Subaru of America, Inc. (Subaru) is initiating a service campaign for certain 2015-2018 Legacy and Outback 2.5L SULEV vehicles. This campaign involves replacement of the front exhaust pipe assembly, which includes the catalytic converter. Due to an improper part number supersession for the EPF assembly, certain SULEV vehicles which had the EPF replaced by an authorized Subaru retailer may have had a non-SULEV specification part installed. Although there is no safety risk or noticeable change in vehicle operation, performance of the emission system may be insufficient to comply with required specifications.