I have an iPhone 13 Pro running iOS 15.6, which I got in January. Every now and then it will do a very specific, distinct pattern of four vibration pulses that lasts around two seconds, and which feels like it's the hardware trying to notify me of something specific.

There are no indicators on the screen and no other notifications that go out (either on the phone or on my Apple Watch). Often it happens when I physically sit down in a chair, but sometimes it happens when I've just been sitting. It doesn't seem to have any correlation to activity from other devices nearby. Because there's no other sound I have no idea if it happens without the phone being in my pocket.

I have tried holding the buttons in all possible combinations and none of them cause this specific vibration pattern to occur; the "emergency/SOS" vibration is the closest thing but its vibration pattern is totally different (being a couple of brief clicks), and is accompanied by other effects (such as FaceID shutting off and a bunch of UX for contacting emergency services popping up).

It's always exactly four pulses (bzzz bzzz bzzz bzzz), and it seems like the sort of thing that would be a specific diagnostic code from the phone.

I have contacted Apple support about this and they have no idea.

It generally happens once or twice a day, at totally random times. The phone is always locked and when I unlock it, it goes straight to the application launcher/home screen. It seems unlikely to be a notification coming from an app, and I've disabled push notifications on pretty much every app anyway.

Does anyone have any idea what's going on?

  • This exact issue happens for me too on an iPhone XS. Four vibrations in a row, randomly throughout the day. One theory is that perhaps my cellular provider is pushing some kind of silent SIM card update, but I have nothing to support that theory. Hoping eventually we find an answer. Commented Nov 28, 2022 at 16:28
  • I'm glad it isn't just me! Although it hasn't happened in a while for me now.
    – fluffy
    Commented Nov 29, 2022 at 17:29
  • It just happened to me again even with System Haptics turned off. Commented Nov 30, 2022 at 18:09
  • 1
    @OranDennison omg I have that app too, that might be it! I haven't had the vibration thing happen in a while and I think I was using that device heavily back when this issue was occurring! Gosh, how did you ever track that down?
    – fluffy
    Commented Nov 3, 2023 at 23:04
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    I reached out to support, and they suggested turning off the Offline Reminder in the device settings. This also seems to have fixed the issue. Commented Nov 15, 2023 at 16:28

1 Answer 1


Check Settings > Sound & Haptics to see if there are any vibration-only haptics set. One potential culprit is the New Mail haptic.

  • Good idea, but unfortunately that's not the issue. None of my configured alerts have the four-pulses behavior, and all of my configured alerts are things I've accounted for. I do have "system haptics" enabled, but whatever I'm being alerted for isn't very effective since I can't figure out what it is.
    – fluffy
    Commented Aug 10, 2022 at 18:34

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