0xa1 — SMC: silent sensor
SMC “BSC failure” panic: the system management controller (built into the SoC) periodically waits for a response from each mandatory sensor; here, the battery data is no longer coming through (0xa1 designates the battery on this model, it is not a single bit). With no response, it forces a restart, which repeats roughly every 3 minutes (≈180 s) as long as the sensor stays silent.
On iPhone 15 Plus, iPhone 15
Battery (fuel gauge data)
SMC “BSC failure” panic: the system management controller (built into the SoC) periodically waits for a response from each mandatory sensor; here, the battery data is no longer coming through (0xa1 designates the battery on this model, it is not a single bit). With no response, it forces a restart, which repeats roughly every 3 minutes (≈180 s) as long as the sensor stays silent.
First check
Check whether the battery percentage is displayed (a reading stuck at 0–1% reveals lost battery data), inspect the battery connector (bent pins), test with a known-good battery, then measure the connector's data lines in diode mode.
On iPhone 15 Pro Max, iPhone 15 Pro
Battery (fuel gauge data)
SMC “BSC failure” panic: the system management controller (built into the SoC) periodically waits for a response from each mandatory sensor; here, the battery data is no longer coming through (0xa1 designates the battery on this model). With no response, it forces a restart, which repeats roughly every 3 minutes (≈180 s) as long as the sensor stays silent.
First check
Check whether the battery percentage is displayed (a reading stuck at 0–1% reveals lost battery data), inspect the battery connector (bent pins), test with a known-good battery, then measure the connector's data lines in diode mode.