how to fix P0304 misfire code in Ford F-150 14th Generation (2021-2024)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ford F-150 (2021-2024). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface with the engine off and cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug gap tool.
• Remove the ignition coil for cylinder 4 by unscrewing the retaining bolts and disconnecting the electrical connector.
• Unscrew and remove the spark plug from cylinder 4 using a socket wrench.
• Inspect the new spark plug and adjust the gap to the manufacturer specifications (typically around 0.030 inches for Ford engines).
• Install the new spark plug and torque it to the manufacturer’s specifications (usually around 13 ft-lbs).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Replace Ignition Coil (if necessary)

• Tools Required: Socket set.
• If the ignition coil appears damaged or is malfunctioning, remove it from cylinder 4.
• Install the new ignition coil and ensure it is seated properly.
• Reattach the electrical connector.

4. Check Fuel Injector (if necessary)

• Tools Required: Noid light or fuel injector tester.
• If the fuel injector is suspected to be faulty, remove it carefully.
• Test the fuel injector with a noid light to check for proper electrical function.
• If faulty, replace the fuel injector with a new one, ensuring proper seating and connection.

5. Reassemble and Restart

• Reconnect the negative battery terminal.
• Start the engine and allow it to idle for a few minutes.
• Monitor for any check engine light reactivation and listen for smooth operation.