The P0304 code in your 2022 Subaru Crosstrek indicates the powertrain control module has detected persistent misfires in cylinder 4. Understanding the compact crossover's boxer engine configuration enables targeted diagnosis for this common combustion problem.
Understanding P0304 in the 2022 Crosstrek
The 2022 Crosstrek features either the 2.0L FB20 or 2.5L FB25 boxer four-cylinder depending on trim level. Subaru's horizontally-opposed design positions cylinder 4 at the rear of the left (driver's) bank. This unique engine architecture requires specific diagnostic and service approaches.
Flat-Four Misfire Causes
The boxer engine mounts spark plugs horizontally rather than vertically. This orientation creates unique service considerations. Standard ignition wear—coil degradation and plug electrode erosion—remains the primary cause. The horizontal mounting can allow debris accumulation in spark plug wells requiring careful cleaning.
Diagnostic Process
Determine your engine size. Retrieve all codes and analyze freeze frame conditions. Locate cylinder 4 at the left bank rear position. Access typically requires working around the inner fender. Test ignition coil output and spark plug condition systematically. Verify fuel injector operation.
Repair Implementation
Install Subaru-approved spark plugs at proper specifications. Clean plug wells thoroughly before removal. Replace ignition coils testing outside acceptable ranges. Address fuel system concerns as identified.