The P0304 diagnostic trouble code indicates your 2023 Ford Bronco's powertrain control module has detected consistent misfires in cylinder 4. Whether your Bronco runs the 2.3L EcoBoost four-cylinder or the 2.7L EcoBoost V6, this code requires prompt attention to protect both engine performance and the catalytic converter from unburned fuel damage.
Understanding P0304 in the 2023 Ford Bronco
Ford's EcoBoost engines use direct fuel injection and turbocharging to maximize power output. Cylinder 4's location varies by engine configuration—on the 2.3L inline-four, it's the rearmost cylinder near the firewall, while on the 2.7L V6, it's positioned on the rear bank. Both configurations expose cylinder 4 to specific thermal and accessibility challenges that can contribute to misfire conditions.
Common Causes for Cylinder 4 Misfires
The turbocharged EcoBoost engines face unique challenges. Carbon buildup on intake valves is common with direct injection systems since fuel doesn't wash over the valves. Ignition coils experience higher stress due to boosted cylinder pressures. Additionally, the high-pressure fuel system must maintain precise injection timing, and any deviation affects combustion quality.
Diagnostic Approach
Begin with an electronic scan to confirm the P0304 code and check for related codes affecting fuel or ignition systems. Inspect the cylinder 4 ignition coil and spark plug, noting any oil contamination from valve cover gasket leaks. Check fuel injector operation using a mechanics stethoscope or noid light test. For vehicles with higher mileage, carbon buildup inspection via borescope may reveal intake valve deposits.
Repair Solutions
Basic repairs include spark plug replacement with Ford-specified components rated for turbocharged applications, ignition coil replacement, and fuel injector cleaning or replacement. Carbon deposits may require professional walnut shell blasting of intake valves. Verify the turbocharger wastegate operates correctly, as boost control issues can cause detonation-related misfires.