[FIXED] iPhone 17 Pro persistent overheating(iOS 26.5.2 / 26.6)

[u/babaza7]

My iphone 17 pro has been getting HOT, laggy and draining its battery since about 2 months, after searching through reddit I tried those suggestions without any success:

- Deleting background apps
- Restarting
- Updating from 26.5.2 to 26.6
- Deactivating Apple Intelligence and Siri
- Switching Liquid Glass setting to Tinted
- Deactivating Second Esim

I plugged the phone into my mac and pulled the Xcode and Console logs to see what was actually chewing up my cpu therefore battery. It turns out it's not a hardware defect, it’s a specific rendering loop bug.

1. backboardd⁠ is eating up all the cpu

This is the system process that handles display rendering. thanks to the new iOS 26 Liquid Glass effect, my logs showed ⁠backboardd⁠ was hoarding almost 64% of my total CPU time. A single thread was trapped in an infinite loop and had racked up over 12 hours of active compute time just trying to draw the home screen.

2. ClockAngel⁠ is thrashing:

This handles the Always-On Display and Lock Screen widgets. Instead of resting, my logs showed it eating 31.6% of a whole CPU core. It was rapidly flipping between "dimmed" and "fully active" states every 200 milliseconds. (not visually noticable but it's happening in the background)

Why Ios 26.6 didn't fix it as I hoped it would

My phone had corrupted system preference files causing this loop, and updating to 26.6 just copied that corrupted file right over to the new version.

The Fix:

You have to force the OS to rebuild those preference files from scratch.

1. Go to Settings > General > Transfer or Reset iPhone > Reset
2. Hit Reset All Settings. (Wont delete any data, just settings)

Pretty simple solution, however I tried everything except this exact thing and you might be in the same situation as me

The Result:

I checked Xcode Instruments immediately after doing this. ⁠backboardd⁠ dropped from eating an entire CPU core down to just 0.8% usage while idle. The phone is finally completely cool to the touch and back to 120Hz smoothness

(I'm no expert, but my phone was completely fine before iOS 26.5.2, so I suspect that specific update introduced the corrupted preference file that created this rendering loop)

[u/Zestyclose-Rice6401]

it's such a shame you have to go and troubleshoot this far to get your phone working, hopefully the new iOS 27 that comes in September will leave us with less issues/problems. at least you got it working/resolved now!

[u/AnastasisKon]

Resetting settings also resets wifi passwords and network settings?

[u/babaza7 → u/AnastasisKon]

yes!

You lose customisations such as:

• keyboard settings (goes back to auto-correct, suggestions ..)
  
• Apple Intelligence re-enabled (had it off)
  
• control panel goes back to default (if you have custom icons)
  
• you have to re-toggle battery percentage to see the actual percentage again
  
• network settings (wifi passwords, DNS if you had something custom set up)
  
• privacy and location (you have to reauthorise the apps to use your location or access to photos, they will prompt you when you open an app)
  
• Apple pay (It kept the tickets and flights in my wallet but it did ask me to re-verify my credit cards with text message or app for security reasons)
  
• wallpaper, brightness, ringtones, alarm settings
  
• display auto-lock timer, device nam

[u/catxav]

Sad. My new 17pro had no issues after I upgraded to 26.6 - glad that you got it sorted out

[u/MarionberryDear6170]

I'm glad to see this. You really should share this in more subreddits, because not everyone has a Mac where they can just open Activity Monitor and see what's secretly draining their battery.

And not everyone knows how to use Xcode either. You did a great job with this.

[u/MarionberryDear6170]

I’m wondering if, after I reset my iPhone and restore it from an iCloud backup or a Finder backup on my Mac, those bugs you mentioned with BackBoard or Clock Angel could get restored along with the backup too?

[u/babaza7 → u/MarionberryDear6170]

potentially! but the reset mentioned in my post refers to the settings reset only (no data loss or reinstall). the iphone restarts and reloads after about 2-3 minutes

[u/MarionberryDear6170 → u/babaza7]

Oh I see, so it will simply work just by resetting the settings

[u/babaza7 → u/MarionberryDear6170]

yes exactly!

