The P0304 code in your 2021 Ford Bronco Sport indicates the engine management system has detected persistent cylinder 4 misfires. As the first model year for this compact adventure SUV, understanding its EcoBoost engine options helps target diagnosis for either the base 1.5L three-cylinder or the available 2.0L four-cylinder powerplant.
Understanding P0304 in the 2021 Bronco Sport
The Bronco Sport offers two EcoBoost engine choices: a 1.5L turbocharged three-cylinder in base and Big Bend trims, or a 2.0L turbocharged four-cylinder in Badlands and First Edition models. Since P0304 specifically indicates cylinder 4, this code only applies to Bronco Sports equipped with the 2.0L four-cylinder engine. On this inline-four, cylinder 4 sits at the rear position nearest the firewall.
2.0L EcoBoost Misfire Causes
The 2.0L EcoBoost faces typical turbocharged direct injection challenges. Elevated cylinder pressures increase ignition system demands significantly. Spark plugs experience accelerated electrode wear requiring closer attention to replacement intervals. Direct injection allows carbon deposit formation on intake valves. The Bronco Sport's adventure-oriented use may expose electrical connectors to moisture and debris that affect ignition system reliability.
Diagnostic Process
Confirm the P0304 code and verify the vehicle has the 2.0L engine rather than the three-cylinder. Retrieve freeze frame data showing driving conditions when the misfire occurred. Access the ignition components by removing necessary covers. Inspect spark plug condition, ignition coil integrity, and fuel injector operation systematically. Consider environmental factors relevant to the vehicle's usage patterns.
Repair Procedures
Replace spark plugs using Ford-specified components for the 2.0L EcoBoost application. Ensure proper installation torque to prevent thread damage in the aluminum cylinder head. Test and replace degraded ignition coils. Address any carbon accumulation through appropriate cleaning procedures. Inspect and clean connectors if moisture exposure is suspected.