Why does my iPhone keep turning off and on after 3 minutes?

If it is not an Auto Lock setting......there is a hardware problem with the battery and/or the main circuit board on the iPhone.

Make an appointment at the Apple Store / Genius Bar or take the phone to an authorized Apple service shop to let them check, test and provide you with an estimate of repair cost.

You can find a list of authorized shops in your area using this link:

Find Locations

Do you by chance have your iPhone’s Auto-Lock set to 3 Minutes? You can check and change in Settings > Display and Brightness > Auto-Lock.

"Why does my iPhone keep turning off and on after 3 minutes?: When I'm using my phone it switched off and on it self after 3 minutes"

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Have you just updated your iPhone? If so, try this following...

Fixing a Boot Loop:

Your iPhone can't times be in a Boot Loop. This typically occurs when you go about installing an update, and it stalled while in the process. So, see if this fixess this. Use my User Tip: How to Fix an iPhone in a Boot Loop - User Tip