how to fix P0304 code on my Ford F-150 Fourteenth Generation (2021-present)

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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Ignition Components

• Sub-steps:
  • Remove the engine cover if applicable.
  • Disconnect the electrical connector from the ignition coil for cylinder 4.
  • Remove the ignition coil bolt using a socket set and lift the coil out.
  • Inspect the spark plug; remove it using a spark plug socket and check for wear or damage.
  • Replace the spark plug with a new one (OEM recommended) if necessary. Torque to manufacturer specifications (typically around 13-15 lb-ft).
  • If the ignition coil is damaged, replace it with a new one.

3. Test and Replace Fuel Injector

• Sub-steps:
  • Disconnect the fuel injector connector for cylinder 4.
  • Remove the fuel rail if necessary (ensure to relieve fuel pressure first).
  • Remove the fuel injector and check for clogging or damage.
  • Replace the fuel injector if it is faulty, ensuring proper seating and connection.
  • Reassemble the fuel rail and reconnect the injector electrical connector.

4. Compression Test

• Sub-steps:
  • Remove the spark plug for cylinder 4 and insert the compression gauge.
  • Crank the engine and note the compression reading.
  • If the reading is below manufacturer specifications, further investigation into the engine internals may be necessary (valves, piston rings).

5. Reassemble and Clear Codes

• Sub-steps:
  • Reconnect all components and ensure all bolts are torqued to specifications.
  • Reconnect the battery.
  • Start the engine and let it idle; monitor for any misfire symptoms.
  • Use the OBD-II scanner to clear the P0304 code and any other stored codes.