A P0302 code on your 2018 Subaru Outback indicates the engine control module has detected misfires in cylinder 2. The fifth-generation 2018 Outback offers the 2.5L boxer four-cylinder or the 3.6L boxer six-cylinder. Both engines feature Subaru's horizontally opposed design with specific diagnostic considerations.
2018 Engine Options
The 2.5L FB25 produces 175 horsepower using port injection. The 3.6L EZ36 produces 256 horsepower also with port injection. Unlike newer Outbacks, these engines don't have direct injection, meaning carbon buildup is less of a concern. Cylinder 2 is on the passenger side on both configurations.
Common Misfire Causes
The 2018 Outback engines experience standard misfire causes: ignition coil failure, spark plug wear, fuel injector clogging, and vacuum leaks. The horizontal cylinder position can affect oil drainage patterns. Head gasket issues, while improved from earlier generations, remain a consideration on higher-mileage examples.
Symptom Recognition
Boxer engine misfires create distinctive symptoms. The flat-four or flat-six's characteristic sound changes noticeably. Rough idle, vibration, and hesitation affect driving. The check engine light illuminates when misfires are detected.
Diagnostic Approach
Identify your engine type. Scan for all codes and freeze frame data. Access cylinder 2 for spark plug and coil inspection. Test fuel injector operation. Check for vacuum leaks. Compression testing verifies cylinder health—important for checking head gasket condition on boxer engines.
Repair Solutions
Replace spark plugs with OEM-specified units. Replace faulty ignition coils. Service fuel injectors if indicated. Repair vacuum leaks. Address any compression issues discovered during testing.