iPhone testing guide

Battery

1. 1Open Settings > Battery > Battery Health (on newer iOS: Battery Health & Charging).
2. 2Read Maximum Capacity. Apple designs iPhone batteries to keep up to 80% of their capacity after a set number of charge cycles, so a figure well under 80% means a worn battery.
3. 3Read the message under Peak Performance Capability. A warning about performance management or a battery that needs service means a replacement soon.
4. 4Newer iPhones on a recent iOS also show the cycle count on this screen. If you do not see it, your model does not show it.

Tip. Battery health is not shown for a battery that Apple cannot verify. If you see "Unable to verify this iPhone has a genuine Apple battery", the percentage may not be accurate.

Parts and Service History

1. 1Open Settings > General > About (iOS 15.2 or later).
2. 2Scroll to Parts and Service History. It appears when a part was replaced.
3. 3Genuine means a genuine Apple part and process. Used means a genuine battery that was taken from another iPhone. Unknown means Apple cannot verify the part: it may be non-genuine, not linked after the repair, or modified.
4. 4If the screen says nothing, no replaced part was recorded.

Warning. An Unknown screen, battery or camera is not always bad, but it needs an honest answer and a lower price.

Activation Lock and Find My

Activation Lock ties the iPhone to the previous owner's Apple Account. A locked iPhone is a brick for you.

1. 1Ask the seller to sign out of Settings > [name] > Sign Out, and turn Find My off.
2. 2Ask the seller to erase it: Settings > General > Transfer or Reset iPhone > Erase All Content and Settings, in front of you.
3. 3Set it up as new. If it asks for an Apple Account or password that is not yours, it is locked. Do not buy it.
4. 4Check that you can reach the Home Screen without any email, code or password from the seller.

Warning. Apple removed its public Activation Lock checker in 2017. There is no website that can tell you the lock status. The only safe check is the erase-and-set-up test in person. Never accept a promise that the seller will remove it later.

Display and hardware

1. 1Dead and stuck pixels: use solid colour screens (see Display Testing).
2. 2Green lines, flicker or a dark line on the edge.
3. 3Touch every corner and drag an icon across the whole screen.
4. 4True Tone: Settings > Display & Brightness. If the switch is missing on a model that has it, the screen may have been replaced.
5. 5Face ID: set it up, then unlock. Touch ID: add a finger and unlock three times.
6. 6Front and rear cameras, flash, speakers, microphone and earpiece (see the Camera and Audio guide).
7. 7Plug in the charger and a cable: it must charge without wiggling. Check the buttons, silent switch and vibration.
8. 8Wi-Fi, Bluetooth and a mobile call with a SIM (see Network and Physical).

Serial number and warranty

The coverage page shows the model, the warranty and whether the device is registered as sold. It cannot tell you if the phone is stolen, blocked, or Activation Locked. The model shown must match the phone in your hand.

1. 1Settings > General > About: note Model Number and Serial Number.
2. 2Compare them with the box label and the invoice.
3. 3Enter the serial number on Apple's coverage page.

Common questions