Common iPhone Issues and Their Causes

iPhones are well-engineered devices, but they operate in demanding conditions — dropped in pockets with keys, left in the sun, used while charging, and subjected to a lot of mechanical wear over years of daily use. Most faults that come through our workshop have recognisable causes rooted in either physical damage, component wear, or software state. This article walks through the most common issues we see and explains the mechanisms behind them.

Screen Damage and Display Faults

Cracked screens are the single most common reason people bring in an iPhone. The glass used on modern iPhones — Apple's Ceramic Shield on iPhone 12 and later — offers improved drop resistance compared to earlier generations, but it is not unbreakable. A direct impact on a corner or on a hard surface at an angle that concentrates force across a small area is still sufficient to crack it.

There are two layers to consider: the outer glass and the OLED or LCD panel beneath it. Cosmetic cracks in the outer glass don't necessarily indicate panel damage. However, if a drop causes internal display damage — visible as a black bleed, colour distortion, lines across the image, or complete loss of display — the OLED or LCD module itself has been affected. On most iPhones from the X series onward, the glass is laminated directly to the display panel, which means separating a cracked glass from a functioning panel without specialist equipment is not a standard consumer repair.

Touch Sensitivity Issues

After a drop, some users find the display still shows an image but touch input is erratic or absent. This typically means the digitiser — the touch-sensing layer integrated into the display assembly — has been damaged or its connector has been dislodged. A replacement display assembly restores both image and touch function.

Ghost Touch and Unresponsive Areas

Occasional erratic touch inputs with no physical damage can sometimes be traced to a partially failing display connector, condensation that has reached the board, or in some cases a failing display IC on the logic board. Genuine ghost touch (inputs registering with no contact) is relatively uncommon and usually indicates a hardware fault rather than a software problem.

Charging Problems

Charging issues come in several forms with quite different causes, so it's worth being specific about the symptom.

Phone won't charge at all

If the phone shows no response when connected to a charger, the first thing to check is the cable and the power source — a surprising number of "faulty phones" turn out to have faulty cables. If the cable and adapter are confirmed working on another device, the next most common culprit is lint or debris packed into the Lightning or USB-C port. The port connector sits at the bottom of a small cavity that accumulates pocket lint over time, and a sufficient buildup prevents the cable from seating fully. A gentle clean with a non-metallic tool resolves this in many cases.

If the port is clean and the phone still won't charge, it's likely that the charging port flex assembly has a hardware fault — either the port connector itself is damaged, or the TRISTAR/HYDRA charging IC on the logic board has failed. Tristar failure is more common on Lightning devices and typically requires microsoldering rather than a straightforward port replacement.

Intermittent charging

A connection that only works at certain cable angles usually indicates physical damage to the port pins — often from inserting a cable at an angle under force, or from using a low-quality cable whose connector is slightly out of specification. The spring-loaded pins inside the port can become bent or worn.

Slow or limited charging

If the phone charges but more slowly than expected, iOS is sometimes limiting charging due to battery temperature. During hot weather or after intensive use, iOS intentionally reduces charge rate to protect the battery. This is normal behaviour. Persistent slow charging regardless of temperature warrants a closer look at both the cable specification and the charging port condition.

Battery and Power Issues

Beyond the degradation discussed in our battery health article, there are a few battery-related faults worth understanding separately.

Rapid drainage

A phone that loses charge unusually quickly isn't always a battery problem. Background app activity, location services running continuously, a display set to always-on, or a faulty app that keeps a CPU core active can all cause excessive drain. If battery health is above 85% but drain is excessive, running through iOS battery analytics under Settings → Battery is worth doing before assuming a hardware fault.

Swollen batteries

As covered in the battery health article, gas buildup within a degraded cell can cause it to physically expand. The visual sign is a screen beginning to lift at one edge or a small raised area on the rear panel. A swollen battery is not safe to leave in place — it's placing mechanical stress on the display and internal components and should be addressed.

Camera Faults

iPhone cameras involve several distinct hardware components, and faults in any one of them produce different symptoms.

Blurry images or autofocus failure

The main camera lens on most modern iPhones uses optical image stabilisation (OIS) — a mechanism that physically shifts the lens element to compensate for hand movement. This mechanism involves small magnets and a flexible assembly. After a significant drop, the OIS actuator can become stuck or damaged, resulting in a camera that can no longer focus correctly. In some cases the camera image appears to constantly shift or "swim" — this is a characteristic symptom of OIS damage.

