When your 2021 Ford Bronco displays the P0304 code, the engine control module has identified consistent misfires in cylinder 4. The reborn off-road icon uses turbocharged EcoBoost engines.
2021 Bronco Engine Options
The 2021 Bronco offers the 2.3L EcoBoost four-cylinder (300 hp) or 2.7L EcoBoost V6 (330 hp). On the inline-4, cylinder 4 is the rearmost. On the V6, cylinder 4 is on one bank.
Common Causes
- Ignition Coil Failure: Turbo boost stresses ignition systems
- Spark Plug Issues: EcoBoost engines require specific plugs
- Boost System Leaks: Off-road use can damage components
- Fuel Injector Problems: Direct injection deposits
- Environmental Exposure: Dust and water ingestion
Diagnostic Approach
Use Ford diagnostics for EcoBoost-specific data. Check for damage from off-road use. Monitor boost and misfire data. Test ignition components systematically.
Repair Solutions
Replace failed ignition coils with Motorcraft components. Install Ford-specified spark plugs. Repair boost leaks. Inspect for off-road damage. Dealer service for warranty coverage.