iPhone screen dims randomly

I have the same issue. Mine is always when the phone us under heavier load, like playing a game. It's worse when it's on the charger. It doesn't just dim once, like my iPhone 7+ did. It dims in stages, going from 100% to like 50% or lower in 2 or 3 steps. I am convinced it is a heat/safety feature, or bug. It's **** annoying.

You are correct Apple added this feature to prevent yo from getting heat damage. There are lots of things in your phone that can easily be broken by high temperatures such as the glue holding you’r screen to you’r phone.

I have the same issue. It also happens on my 10.5 iPad Pro. Have tried all the suggestions in this growing thread. It’s a real problem as both my devices are fine and readable in the sun and then they “auto, auto dim” making them barely readable in sunlight. Safe to say it is definitely not a settings issue as also noted by others and appears to be a software driven issue as it’s happening across multiple device types. It also remains despite numerous IOS updates (currently 11.4.1). Sure looks like it’s design intentional to reduce heat. What I don’t understand is why Apple isn’t acknowledging this. This is clearly costing them in terms of needless hardware replacements and customer satisfaction. Apple?

When I use my iPhone X as a screen for my drone. This happens every time. I also assume it’s from heat (I live in Florida) I’m curious on how many of us use a case that might be holding in some heat. Let’s try our specific issues without and see if it helps some ???

This isn't auto brightness I can assure you! This is a sudden drop in screen brightness when the phone heats up, ALL Brightness Settings have been turned off. It has nothing to do with settings, it's just a hardware issue with the CPU or rather the GPU inside of that. I guess it goes into low power mode to not melt when the CPU is under load.... Bad Engineering if you ask me! They should've separated the two to avoid this rather than putting everything on one chip.....

I contacted Apple support via chat today. They told me I need to go to the store and have the Genius Bar look at it.

I think it's a combination of too much heat (call it a hardware bug) and a feature to avoid overheating. My second iPhone X still dims, but for much shorter periods of time and not as much.

Same issue here. Mine only occurs if I am using it as GPS running Waze. It starts off nice and bright and after an undetermined amount of time the screen looks like it is about 1/4 of the way bright. When I check the brightness toggle it is all the way up.

If I turn the phone off then back on it resolves it. The phone does seem somewhat warm.

As others stated it’s likely a heat issue which stinks because my old iPhones never had the issue. Only noticed it after I got the X.

This is not an Attention Aware issue. Yesterday my phone was dimming on its own yet again while outside and I was standing next to my partner who’s phone was not dimming. We have identical settings regarding Attention Aware and we both have any potential auto dimming turned off. My screen, even at its brightest, isn’t crisp and white like his. Additionally, the phone will freeze for no apparent reason so I took my iPhone X into the Apple Store and they ran a diagnostic test and found nothing wrong, yet there most definitely is something wrong. It was a huge waste of time and quite frustrating considering the price of this phone.

I have been to the Apple store and had my iPhone 10 replaced twice now. The first iPhone was backed up from my original phone. The phone still dimmed on its own. The second one I did not back up But ran as new device . This phone continues to DM outside and inside while plugged in. There is obviously a defect in the iPhone X screen that Apple either refuses to admit or could possibly be working on it.

I’ve been to the Apple store twice now. They gave me a brand new iPhone X the first time but backed it up from my old phone. The problem continued. I returned to receive yet another new iPhone X, but ran this one as a new device and did not back it up. This phone continues to dim While outside and will also dim when inside and plugged in. I believe this is a heat related issue.

I dont know about anyone else but I checked my Display Accommodations early on as did Apple Genius'. All the settings you mention have never been enabled therefore didn't need to be turned off. The problem with the screen dimming is not caused by settings. At least not in my case. I think it might have to do with low battery, heat or perhaps an app(s) doing something within the phone that is exhausting it. I have a lot of apps on my phone so I wonder if an app(s) (although the screen dims even when I might only have one app open) is/are not working properly with the OS. The other thing my phone does as I mentioned earlier, is close the imessage app mid-typing and open another app, randomly. Im a fast typer (not that that should be a factor) but it seems to happen when I type quickly.

I cannot tell you how glad I am to have found this thread. I’ve been dealing with this issue since the iPhone 5. I’ve always found my screen dims when using a GPS app of some sort - it doesn’t really matter which one; Waze, Apple or Google Maps, they all suffer from the same issue. Very frustrating attempting to look at directions on your phone in a city you’ve never driven in on a bright day when this happens. Considering the amount of folks posting about this and the fact this is a potential safety issue, I’d expect Apple to jump on a fix. I mean, wouldn’t their engineers experience this too if they use iPhones?

I asked my advisor about this on my call today and she said that I need to take it to the Apple store and have them run diagnostics. So this is obviously a hardware issue that can’t be fixed by an update. Sounds like we are going to have to wait for the iPhone X+ or iPhone XX or whatever the new is going to be called and hope they fix the overheating issue

I first noticed this issue when with my new iPhone 8 back in November. At the time, the folks at the Apple Store made me run lots of tests including restoring from backup, then installing new OS. They eventually gave me a new replacement phone. I have since given my wife the iPhone 8 and picked up a new iPhone X. I have had the same intermittent dimming issues with the iPhone X. I have tried all the settings folks recommend on this thread. Last week, the folks at the Apple Store replaced my iPhone X with a new one. They didn't even ask this time as I think they are well aware of the issue. I did ask the technician if he knew about a widespread problem. He said he had only seen the issue once before -- hmmm.

I play a lot of Pokemon Go which does use GPS and often I notice the phone warm. The problem isn't related to low charge and doesn't go away if I connect to external battery to charge. I often have to restart the phone, but that doesn't always do the trick.

I don't necessary think this is a hardware issue as others have speculated since it happens on more than just the iPhone X if you've read through this whole thread. I think this is an iOS 11 issue related with the auto-brightness setting being overridden by some environmental factor. Maybe the ambient light sensor is getting confused, but if auto-brightness is turned off, it should not matter.