DTC B2788: IGN1 Input Abnormal: DTC Detecting Condition
WARNING: This page is about a different car, the 2014 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
When mismatch occurs in the IG1 input of the steering lock control module for both LIN communication line input (IG1 input value of keyless access control module) and solid line input.