DTC U123C: Lost Communication With High Beam Assist Control Module

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

DTC detecting condition:

No data is received from high beam assist module.

NOTE:

Check if the customize setting is correct.
Perform the diagnosis for LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE