When your 2020 Subaru Impreza displays the P0304 code, the engine control module has detected recurring misfires in cylinder 4. The compact car's boxer engine requires understanding of Subaru's distinctive horizontally-opposed design for effective diagnosis and repair.
Understanding P0304 in the 2020 Impreza
The 2020 Impreza features the 2.0L FB20 boxer four-cylinder producing 152 horsepower. Subaru's horizontally-opposed configuration positions cylinder 4 at the rear of the left (driver's) bank. This unique engine layout affects accessibility and service approach compared to conventional inline designs.
Age-Related Considerations
Vehicles from 2020 may be approaching standard maintenance intervals. Spark plug electrode wear occurs over normal operation. Ignition coils degrade from years of heat cycling. The boxer's horizontal plug mounting can allow oil seepage if valve cover gaskets deteriorate. Consider maintenance history in your assessment.
Diagnostic Approach
Review maintenance records if available. Retrieve all codes noting mileage context. Access cylinder 4 on the left bank rear position. Check for oil contamination in the spark plug well. Test ignition coil output and spark plug condition. Verify fuel injector operation.
Repair Solutions
Replace spark plugs with Subaru-specified components. Address valve cover gasket leaks if oil contamination exists. Replace degraded ignition coils. The Impreza's compact engine bay requires methodical service approach.