iPhone Randomly Shuts Off Solutions

First Steps

Before trying the bigger solutions below, start with these basic steps:

Try a different charger or one you know works. Your phone might not be getting enough power to turn on.
Do a force restart. Check the guide for your phone model if you don’t know how to do this.
If your phone turns on, look for software or app updates. These might fix the problem.

Causes

1: Software Corruption or Conflict

Sometimes, your phone may stop working properly because something in its software has been damaged or changed. This can happen after a failed update, an app causing problems, or even a virus.

To fix this, you can try reinstalling the operating system. If your phone stays on long enough, you can do this through the settings menu. If not, you’ll need to use recovery mode.

Try updating first.
If the update doesn’t work, check your backups. If you have a recent backup or are okay with losing your data, you can restore your phone. This will erase everything on it. If you don’t want to erase your phone, skip the restore and try other fixes below.
If the update or restore fails and shows an error message, write it down. You can get more help by visiting the Answers forum and sharing the error message when asking for advice.

2: Faulty or Worn Battery

We all know that rechargeable batteries wear out over time. They lose their power and can even fail suddenly, causing your phone to shut down unexpectedly.

Here’s what you can do:

Check your battery health by going to Settings > Battery > Battery Health.
- Apple recommends replacing the battery if its capacity is below 80%.
- If you see a “Service” message, it means the battery needs to be replaced.
Look for Performance Management. This feature is turned on automatically if your phone has experienced sudden shutdowns due to a bad battery.
Check for signs of battery swelling.
- Is there any screen discoloration or is the screen lifting on one side?
- These are signs of a swollen battery.

If the battery shows any signs of damage, replace it immediately. Be careful when handling batteries, as damaged lithium-ion batteries can be dangerous.

3: Missing Sensor Data

Missing Sensor Data

Starting with the iPhone X, Apple introduced a sensor check system. Every 3 minutes, certain sensors must send a signal, or the phone will restart to protect itself.

If your phone turns on but restarts every three minutes, a missing sensor signal is likely the problem. Here’s what to do:

Check the logs (a place iPhone users rarely visit).
- Go to Settings > Privacy > Analytics and Improvements > Analytics Data.
- Look for files with names that include “panic” or “panic-full.”
- Find the panic string. Errors caused by missing sensors are usually labeled “thermalmonitord” or “watchdog timeout.” If you see different terms, try to look for clues in the text. You can also ask for help in the Answers forum.
Identify the missing sensor.
- For a “watchdog timeout” or “thermalmonitord” panic, look further down in the log to see which sensor is causing the issue.
Reseat the connectors of the indicated parts. Check them for damage. If needed, replace the part, but make sure you get it from a trusted source. Low-quality third-party replacements are common, so it’s better to spend a bit more for a good part.

Check and replace the faulty parts carefully.

Missing Sensor	Location	Likely Issue

PRS0 – Barometer

Charge Port Assembly

Charge Port Assembly or its connector on the Logic Board

Mic1 – Bottom Microphone

Power Button Cable, Camera Flash Cable

Power Button Cable, Camera Flash Cable, or their connector on the Logic Board

Mic2 – Rear Microphone

Power Button Cable, Camera Flash Cable

Power Button Cable, Camera Flash Cable, or their connector on the Logic Board

TG0V – Battery Sensors (for temperature and voltage)

Battery or its connector on the Logic Board

Battery, connector on Logic Board, Charge Port Assembly (iPhone 11 Pro/Pro Max), or board-level charging circuitry

TG0B

4: Faulty Peripheral

Almost every signal in an iPhone comes from or goes to the main board. If something interrupts this communication, it can cause the phone to shut down.

Here’s what you can try, but note that this method is more advanced and may need a full teardown of your phone. If this seems too difficult, it’s best to get help from a technician.

Boot with minimal hardware.
- Open the phone and disconnect everything except the display, battery, and charge port.
- Plug in a charger or USB cable to start the phone.
Reconnect parts one by one.
- If the phone works with just the basics, slowly reconnect each part.
- Pay extra attention to the home button and front-facing camera cables.
Replace the faulty part that causes the phone to shut down when reconnected.

5: Liquid Damage

Accidents happen, and your phone could end up in water. Even if it seems fine, just a tiny drop in the wrong spot can damage the internal circuits.

Here’s what to do if your phone might have gotten wet:

Check the liquid damage indicator.
- Remove the SIM tray and shine a flashlight inside.
- Look for the liquid contact sticker, which is under the display.
- If the sticker is red, it means it has touched liquid. If it’s white, the phone is dry.
A red sticker doesn’t always mean your phone is completely damaged, but it’s a sign to investigate further.
- Open the phone using a proper guide, and refer to the iPhone Liquid Damage Guide if needed.
Forget the “rice trick.” Leaving your phone in rice is a myth. It might help, but there are better ways to save your phone!

6: Logic Board

The logic board is the heart of your iPhone, controlling most of its functions. If none of the other solutions have worked, it’s possible that a part of the logic board is damaged.