Guide
A restart every few minutes is a symptom
Shops see iPhones that boot and then restart, often around three minutes. The clock is not a part number.
Why three minutes shows up in the log
A userspace watchdog often gives a process 180 seconds to check in. 180 seconds is three minutes. The line can look like a missed check-in from a named process.
That sentence names a missed check-in. It does not name a flex, a battery, or a board.
SYNTHETIC example, not a customer log
panic(cpu 0 caller 0x0): userspace watchdog timeout: no successful checkins from thermalmonitord in 180 seconds
Read the panic string before you order
The next lines pick the path. A missing-sensor list names a sensor. SMC PANIC or SMC ASSERT with a sensor array is an SMC case. A watchdog with no missing sensor is a different case.
Log's thermalmonitord rule treats a watchdog with no missing sensor as a software-leaning result. A three-minute loop can be any of these shapes. The interval alone is not enough to order a part.
The model still changes the answer
Log's model-aware SMC suggestions cover the iPhone 13, 14, 15, and 16 families in the rule table. The same symptom on another model can point at a different row, or at no row.
Confirm the product string in the log before you reuse a part name from a different phone. If the result is low confidence or names no part, the log did not earn a stronger claim.