The engine air filter element for the FB25 2.5 liter four cylinder Boxer engine in a sixth generation (2015, 2016, 2017 & 2018) Subaru Outback should be checked and cleaned at every oil change and replaced every 30,000 miles. To view my DIY tutorial for changing the engine air filter (with the compatible replacement part numbers) by clicking on the text link or thumbnail image below.
2015-2018 Subaru Outback Engine Air Filter Replacement Guide
