A P0304 diagnostic code on your 2021 Ford Mustang indicates the engine control module has detected repeated misfires in cylinder 4. The iconic muscle car offers turbocharged four-cylinder and V8 options.
2021 Mustang Engine Options
The 2021 Mustang offers the 2.3L EcoBoost four-cylinder (310 hp) or 5.0L Coyote V8 (460-480 hp depending on variant). On the inline-4, cylinder 4 is rearmost. On the V8, cylinder 4 is on the driver's side.
Common Causes
- Ignition Coil Failure: High-performance applications stress ignition
- Spark Plug Issues: Performance engines require quality plugs
- Boost System Leaks: EcoBoost sensitive to intake leaks
- Fuel Injector Problems: Direct injection deposits
- Carbon Buildup: Both engines use direct injection
Diagnostic Approach
Use Ford diagnostics for detailed access. Identify your engine type. Monitor boost on EcoBoost. Test ignition components systematically.
Repair Solutions
Replace failed ignition coils with Motorcraft or performance components. Install properly specified spark plugs. Repair boost leaks. Address carbon buildup.