15' outback evap leak code. No leaks.

[infernalmarine]

I recently got ahold of a 2015 outback that has a persistent evap gross leak code p0455. The system has been smoked 2 times. I brought it to a subaru dealership, they said they couldn't find anything wrong with the evap system but tried to upsell me a complete engine reseal and charged me $300 to tell me they wouldn't do anything. What do I do?