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iPhone 4 ambient light sensor problem or software bug?

6286 Views 14 Replies Latest reply: Aug 23, 2013 10:20 AM by Joey!! 【ツ】 RSS
Joey!! 【ツ】 Level 2 Level 2 (255 points)
Currently Being Moderated
May 13, 2011 4:01 PM

First things first:

I purchased my iPhone 4 from AT&T last September.

I am running iOS 4.3.3.

I do not have a case that would cover or affect the sensor (just a bumper case).

I have auto-brightness enabled with the scrubby located in the middle of the bar.


When I wake the iPhone from sleep, it is at half brightness until I slide to unlock, then it auto adjusts either brighter or dimmer to the correct brightness level. It works just as expected with no problems.

Then I take the phone into a brighter area and the screen is adjusted to be brighter, again working just as expected.

But if I take it into a dark room, the screen does not get dimmer. If I want the brightness decreased, I have to put it into sleep mode and then wake it up and slide to unlock before it will adjust to the correct brightness level.


Is this a problem with my ambient light sensor or simply a software bug? Or is it supposed to work that way?


Thank you!

iPhone 4
  • John Hammer1 Level 4 Level 4 (2,805 points)

    That's how mine works, too. I'm pretty sure that's "working as intended" but I do agree it would be better if the screen would dim while active if moved from a brighter to less bright environment.

  • sachit Level 1 Level 1 (0 points)

    Same here.

  • sachit Level 1 Level 1 (0 points)

    1) Adjust the brightness to any level ( with Autobrightness ON ).


    2) Take it to any light environment ( bright or dim )


    3) Off the autobrightness ( brightness level should be same ) ) . As soon as u off it, u will c the changes in the brightness.


    Thats the way i checked whether its woking or not.

  • apolo313 Level 1 Level 1 (0 points)

    I have the same problem with my iPhone 4; however, I'm sure that this is not the way it is supposed to work. My brother has an iPod touch 4g and the auto-brightness feature works just fine on it, it both brightens and dims automatically without putting the device to sleep, and I notice the change in brightness while walking from a bright place to a dark place and the otherway around. So if it is working this way on iPod touch 4g, why not on iPhone 4????

  • apolo313 Level 1 Level 1 (0 points)

    That's right, it really shows that the auto brightness is working and you really notice the change, but it doesn't prove that the feature is working properly since the device doesn't dim when you go to a dark ambient.The change that you notice is because the brightness that you manually set is higher than what you needed in the bright ambient, so when you turn the auto brightness off the brightness goes to the manually set state, and when you turn it on it goes to the state that it's supposed to be in the bright place not the state that it should be on the dark place. The brightness that you need in the dark ambient is the brightness that you get when you wake your device from sleep in a dark ambient, and you will never get that same brightness when you move from a bright ambient to a dark ambient, and that's the problem.

  • sherri-lyn Level 1 Level 1 (0 points)

    Hi guys, my ambient sensor is not working at all. Go from light to dark rooms and vice versa and no change, auto brightness ON or OFF still no plan. Surely this has got to be a BUG.

  • Morpheousman Level 1 Level 1 (0 points)

    Your iPhone's ambient light sensor is functioning normaly.


    Found this in another forum...


    Camouflaged behind the black glass where you can't see them except with a bright flashlight are two more sensors: a proximity sensor that shuts off the screen illumination and touch sensitivity when the phone is against your head (it works only in the Phone application), and an ambient-light sensor that brightens the display when you're in sunlight and dims it in darker places.


    Apple says that it experimented with having the light sensor active all the time, but it was weird to have the screen get brighter and darker all the time. So the sensor now samples the ambient light, and adjusts the brightness; it does this only once--each time you unlock the phone after waking it.


    You can use that tip to your advantage. By covering up the sensor (just above the earpiece) as you unlock the phone, you force it to a low-power, dim screen-brightness setting (because the phone believes that it's in a dark room). Or by holding it up to a light as you wake it, you get full brightness. In both cases, you've saved all the taps and navigation it would have taken you to find the manual brightness slider in Settings.



  • ShubSharma Level 1 Level 1 (0 points)

    Guys if you have too this problem with your iphone light sensor that its light is not getting dim in low light situations then follow these steps:

    1) Calibirate your light sensor.

    or 2) Reset your device.

    or 3) Restore your device iOS with the help of itunes but this will delete your all data including purcased apps.

    If all these don't work for you take your device to apple's service centre.


    And guys I want to tell you one very important thing that if your light sensor is not responding to low light situations that means your light sensor is malfunctioning it should respond automatically to both the light situation bright and dark with "auto brightness on" And I found this by chating with the technical advisor of apple support service.


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