iPhone 8 — tp1a: Thermistor
Medium confidenceVerified sourceMissing sensor
On the iPhone 8, tp1a means: Thermistor (NTC) on the logic board: FOREHEAD_NTC line shorted to ground (capacitor / resistor).
What does this code mean?
Watchdog panic: thermalmonitord no longer receives the reading from TP1A, a temperature probe (NTC thermistor) soldered onto the logic board, not a replaceable part; with no response for ~3 minutes, iOS restarts the iPhone. On an iPhone 8 with this panic, a technician found the FOREHEAD_NTC line shorted to ground and fixed it by replacing the capacitor and the resistor.
Which part to test first?
Measure the FOREHEAD_NTC line (short to ground); replace the capacitor and the resistor of the thermistor concerned.
The same code on other models
- iPhone XThermistor on the logic board
- iPhone SE (1st generation)Rear camera thermistor on the logic board
Field cases
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