0x4000 — 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 data link with the battery is lost. With no response, it forces a restart, which repeats roughly every 3 minutes (≈180 s) as long as the sensor stays silent.
On iPhone 13 Pro Max, iPhone 13 Pro, iPhone 13 mini, iPhone 13
Battery (data lines / fuel gauge)
Medium confidenceVerified sourceSMC: silent sensor
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.
iPhone 13 Pro Max ›iPhone 13 Pro ›iPhone 13 mini ›iPhone 13 ›