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iPhone 15 overheating fix: Thermal imaging shows before and after iOS 17.0.3

The iPhone 15 overheating problem was both confirmed and visualized using thermal imaging, and now the same tech has been used to show the impact of Apple’s software fix.

In our own poll, a full 57% of 9to5Mac readers with iPhone 15 models had experienced the overheating problem …

iPhone 15 overheating

We first started seeing widespread reports of the issue not long after people received their new iPhones. Some users, including our own Ian Zelbo, found that their phones were almost too hot to hold in same circumstances.

My iPhone 15 Pro Max is almost too hot to touch while fast charging right now. I thought people were exaggerating, but no, this isn’t great.

In our own poll, a total of 57% of readers with iPhone 15 models had experienced the issue:

  • During charging: 19%
  • During demanding use: 11%
  • During normal use: 27%

Apple’s fix

Apple confirmed the problem, but denied reports that it had anything to do with Pro model chassis change from stainless steel to titanium. Indeed, said the company, the latest models actually have better heat dissipation than previous iPhones.

The iPhone maker told us that it was instead a mixture of a bug in iOS 17, and problems with apps like Instagram and Uber, which were hammering the phone enough to drive up temperatures.

Apple issued a fix in iOS 17.0.3.

This update provides important bug fixes, security updates, and addresses an issue that may cause iPhone to run warmer than expected

Some had worried that the company may have throttled the performance of the A17 Pro chip in order to achieve this, but benchtest results showed no sign of this.

Before and after thermal images

Objective data for the issue was provided using a Forward-Looking InfraRed (FLIR) camera, also known as a thermal imaging camera. This not only provided a visual representation of the heat, but also showed the specific temperatures measured – which were significantly higher than those measured with competing phones.

ZDNet used the same kit to take temperature readings before and after installing iOS 17.0.3. This confirmed that the update did indeed resolve the issue.

Before:

I used a thermal camera to measure the heat and found that the iPhone 15 Pro Max got as hot as 107.1 degrees Fahrenheit. This was much hotter than other iPhone and Android phones, which typically maxed out at 85 to 95 degrees when fast-charging in my tests. The hottest any other phone got when testing in the same conditions was the Samsung Galaxy Fold 5, which got up to 98.7 degrees Fahrenheit.

After:

I downloaded the iOS 17.0.3 update and allowed my iPhone 15 Pro and iPhone 15 Pro Max testing units to drain their power and then plugged them in for fast-charging using the same parameters and the same equipment in the same location as my earlier tests. This time they never got more than slightly warm to the touch, and they didn’t get above 93.8 degrees Fahrenheit. They stayed between the high 80s and low 90s — a big improvement from before iOS 17.0.3 when the two iPhone 15 Pro models were consistently above 100 degrees Fahrenheit when fast-charging with the 35W charger.

You can see the visual results in the photos above.

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Avatar for Ben Lovejoy Ben Lovejoy

Ben Lovejoy is a British technology writer and EU Editor for 9to5Mac. He’s known for his op-eds and diary pieces, exploring his experience of Apple products over time, for a more rounded review. He also writes fiction, with two technothriller novels, a couple of SF shorts and a rom-com!


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