iPhone 12 — tp3r: Logic board

Low confidenceVerified sourceMissing sensor

On the iPhone 12, tp3r means: Logic board (TP3R temperature probe, exact part not identified) — after ruling out battery / charging port.

What does this code mean?

Watchdog panic: thermalmonitord no longer receives the TP3R reading and stops checking in; with no response for about 3 minutes, iOS restarts the iPhone. TP3R is a temperature sensor key from the “TPxx” family (like TP1A), which no primary source links to a named part. No public case on iPhone 12: the only TP3R cases found are on the XS Max (iFixit 973991) and the 1st-generation iPhone SE (iFixit 749276), both without a confirmed repair.

Which part to test first?

First rule out the known parts: known-good genuine battery and Lightning charging port assembly (on an iPhone 12 mini, missing sensors TG0B/TG0V were attributed to the Lightning connector, iFixit 743040).

The same code on other models

Field cases

Did you repair one? Tell us what worked: it improves the database for everyone.

Sources