how to fix P0304 code in 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 all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Replace Spark Plug

1. Remove the engine cover (if applicable) using a socket set.
2. Locate the spark plug for cylinder 4.
3. Use a spark plug socket to remove the old spark plug.
4. Check and adjust the gap on the new spark plug to manufacturer specifications (usually around 0.054 inches for Ford).
5. Install the new spark plug and torque it to the specified value (approximately 13 lb-ft).

3. Inspect and Replace Ignition Coil (if necessary)

1. Remove the ignition coil connector and the bolt securing the coil.
2. Carefully pull out the ignition coil.
3. If the coil is faulty, install a new ignition coil and secure it with the bolt.
4. Reconnect the ignition coil connector.

4. Test Fuel Injector

1. Disconnect the fuel injector connector for cylinder 4.
2. Use a multimeter to check the resistance of the injector (should be within manufacturer specifications).
3. If the injector is faulty, replace it by removing the retaining clips and gently pulling it out of the fuel rail.
4. Install a new fuel injector and reconnect the fuel injector connector.

5. Compression Test (if misfire persists)

1. Remove spark plugs from all cylinders.
2. Insert a compression gauge into the spark plug hole of cylinder 4.
3. Crank the engine and record the compression reading.
4. If the compression is low, further investigation is needed for internal engine issues.