iPhone 15 Plus — sensor array 0xa1: Battery

High confidenceVerified sourceSMC: silent sensor

On the iPhone 15 Plus, 0xa1 means: Battery (fuel gauge data).

What does this code mean?

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.

Which part to test first?

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.

The same code on other models

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Sources