iPhone Diagnostics: Quick Tips to Spot and Fix Common Issues

Ever wonder why your iPhone feels slow, drains battery fast, or shows weird sensor glitches? You don’t need a pricey service centre to find out what’s wrong. With a few built‑in menus and secret codes, you can run basic diagnostics right from your device.

Check Battery Health and Usage

First thing most people check is the battery. Open Settings → Battery → Battery Health & Charging. Here you’ll see the maximum capacity percentage and whether the battery can support peak performance. If the number drops below 80 %, it’s a sign the cell has aged and may need a replacement.

For deeper insight, dial *#*#4636#*#* (or *#*#3282#*#* on some models). The hidden menu shows real‑time voltage, temperature and charge cycles. Compare the voltage when the phone is idle (around 3.7 V) to the voltage while charging (3.9–4.0 V). Large swings indicate a faulty battery or charger.

Run Sensor and Hardware Tests

iPhones hide a diagnostics suite that can test the accelerometer, gyroscope, proximity sensor and more. Type *#06# to view the IMEI, then go to Settings → Privacy → Analytics & Improvements → Diagnostics & Usage and enable “Share iPhone Analytics.” After a reboot, tap the “Analytics Data” list and look for entries starting with DiagnosticLog. Those logs contain sensor readouts you can compare against normal ranges with a quick web search.

If you suspect the speaker or microphone is off, open the Voice Memos app and record a short note. Playback will confirm if the mic works. For the speaker, play any song and watch for distortion. No sound? Try restarting the phone, then check Settings → Accessibility → Audio/Visual for any mute settings.

When your iPhone won’t boot or gets stuck in a boot loop, hidden recovery modes come to the rescue. Hold Power + Volume Down for ten seconds to force a hard reset. If that fails, connect the phone to a computer and launch iTunes (or Finder on macOS). You’ll see options for Recovery Mode, DFU Mode, and even “Update without data loss.” These modes let you reinstall iOS without wiping your data—perfect for software bugs.

Lastly, keep an eye on network and Wi‑Fi issues. Dial *#*#4636#*#* again and choose “Phone info” to see signal strength in dBm. Anything weaker than -90 dBm is a weak signal. Switching to 5 GHz Wi‑Fi (if your router supports it) often solves slow browsing.

By using these built‑in tools, you can diagnose most everyday iPhone problems without opening the device or spending money on third‑party apps. If anything still feels off after your checks, it’s time to visit a certified service centre for a full hardware inspection.