So why is the iPhone randomly restarting

Random restart on iPhones can be caused by many things. Considering that we repair iPhones every day, we have outlined most common causes of random restarts below. The information provided below is based on diagnosis and should not be considered as the ultimate guide or solution for all random restart issues in  all  iPhone models.

Below are the common faults that might cause your iPhone to randomly restart (auto reboot).

1. A faulty proximity flex cable

Its common for the newer iPhone models to randomly start restarting for no reason. Although the user might think that the phone just restarted for no reason, an experienced technician may have something else to say.

NOTE:  Inorder for a technician to have a higher success rate on repairing a rondomly rebooting iPhone, its advisable not to restore or update the iPhones operating system (software) as there is what is called a panic log in the iPhone’s settings(Settings-> Privacy-> Analytics & Improvements-> Analytics Data-> Scroll down to the files starting with “panic-full) which makes repair technicians able to easily pin point the cause of the problem by analyzing the panic log.



iPhone's proximity sensor flex cable (ear speaker cable)
An example of a panic log in iPhones
An example of a panic log in iPhones

A faulty priximity cable might cause the iPhone to either restart every 3 minutes or to boot loop. Water or liquid may cause the microscopic components on the ear speaker ( Proximity cable) to short out causing the iPhone to auto reboot(boot loop) sometimes making the Iphone unable to fully power on (boot into the operating system).


A client came to us with an iPhone X  was randomly restarting unable to boot into the operating stystem. Upon arrival our technician told the client that there is a high posibility that the device is auto restarting due to a water damaged proximity cable to which the client said there was no history of any water or liquid damage to his iPhone X. Upon examination under the microscope, the technician found that the auto restart on the iPhone X is indeed being caused by water damage which was severe around the proximity sensor. We told  the client exactly what we found out and he admitted that every night he uses to clean his iPhone’s screen with water before he goes to bed. We fixed the device’s proximity sensor and the iPhone X was able to boot into the operating system.


For the iPhone’s faceID functionality to work, a normal original proximity sensor cable is required. Repairing a water damaged proximity flex cable requires special skills and  expensive equipment like a microscope therefore such repairs should not be attempted by a random personell. Replacing the ear speaker ( proximity sensor cable withought not what one is doing) will forever disable the faceID functionality on the iPhone

2. A faulty charging flex

The Apple iPhone’s charging flex cable might seem simple but contains or is connected to alot of important components like mics and so on. The newer iPhone models have a way of knowing (sensors) if some of the essential components  are faulty or damaged. Once the iPhone detects faulty parts on the charging flex cable, it tries to alert the user that something is not okay by triggering itself to randomly restart (sometimes every 3 minutes) and leaves a log in the settings (Settings-> Privacy-> Analytics & Improvements-> Analytics Data-> Scroll down to the files starting with “panic-full) that can be interpreted by a trained technician

iPhone 15 charging port flex cable

Non OEM charging port flex cables can cause the Iphone to restart randomly(usually every 3 minutes)

3. A faulty power button

A faulty iPhones power button may cause the iPhone to auto reboot or boot loop

4. Motherboard issue

As can be seen in the image below, all the newer iPhones (starting from iPhone X) have what technicians like to call a sandwich motherboard. If subjected to a hard fall or pressure ( as you sit in the car while the phone is in your pocket), the solder joints that hold the two layers together tend to break causing sudo soldering therefore making the phone malfunction. 

This might cause the phone to randomly restart or boot loop

iPhone Xs Motherboard


A client came to Apple Repair South Africa with an iPhone X that was dead due to water damage. Upon inspection, the iPhone was found to be stuck in DFU mode. As part of the diagnosis, we disconnected the power and vlume button cables from the iPhone’s motherboard but the iPhone was still stuck in DFU mode. We tried updating and restoring the iPhone. The flashing proccess was completed successfully but the device was first getting stuck into recovery and if restarted it would go back to DFU mode.

We did split the sandwich motherboard and found that water had affected parts of the lower board. We replaced the damaged parts , rejoined the sandwich boards and  wollah!!!! The device turned on and was able to boot into the operating system. Another happy custommer.

Repairing the motherboards of the newer iPhone models require very rare set of skills and expensive equipment. If attempted by a random John, the iPhone may be rendered completely useless.

5. A break in communication between the CPU and the charging port lines

This  is a factory fault common on iPhone SE 2020 models. What causes  this fault is a break  of traces within the motherboard  ( communication lines I2C1_AP_SCL and I2C1_AP_SDA)

These two data lines are responsible for the communication between the CPU and the charging port flex. If these lines  are broken, the iPhone’s sensors in the operating system are unable to detect things like the mic which triggers the iPhone to automatically restart every 3 minutes. An experienced technician can be able to understand the cause of the auto restart by going into the iPhone’s  settings (Settings-> Privacy-> Analytics & Improvements-> Analytics Data-> Scroll down to the files starting with “panic-full) read and understand the code or analyze the log using the panic log analyzing software.


A client drove from Sandton (Gauteng) to Bethlehem (Free State)  in order to get her data recevered from her iPhone SE2020 which would restart every 3 minutes.

Upon inspection, we found that her iPhone had a broken internal communication traces between the CPU and the charging port connector. We did rebuldthe damaged traces and the device was able to turn on and boot into the operating system without randomly restarting again. Below is a reviw she left us

“Massive thank you to Titus for fixing my iPhone. The touch screen stopped working and the phone was restarting every 3 minutes. Nobody in Johannesburg was able to fix the device without resetting it, which was a problem because I wanted the pictures. I ended up driving through to Bethlehem from Johannesburg for the repair. Titus was able to fix the device in 2 hours. In future, I will happily courier all broken devices to Titus for repair (the CourierGuy is directly next door to the store). Thank you Titus for your expertise and fantastic service!” Review link

iPhone SE 2020 Panic Log

6. Poor Battery Communication

Some batteries just require to have the + and – terminals. However iPhone batteries are not like that. iPhone batteries have data lines that help the iPhone tell what percentage is the battery on, what is batteries’ temperature, is the battery charging or discharging? If  for some reason the iPhone’s battery data lines are not making a good connection or are damaged, the sensors in the  iPhone’s software will be unable to access such data therefore will trigger the iPhone to automatically restart as a way of alerting the user that something is wrong.

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