iPhone 18 Pro — sensor array 0xa9: Battery

Low confidenceVerified sourceSMC: silent sensor

On the iPhone 18 Pro, 0xa9 means: Battery (TB0T sensor: temperature not reported).

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 and forces a restart as long as a sensor stays silent. Here the log itself names the failing sensor: TB0T, the SMC key for battery temperature, with the value 169 (0xa9). No public source documents this code on the iPhone 18 Pro yet: the battery mapping comes from the sensor name and from earlier generations, where the same value 169 / 0xa9 points to battery data (Repair Wiki, iPhone 16 Pro) and where TB0T is linked to the battery (iFixit 936588 on a 14 Pro Max; iFixit 943079 on a 15 Pro, battery replaced = fixed).

Which part to test first?

Model released in September 2026: check Apple warranty coverage first, before opening the phone.

The same code on other models

Field cases

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Sources