When your 2023 Honda Civic displays the P0304 code, the powertrain control module has identified consistent misfires in cylinder 4. The 2023 Civic's inline-4 engines position cylinder 4 at the rear.
2023 Civic Engine Options
The 2023 Civic offers the 2.0L naturally aspirated (158 hp) or 1.5L turbocharged (180 hp) four-cylinder. Cylinder 4 is the rearmost cylinder on both configurations.
Typical Causes
- Ignition Coil Problems: Rear cylinder heat exposure
- Spark Plug Condition: Engine-specific requirements
- Fuel Injector Issues: Direct injection on turbo model
- Carbon Accumulation: 1.5L turbo valve deposits
- Intake System Leaks: Vacuum or boost leaks
Diagnostic Process
Use Honda diagnostics for detailed access. Monitor misfire counts and boost data on turbo models. Test ignition components systematically.
Repair Recommendations
Replace faulty ignition coils with OEM parts. Install properly specified spark plugs. Address carbon buildup on turbo models. Repair intake system leaks.