If key parts were damaged (often by drops, liquid, or poor-quality repair), software tweaks won’t save it.
• Refurbs vary by seller. Some “cheap iPhones” listings are properly tested and graded, others are just iPhones for sale with a wipe and a prayer. Buying from a UK refurb specialist with a returns window and warranty matters.
• Accessories can cause false alarms. A thick screen protector, a badly aligned case lip, or grime around the notch can make Face ID act moody.

If you’ve bought from a retailer like Used Mobiles 4U, you’ll usually have time to test properly. Don’t wait until you’ve moved everything across and binned the packaging. Test first, then settle in.

The 5-minute iPhone Face ID test (quick checks that catch most issues)

Do these checks in good indoor light, then again in slightly dimmer light, like a hallway. Face ID should cope with both.

1) Confirm Face ID can be set up

Go to Settings, Face ID & Passcode. If Face ID is missing entirely, or you see messages like “Face ID is not available”, treat that as a serious red flag on used iPhones.

If you need Apple’s official setup steps, follow Apple’s guide to using Face ID. If the setup circle won’t complete, don’t keep fighting it for an hour. That’s often the point where a return makes more sense than “trying one more thing”.

2) Run a clean unlock test

Lock the phone, then wake it and look at it naturally.

A healthy result looks like this: the padlock icon opens quickly, then a swipe takes you home. If you keep getting the passcode prompt after one or two attempts, note the pattern. Is it worse at an angle? Worse in low light? Random?

3) Test “Require Attention” and portrait consistency

In Face ID & Passcode, turn Require Attention for Face ID on. Then try unlocking while looking at the screen, and again while deliberately looking away.

This checks whether the sensors are reading your face properly, not just doing a sloppy match. If it unlocks while you’re clearly not looking, that’s not normal behaviour.

4) Test Face ID in real actions, not just unlocking

Use Face ID in at least two places:

• App Store download (even a free app)
• Password AutoFill or unlocking a banking app (if you already use one)

Unlock-only tests can pass even when Face ID is flaky in apps.

5) Check the notch area like you’d check a windscreen

Wipe the top of the display with a microfibre cloth. Look for:

• A protector covering the sensor area
• Cracks near the top edge
• Dust packed into the earpiece grille

It sounds basic, but a surprising number of “Face ID problems” are really just “Face ID can’t see”.

Common Face ID faults on refurbished iPhones (and what to do next)

Some Face ID issues are minor. Others are classic signs of a handset that’s had a rough life before refurbishment.

Here’s a quick guide to what the symptoms usually mean:

What you see	Likely cause	Best next step
“Face ID is not available” in Settings	TrueDepth hardware fault, often from drop, liquid, or parts mismatch	Return it, don’t accept “reset and update” as the only fix
Setup won’t complete (can’t finish the face scan)	Sensor obstruction, damaged module, or poor prior repair	Try cleaning and removing protector, if it still fails, return
Works sometimes, fails more in low light or angles	Dirty sensor area, failing components, or misaligned screen replacement	Quick clean test, if inconsistent, arrange return or warranty

A very common refurb story is the “screen replacement surprise”. If a previous owner fitted a low-quality display, the alignment around the top sensor area can be slightly off. Face ID might still half-work, like a door lock that only turns if you jiggle the key. That’s not what you want long term.

If you’re troubleshooting, Apple’s own checklist is worth a read, especially for basic setting and iOS checks: Apple’s steps if Face ID isn’t working. If you’ve done the sensible steps (update iOS, clean sensors, re-add Face ID) and it still misbehaves, stop there.

Also watch for “too good to be true” bundles. Some second-hand iPhones are sold cheaply because Face ID is already broken, then dressed up as “grade A” elsewhere. At that point, it’s not just an annoyance, it affects security and resale value.

If Face ID failure is a deal-breaker and you need a budget handset quickly, you might prefer Cheap Android Phones with a fingerprint reader, or a used Samsung model where the biometric system is still reliable. That’s not a knock on iPhone, it’s just being practical.

When to return it (and how to make the return painless)

If Face ID is broken on arrival, treat it like a cracked charger you’ve just unboxed. It’s not your job to “make it work”. In the UK, you also have clear protections when goods aren’t as described or are faulty.

Return it if any of these are true:

• Face ID can’t be set up at all.
• It only works intermittently, even after cleaning and removing any screen protector.
• The phone shows Face ID errors during setup or in Settings.
• You suspect liquid damage or poor repair (especially if the top area looks misaligned).

Before you pack it up, take two minutes to save evidence. It can speed up the support conversation:

• A short video showing the Settings message or failed setup
• A screenshot of Face ID options missing or greyed out
• A note of the date you received it and what you tried

If you’re within the returns period, use it. If you’re outside it but within warranty, raise it as a fault straight away. Reputable refurb sellers build this into the process, especially if you bought a graded device expecting full function.

Once you’re sorted, don’t forget the other side of the upgrade. If you plan to sell your tech, sell old iPhone, or trade-in iPhone models you’re replacing, do it promptly while value is higher. Many people also ask “can I recycle my old iPhone?” Yes, and if you’d rather keep it simple you can trade-in my old phone through a responsible programme rather than leaving it in a drawer.

Conclusion (plus FAQs)

A good iPhone Face ID test is quick, but it tells you a lot. If Face ID sets up cleanly, unlocks fast, and works inside apps, you’ve probably got a keeper. If it’s unavailable, inconsistent, or fails setup, returning it early is usually the smartest move, especially with refurbished purchases where you expect everything to function.

If you’re still shopping, stick to sellers with clear testing standards, UK delivery, and straightforward returns, like Used Mobiles 4U. Your future self will thank you every time your phone unlocks without a second thought.

FAQs {#faqs}

Can Face ID be fixed on refurbished iPhones?
Sometimes, but many Face ID failures are tied to TrueDepth hardware. If it’s dead on arrival, a return is often better than a repair attempt.

Is Face ID failure common on used iPhones?
It’s not the norm, but it’s common enough on heavily second-hand iPhones with prior drops, liquid exposure, or poor repairs, especially screen swaps.

Does a screen protector break Face ID?
A badly fitted or thick protector can interfere, especially if it covers the sensor area. Remove it and re-test before you assume a fault.

Should I keep a phone if Face ID only works sometimes?
No. Intermittent Face ID usually gets worse, not better. If it’s within your return window or warranty, act while you can.