Five problems related to manifold/header/muffler/tail pipe have been reported for the 2015 Subaru Outback. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2015 Subaru Outback based on all problems reported for the 2015 Outback.
The muffler makes a rattling or growling noise when idling or coasting. The noise disappears when accelerating.
I have this issue with my muffler. TSB 09-66-16 rear muffler shell rigidity enhancement this bulletin announces a change in the production procedure for the rear muffler assembly. Spot-weld locations securing the outer shell portion have been changed to improve overall rigidity. A gap may develop at the spot welded seam as a result of repeated thermal shock (heating / cooling) which occurs during normal use. The gap does not create an exhaust leak. In some cases, a rattling sound from the muffler may develop.
Noted over a period of several weeks, an increase in exhaust noise from the front of the car. The cabin would fill with exhaust fumes when stopped with the engine running. I took the car to the dealer twice to have the issue diagnosed and both times they indicated that no issue was found. On the third trip, they confirmed a hole in the exhaust manifold and initially refused to replace it under warranty, even though the vehicle was covered under the pzev emissions warranty and extended vehicle coverage. After pointing out the pzev coverage, the dealer replaced the manifold.
We noticed an exhaust leak (noisy) on our 2015 Outback, upon inspection by the dealer they determined the catalytic converter needed to be replaced, they initially rejected our warantee claim because Subaru authorizes replacement only if a mil is present. After some discussion the dealer (Subaru) agreed to replace as "good will". We live in the northeast and it seems road salt and sand cause the converter to rust prematurely, the location of the converted is aft of the exhaust manifold and at the base of the passenger compartment, there is a risk of carbon monoxide poisoning with these types of leaks, and it is unheard of that these parts fail after three years.
Excessive exhaust entering passenger cabin anytime the engine is running because of crack in flex pipe on the exhaust manifold that occurred with less than 60k miles.