DTC B278D Id Code Box Judgment Circuit: DTC Detecting Condition
WARNING: This page is about a different car, the 2016 Subaru Outback and 2016 Subaru Legacy. However, it is still accessible from the selected car via links, so may be relevant.
When the evaluation of the ID code box setting circuit via the hard wire is judged as none, ID code box communication is received. (at new registration)