Black screen on camera launch

If the Camera app opens but shows a black screen, this is frequently a connector issue — either the camera flex connector has been partially dislodged (sometimes by a previous repair) or the camera module itself has failed. On multi-camera phones, if one lens works and another shows black, it's usually the module for the non-functioning lens.

Green or purple tint

A persistent green or purple tint in images or on the live preview typically indicates damage to the image sensor. This can occur after liquid exposure or significant impact. It's a module-level fault — the camera module requires replacement.

Flash not working

The rear flash doubles as a torch, so it's easy to verify independently. A torch that doesn't activate suggests a fault with the flash flex or flash driver circuit. If the flash works via the torch but not during photo capture, the issue is more likely software or a camera module fault rather than the flash hardware itself.

Speaker and Microphone Issues

iPhones have multiple speakers and microphones, which complicates diagnosis.

Muffled or quiet audio

The most common cause of a suddenly quiet earpiece or speaker is simply debris — the speaker grille is small and accumulates lint, dust, and pocket material. A careful clean of the grille with a soft brush often resolves this without any hardware repair. If cleaning doesn't help, the speaker driver itself may have failed, or the speaker mesh may have sustained water damage that has dried but left residue on the driver cone.

No audio during calls

The earpiece at the top of the phone is a separate component from the loudspeaker at the bottom. If the earpiece is silent during calls but speakerphone works normally, the earpiece receiver or its connection has failed. This is a straightforward component replacement in most cases.

Microphone not picking up voice

iPhones have three microphones — at the bottom, the front face, and the rear. Call audio uses the bottom microphone primarily; video recording uses a combination depending on the model. If callers can't hear you, confirming which microphone is affected helps narrow the diagnosis. The bottom microphone is on the same assembly as the charging port flex on many models, so charging port damage can affect it.

Face ID and Biometric Failures

Face ID relies on a cluster of sensors in the TrueDepth camera system — a dot projector, infrared camera, flood illuminator, and front-facing camera — that must all function together. This system is calibrated to a specific device at the factory level.

If Face ID stops working after a drop, it's usually because the TrueDepth module or its connector has been damaged. If it stops working after a screen replacement, it's most likely because either the ear speaker/Face ID flex cable was damaged during disassembly, or — on iPhone 13 series — the Face ID module was not transferred correctly to the replacement screen. On iPhone 13 and later, the Face ID components are paired to the logic board and cannot be substituted with another module; a damaged TrueDepth camera results in permanent Face ID loss until an Apple service repair is performed.

Water Damage

Modern iPhones carry an IP67 or IP68 rating, which indicates resistance to fresh water at specified depths and durations under controlled test conditions. These ratings do not mean waterproof in all circumstances, and they diminish over time as seals age and if the phone has been dropped or repaired previously.

Liquid ingress causes damage through two primary mechanisms: short circuits from current flowing through unintended paths while the device is powered, and corrosion developing on connectors and board components as the liquid dries and leaves behind mineral deposits. Immediate power-off (if the device is still functioning) and professional drying reduces the risk of corrosion taking hold, but outcomes vary considerably depending on the type of liquid and the extent of ingress.

Connectivity Problems

Wi-Fi and Bluetooth dropout

Intermittent Wi-Fi or Bluetooth that persists across different networks, different iOS versions, and after a full device reset typically points to a hardware fault with the WLAN/Bluetooth chip or its associated antenna connections. Antennas in iPhones pass through the sides of the frame; significant impact damage in the right location can affect the antenna connections without visibly cracking the housing.

No cellular signal

A permanent "No Service" or "Searching" state that persists after re-inserting the SIM and resetting network settings is usually a baseband modem issue or damaged cellular antenna. Baseband modem faults often require board-level diagnostics to confirm.

Summary

Most iPhone faults have clear physical explanations rooted in component wear, impact damage, or liquid exposure. Understanding the mechanism behind a fault makes it easier to have a productive conversation with whoever is carrying out the diagnosis and repair, and helps avoid solutions that treat symptoms rather than causes. If you're uncertain what's causing a specific problem with your device, a diagnostic is the most reliable way to get an accurate picture before deciding on the appropriate course of action.