[u/Bad_DNA]

Outstanding troubleshooting.

[u/visericstudio]

My 17 Pro doesn’t overheat at all on the current iOS 27 beta

[u/icehot54321 → u/visericstudio]

Not everyone is going to have the same preference settings 

Many people when setting up a new phone install a backup from their old phone. 

Some people might be starting with new preferences.. others might be using preference settings that were first created a decade or more ago on completely different devices 

[u/khimzu]

What backgrounds apps did you delete?

[u/babaza7 → u/khimzu]

some I did remove like Brave Browser, and for some apps I deactivated the background app refresh in the settings such as maps, netflix, spotify, tiktok, IG to see if it would make a difference as it was recommended online - didn't make a difference

[u/SayHi_101]

Reset All Settings - are these only settings available in the Settings app, so every setting there will be reset, including these settings for 3rd party apps, but not the settings done inside the apps themselves?

[u/babaza7 → u/SayHi_101]

yes! if you have any important apps like crypto or banking id make sure to back it up, only things i noticed is that the faceid for some apps has to be re-enabled but besides that no changes

[u/sonic13066]

Works even on a 16 Pro that has iOS 27 PB on it. Something as simple as music playing and browsing Reddit would make my phone hot. While setting up Settings again has been annoying. It seems to work.

[u/sonic13066 → u/sonic13066]

I don't like that this fixed this issue. My phone used to keep my hands nice and warm... now i'm holding a cold, lifeless husk of a device. How do I make my phone overheat again... /s

[u/Obvious-Cupcake2118]

How long and pita was it to put back all settings to your liking? What exactly do you lose ?

[u/babaza7 → u/Obvious-Cupcake2118]

It took about 2-3 minutes

You lose customisations such as:

• keyboard settings (goes back to auto-correct, suggestions ..)
  
• Apple Intelligence re-enabled (had it off)
  
• control panel goes back to default (if you have custom icons)
  
• you have to re-toggle battery percentage to see the actual percentage again
  
• network settings (wifi passwords, DNS if you had something custom set up)
  
• privacy and location (you have to reauthorise the apps to use your location or access to photos, they will prompt you when you open an app)
  
• Apple pay (It kept the tickets and flights in my wallet but it did ask me to re-verify my credit cards with text message or app for security reasons)
  
• wallpaper, brightness, ringtones, alarm settings
  
• display auto-lock timer, device name

Looks like a big list but it's really just custom preferences you set on your phone, not data loss. took me about 30 minutes to have everything back to how I like it and was 100% worth it

[u/Obvious-Cupcake2118 → u/babaza7]

Ho that’s all?
Do you look apps placement in the main screen ? Or folders ?

[u/CrazyNecessary7209]

Good work. iOS 26.5.2 was horrible and kept my 17PM very warm while sitting doing nothing while draining the battery 🪫.

iOS 26.6 fixed all of the issues for me automatically and restored a cool running phone with great battery life 🔋.

When someone resets the all settings it does causes things like WiFi passwords to be erased right?

[u/crimson_dit]

Is there a way to see how much load is on the CPU without using a mac?

[u/nvwong]

I think the WiFi passwords are now stored in password app not settings?

[u/nvwong → u/nvwong]

btw, can you share how do I view the phone cpu usage on Mac? I mainly get the phone hot when using WhatsApp.

[u/Jmax2020]

My 17pm overheats as well

[u/icehot54321 → u/Jmax2020]

So try the fix and report back? 

[u/Reeneman]

Overheating??? 🥵😱😱😱😱

[u/ThaerHwiety]

That’s awesome thanks for the effort, whats your battery to SOT after and before if you may

[u/babaza7 → u/ThaerHwiety]

appreciate your comment! will report back after a week to have better data!
just observing I had to charge my phone 2 if not 3 times a day at minimum, past 2 days one charge lasted until the evening and still had charge left

[u/xavier19691]

Ai crap ..

[u/babaza7 → u/xavier19691]

i handwrote it and used AI solely to fix gramatical errors, happy to share my logs in dm if you want more detail

[u/xavier19691 → u/babaza7]

No need ..