The P0302 diagnostic code on your 2020 Subaru Ascent indicates cylinder 2 is experiencing misfires detected by the engine control module. The Ascent is powered exclusively by the 2.4L FA24F turbocharged boxer four-cylinder producing 260 horsepower. This direct-injection turbo engine has specific characteristics affecting misfire diagnosis.
FA24F Turbo Engine Overview
The 2.4L turbo is a horizontally opposed four-cylinder with cylinder 2 on the passenger bank. The turbocharged direct-injection design provides substantial power for the three-row SUV. Higher cylinder pressures from turbocharging increase stress on ignition components compared to naturally aspirated engines.
Common Misfire Causes
Direct injection carbon buildup develops on intake valves over time. Boost pressure irregularities from wastegate or blow-off valve issues can cause misfires. Ignition coil failure affects spark delivery—the turbo's higher pressures demand strong spark. Spark plug wear reduces ignition energy. Fuel injector problems affect delivery.
Symptom Recognition
The boxer turbo's distinctive sound changes with misfires. The large SUV exhibits rough idle, vibration through the cabin, and hesitation during acceleration. The three-row vehicle's driving character suffers when cylinder 2 misfires. Check engine light accompanies the condition.
Diagnostic Process
Scan for all codes including boost-related codes. Access cylinder 2 on the passenger bank. Test ignition components. Verify boost pressure and system integrity. Borescope inspect intake valves. Test fuel injector operation. Compression testing verifies health.
Repair Solutions
Replace spark plugs and coils with quality components suitable for turbo application. Address carbon buildup through cleaning. Repair boost system issues if identified. Service fuel injectors as needed.