Troubleshooting Subaru Start Stop
Mitchell 1 reports that the Subaru Techline has been receiving an increased amount of calls on Hybrid Subaru vehicles with a concern of no Auto Start Stop operation, with or without DTCs.
If you encounter one of these issues, a necessary step to include in your diagnosis should be to check the 12V restart battery condition with the DSS. They have seen a bad restart battery accompany DTCs related to the integrated starter generator (ISG) along with disabling both the Auto Start Stop and EV travelling modes.
If DTCs are involved, the applicable troubleshooting procedure should be followed including battery testing.