Section 4 (Automatic Transaxle (Diagnostics) (IMPREZA)): General Description: Inspection: Battery
WARNING: This page is about a different car, the 2021 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
Check the battery. Ref. to STARTING/CHARGING SYSTEMS (H4DO (EXCEPT FOR HEV))>BATTERY>INSPECTION .