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iPhone 15 overheating? Here's what to know and do

Some early adopters of the iPhone 15 are reporting that the handset can become too hot to hold.
Written by Adrian Kingsley-Hughes, Senior Contributing Editor
iPhone 15 optimized charging
June Wan/ZDNET

Some iPhone 15 early adopters are turning to social media to report overheating issues that can drive the temperature of the handset to over 100°F, making it uncomfortable to handle.

Review: iPhone 15 Pro: Coming from iPhone 12 Pro or earlier? This upgrade will wow you 

UPDATE: Apple confirms iOS 17 and app bugs are causing overheating, not a hardware issue, and releases iOS 17.0.3, an update that "addresses an issue that may cause iPhone to run warmer than expected.".

So, what's happening?

9to5Mac's Ian Zelbo posted on X that his iPhone 15 Pro Max became "almost too hot to touch" while fast charging.

Tech reviewer Mohit Verma posted a video on X showing his iPhone hitting 42°C (107°F) after "just a 2-minute FaceTime call or when scrolling through reels for 8-10 minutes."

Alex Gear & Tech also posted a similar video.

Here is thermal imaging comparing the iPhone 15 Pro Max and the Samsung Galaxy S23 Ultra. This suggests that the iPhone's lack of active cooling is concentrating the heat in a specific spot.

Then there's chip performance throttling. This test suggests that in two minutes of heavy loading, the iPhone lost 25% of its performance. This would point to a thermal management issue.

The common thread in many of these reports seems to be USB-C charging. Maybe there's a bug here that surfaces under certain conditions or with certain charging hardware. 

Another option is that the titanium chassis is more effective at dissipating the heat, and this in turn causes the handset to feel hot. But aluminum and stainless steel are also good conductors of heat, so I doubt that the material is the issue.

ZDNET has not come across this issue in our testing but there's no doubt that these measured temperatures are abnormally high.

Also: iPhone overheating? Here are 8 potential causes and their solutions

Note that while 42°C/107°F is hot, it's within the safe "no injury" temperature range. In fact, ASTM C1055 (the Standard Guide for Heated System Surface Conditions that Produce Contact Burn Injuries) states that the average person can touch objects up to 60°C/140°F for up to five seconds without sustaining irreversible burn injuries.

Anything that seems to trigger it?

I've seen a few different theories. 

First theory is a rogue app. Faruk Korkmaz of the YouTube channel iPhonedo puts the problem down to the Instagram app, and he's done tests to show just how quickly the iPhone overheats when this app is running on his hardware. 

Another theory is that it is related to fast charging, with Android Authority noting that the overheating happens when using a 65W USB PD GaN charger, but goes away when using a 15W USB PD charger, but that charging time is significantly longer.

I've seen a lot being made of the fact that thermal imaging shows this heat to be concentrated around the location of the iPhone's mainboard, which would suggest that the heat coming from the A17 Pro chip. That said, thermal imaging of devices through the case can be hard to interpret because the location where the heat is being dissipated might not be the location where it is generated.

Is this a bug?

History shows that both new iPhones and new iOS releases are prone to bugs that are fixed by subsequent iOS updates.

While it's easy to point the finger at charging (but remember, all smartphones get warmer when charging -- that's just physics), the throttling of the chip points more to a thermal management issue. Apple is either dealing with a software bug or needs to improve the way the iPhone operates when running heavy workloads. 

This could also be something specific to certain handsets or a configurational issue resulting in an abnormally high level of background activity, such as machine learning or indexing.

How do I check my iPhone for overheating?

The first way is touch. Does it feel hot? 

If you want to get more specific, you could use an infrared thermometer or a thermal camera.

How will my overheating iPhone be fixed?

This issue is likely a software issue, and will be fixed by a future software update from Apple or an app update. 

My iPhone is overheating! What should I do?

The fastest way to cool down an iPhone is to turn it off completely and let it come down to normal temperature naturally. Don't try to speed up the process by putting the iPhone into a refrigerator or ice box as this could also damage the battery.

Also: Why iPhone 15 isn't as repairable as Apple wants you to believe

As for your options as to how to prevent this, download and install iOS 17.0.3. Hopefully, that will address this issue and allow you to enjoy your new iPhone.

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