The P0304 code in your 2023 Subaru Ascent indicates the powertrain control module has detected persistent misfires in cylinder 4. The three-row SUV's turbocharged boxer engine requires understanding of both forced induction demands and Subaru's unique horizontally-opposed architecture.
Understanding P0304 in the 2023 Ascent
The 2023 Ascent continues with the exclusive 2.4L FA24 turbocharged boxer four-cylinder producing 260 horsepower. Subaru's horizontally-opposed configuration positions cylinder 4 at the rear of the left (driver's) bank. The turbocharger adds complexity to standard misfire diagnosis.
Turbocharged Boxer Considerations
The boosted boxer operates under elevated cylinder pressures requiring robust ignition components. Spark plugs rated for turbocharged applications must reliably ignite compressed charges. Direct injection contributes to carbon accumulation potential. The Ascent's family utility means varied driving conditions affecting engine operation.
Systematic Diagnostics
Retrieve all codes checking for boost-related faults accompanying P0304. Analyze freeze frame conditions noting boost pressure and load. Locate cylinder 4 on the left bank rear position. Test ignition coil output against turbo specifications. Inspect spark plug condition. Verify fuel injector operation.
Effective Repairs
Install Subaru-approved spark plugs designed for turbocharged operation. Clean spark plug wells before removal. Replace ignition coils testing outside specifications. Address fuel system concerns. Quality components ensure reliable turbo operation.