how to fix the P0304 code on my Ford F-150 12th Generation (2009-2014)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ford F-150 (2009-2014). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal.
• Ensure the engine is cool before starting work.

2. Replace Spark Plug

1. Remove the ignition coil cover by unscrewing any fasteners.
2. Disconnect the ignition coil connector from the coil for cylinder 4.
3. Remove the ignition coil from cylinder 4.
   • Tools required: Socket set, torque wrench.
4. Using a spark plug socket, carefully remove the spark plug from cylinder 4.
5. Inspect the old spark plug for signs of wear or fouling; replace it with a new spark plug.
   • Ensure the gap is set to the manufacturer's specifications.
6. Reinstall the spark plug and torque it to the manufacturer's specification (typically around 13-20 ft-lbs).
7. Reinstall the ignition coil and reconnect the connector.

3. Replace Ignition Coil (if necessary)

1. If the ignition coil is defective, remove it as described in the previous step.
2. Install the new ignition coil for cylinder 4.
3. Reconnect the ignition coil connector and ensure it is secure.

4. Inspect and Replace Fuel Injector (if necessary)

1. If the fuel injector is suspected, remove the intake manifold if needed for access.
2. Disconnect the fuel line and electrical connector from the fuel injector for cylinder 4.
3. Remove the injector and inspect it for clogs or damage.
4. Replace with a new fuel injector if necessary, ensuring proper O-ring placement.
5. Reconnect the fuel line and electrical connector.