i2c0 — I2C bus
On XS/XS Max/XR, the i2c0 bus serves, among others, the wide camera, the battery connector, the charging port and the sensors flex. Confirmed XS Max case: charging port replaced = fault solved (similar XR case).
On iPhone XS Max, iPhone XS, iPhone XR
Charging port flex (then wide camera, battery connector, sensors flex)
Medium confidenceVerified sourceI2C bus
First check
Replace the charging flex as a test; failing that, disconnect the sensors flex / camera and observe.