iPhone SMC Panic Assert

If you've dug into the panic logs on your iPhone and found an "SMC Panic Assertion Failed" error, you're not alone. It appears commonly and started cropping up in iPhone 13 and later models

The SMC, or System Management controller will be familiar to those who have ever done any troubleshooting on a MacBook. iPhones also include an SMC, but rather than being its own chip, it is part of the CPU.

The error is generated when the SMC fails to receive expected communication from a specific sensor. When it doesn't get this data, it reboots the device. If it isn't resolved on reboot, your phone will keep rebooting, every three minutes (180 seconds). This can be resolved by restoring communication, usually by replacing the part where the sensor is housed.

Once you locate the panic, skim to find where it mentions a specific "sensor array." A few sets of characters will follow and then the actual value for the sensor at fault. It will begin with "0x" followed by several other numbers. Use the table below to locate your problematic sensor and replace the affiliated part.

Note that later model iPhones have started presenting the sensor code in decimal values rather than hexadecimal.

*Replacing the front sensor assembly will disable True Tone and auto brightness functionality, even when using an original Apple screen. Face ID is also disabled, unless the iPhone is running iOS 15.2 or newer.

**Replacing the battery will result in a warning message that the battery installed is not an OEM Apple battery, unless you use an Apple battery supplied by Apple's Self Service Repair program and run System Configuration.

***There is a sensor on the wireless charge coil cable that is paired/calibrated to the device. Replacing it with another back glass assembly, or wireless charge coil will result in the same issue, unless you use an Apple part (back glass) supplied by Apple's Self Service Repair program and run System Configuration.

Note that as of the release of iOS 18, a new feature called the Repair Assistant is available. The Repair Assistant is capable of pairing those serialized parts to the logic board, thus eliminating the genuine parts warnings and restoring any lost functionality. As of this writing, the Repair Assistant will only work with genuine Apple parts, which can be either new or used. Be aware that the used parts may not be taken from a phone that is reported lost or stolen; the Repair Assistant will refuse to pair them if that's the case.

More than one sensor can be indicated; for instance a code of 0x1800 on an iPhone 13 would indicate sensor problems on both the charge port and the front sensor cable.

• These numbers are in hexadecimal so normal addition like you might be thinking won't work. For example, 0xC0000 would mean both the charging port and the front sensor assembly on an iPhone 14 are affected. Use a programmer's calculator, set it to hexadecimal and add 0x40000 + 0x80000 = 0xC0000.

If replacing the part did not resolve the issue, the logic board may be at fault, especially if the device is liquid damaged.

• Inspect the connector. Magnification will help. The pins are tiny and damage may be difficult to notice with the naked eye.
• You can get more information by using a multimeter and checking the diode mode readings on the related board connector. It can confirm a board level issue, or help to find the cause if you're versed in troubleshootingcircuit boards.

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