The P0304 code in your 2022 Subaru Forester indicates the powertrain control module has detected persistent misfires in cylinder 4. The compact SUV's boxer four-cylinder engine requires understanding of this distinctive horizontally-opposed configuration for effective diagnosis.
Understanding P0304 in the 2022 Forester
The 2022 Forester features the 2.5L FB25 boxer four-cylinder. Subaru's horizontally-opposed design positions cylinders on opposite sides of the crankshaft—cylinder 4 sits at the rear of the left (driver's) bank. This configuration creates unique service access compared to inline engines commonly found in competitors.
Boxer-Specific Considerations
The flat-four boxer mounts spark plugs horizontally. This orientation can allow debris and moisture accumulation in spark plug wells if left unattended. The configuration provides excellent engine balance but requires specific service approaches. Standard misfire causes—ignition and fuel system wear—apply with Subaru-unique accessibility.
Diagnostic Process
Retrieve all codes and freeze frame data. Locate cylinder 4 at the rear of the left bank. Working space may be limited around the inner fender area. Test ignition coil output and inspect spark plug condition. Verify fuel injector operation through appropriate methods.
Repair Implementation
Install Subaru-approved spark plugs at proper torque. Clean around plug wells thoroughly before removal. Replace degraded ignition coils. Address fuel system concerns as identified during diagnosis.