The P0302 trouble code on your 2020 Subaru Impreza indicates that cylinder 2 is experiencing misfires detected by the engine control module. The fifth-generation Impreza is powered by the 2.0L FB20D boxer four-cylinder producing 152 horsepower. This horizontally opposed engine with direct injection has specific characteristics for diagnosis.
FB20D Engine Overview
The 2.0L boxer positions cylinders horizontally opposed with cylinder 2 on the passenger (right) bank. Direct injection delivers fuel at high pressure for efficient combustion. The flat-four layout provides balanced operation and low center of gravity. Access differs from conventional inline engines.
Common Misfire Causes
Direct injection carbon buildup develops on intake valves since fuel doesn't wash over them. Ignition coil failure affects spark delivery. Spark plug fouling—potentially influenced by the horizontal position affecting oil drainage—reduces ignition energy. Fuel injector problems affect cylinder-specific delivery.
Symptom Recognition
The Impreza's boxer engine has a distinctive sound that changes noticeably with misfires. Rough idle, unusual vibration, and hesitation are typical. The compact car's driving character suffers when cylinder 2 doesn't contribute. Check engine light accompanies the condition.
Diagnostic Process
Scan for all codes and freeze frame data. Access cylinder 2 on the passenger bank. Test ignition coil and spark plug condition. Borescope inspect intake valves for carbon. Test fuel injector operation. Compression testing verifies mechanical health.
Repair Solutions
Replace spark plugs with OEM-specified units. Replace faulty ignition coils. Address carbon buildup through appropriate cleaning methods. Service fuel injectors if indicated. Standard boxer engine maintenance resolves most conditions.