how to fix P0304 misfire code in Ford F-150 13th Generation (2015-2020)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ford F-150 (2015-2020). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts before beginning the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 4:
  • Disconnect the electrical connector.
  • Unscrew the mounting bolts and pull the coil off.
• Remove the spark plug:
  • Use a spark plug socket and ratchet to unscrew the spark plug from the cylinder head.
• Inspect the spark plug for wear:
  • Replace if the electrode is worn or if there are signs of oil fouling.
• Install the new spark plug:
  • Torque to manufacturer specifications (typically around 13-15 lb-ft).
• Reinstall the ignition coil.

3. Inspect and Replace Ignition Coil

• If the ignition coil is faulty:
  • Remove it as described above.
  • Install a new ignition coil for cylinder 4.
  • Ensure proper seating and reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Remove the fuel injector for cylinder 4:
  • Disconnect the electrical connector and fuel line.
  • Unscrew any mounting bolts and pull the injector from the rail.
• Clean the injector with a cleaning solution or replace it if necessary.
• Reinstall the injector, reconnect the fuel line, and electrical connector.

5. Compression Test (if needed)

• If misfire persists, perform a compression test:
  • Remove spark plugs from cylinders 1-4.
  • Insert the compression tester into cylinder 4.
  • Crank the engine for several seconds and note the reading.
  • Compare with manufacturer specifications (typically 120-150 psi).
• If compression is low, further investigation into valve or piston issues may be required.