Common Used iPhone Defects and How to Spot Them Before You Pay

Most losses in used iPhone trade are not fraud — they are defects nobody looked for until the lot was paid for. This guide maps the defect classes that matter, how to detect each one, and how to turn findings into grade language and claims.

Why defects cluster by source

Trade-in lots, refurbished lots and mixed container stock fail in different ways. Trade-in units usually carry original parts with battery wear; refurbished units may carry replaced screens or batteries with readings that no longer match the hardware.

Knowing the source tells you which tests to weight. A lot described as untouched trade-in deserves heavy battery scrutiny; a refurbished lot deserves heavy display and parts-pairing scrutiny.

Display defects

The screen is the most expensive single component and the fault class buyers most often discover late. Test on a plain background, then repeat at full brightness:

• Dead or bright pixels: run solid colour slides and scan the whole surface.
• Burn-in and image ghosts: a mid-grey slide exposes static UI shadows.
• Ghost touch and digitiser faults: drag along every edge and corner.
• Non-genuine display notices: check the device's parts history and whether True Tone behaves normally.
• Uniformity faults: purple edges, patchy backlight, or flicker at low brightness.

The detailed display protocol sits in our screen inspection guide.

Battery and charging defects

Battery condition drives both grade and returns, which is why readings deserve suspicion rather than trust. Read battery health and cycle count on the device, then test behaviour:

• Swelling: place the unit on flat glass and check for rocking or a lifted screen edge.
• Unexpected shutdowns: the battery section of the settings history exposes these.
• Fast drain and heat: charge to full, use it hot for twenty minutes, watch the curve.
• Charging port: test both cable orientations and check for pin corrosion or a loose connector.
• Wireless charging: test on a pad and look for intermittent drops and excess heat.

Grading thresholds and the reasons readings drift are covered in our battery health thresholds guide and the battery grading framework.

Housing, camera and sensor defects

Physical faults are cheap to find and easy to under-report, so treat them as a grading discipline rather than a formality:

• Bent frames and gap openings: check with a straight edge; a lifted screen signals swelling or a repair.
• Back-glass cracks: cosmetic, but they move the unit down a grade in most markets.
• Cameras: rattle suggesting a failed stabiliser, dust or scratches on the lens, hunting autofocus.
• Face ID: register a face and lock and unlock repeatedly; a replaced module misbehaves immediately.
• Buttons, mute switch and haptics: each needs a physical test, not a visual one.

Water damage: the quiet disqualifier

Water exposure is the one defect class that cannot be priced away, because failures appear days after arrival. Look for the telltales before you buy:

• Liquid contact indicators inside the SIM tray area.
• Corrosion at the charging port, speaker grilles and visible board edges.
• Fogging inside camera lenses and staining along screen edges.
• Intermittent behaviour that disappears during a short test, then returns under load.

Units showing these signs belong in parts stock, not in working inventory, and they should be graded out rather than sold as functional.

Board-level and connectivity defects

The failures that cost the most are the ones that stop a unit booting or connecting. They are also the quickest to screen out:

• Boot loops: watch the start-up sequence and check logs for repeated panics.
• No service or missing identifiers: read the device identifiers in settings and compare with the tray label.
• Wi-Fi and Bluetooth range: test at distance, not while standing next to the router.
• Audio faults: record and play back a sample, testing earpiece and loudspeaker separately.

Defect atlas: fastest detection and commercial impact

How many units should you actually test?

Full per-unit testing is the standard for suppliers who publish per-unit data. Where you are buying on sampling, the sample has to be defensible:

• Take at least 10% of a mixed-grade lot, spread across cartons rather than the top layer.
• Test every unit in high-value grades, where one failure is expensive.
• Record results against the identifier so the sample becomes evidence instead of anecdote.
• Repeat the sample on each shipment; a single clean lot does not prove a process.

A short routine is a useful filter but not a substitute for subsystem testing — see the five-minute check for where it stops being enough.

Turn defect findings into grade language and claims

Defects only cost you money twice if they are described loosely. Put them where they belong, in the grade definition and in the contract:

• Write the failure classes you accept and the ones you reject, per grade.
• Price the risk: if a few percent of a lot is likely to fail, that belongs in your offer.
• Raise claims inside the window with per-unit evidence, photos and readings.
• Distinguish refurbished and repaired stock from untouched units in both directions. The language questions are covered in refurbished versus used.

Frequently asked questions