how to fix P0303 misfire code in Ford F-150 12th Generation (2009-2014)

Learn how to diagnose and fix P0303 cylinder 3 misfire in Ford F-150 (2009-2014). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before proceeding with any work.

2. Replace Spark Plug

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the ignition coil from cylinder 3:
  • Unplug the electrical connector.
  • Remove the bolts securing the ignition coil and gently pull it out.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug condition and replace if necessary.
• Install the new spark plug, ensuring it is gapped correctly according to manufacturer specifications (typically around 0.054 inches for Ford F-150).
• Torque the spark plug to the specified value (usually around 13 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Replace Ignition Coil (if necessary)

• If the ignition coil is found faulty, replace it:
  • Follow the same steps as above to remove the ignition coil.
  • Install the new ignition coil and secure it with bolts.
  • Reconnect the electrical connector.

4. Test Fuel Injector

• If the spark plug and ignition coil are functioning properly, test the fuel injector:
  • Disconnect the fuel injector connector.
  • Use a multimeter to check resistance (should be within manufacturer specifications).
  • If faulty, replace the fuel injector by removing the fuel rail and installing the new injector.

5. Compression Test (if necessary)

• If misfire persists after replacing the spark plug and ignition coil:
  • Perform a compression test on cylinder 3.
  • If compression is low, further investigation is needed for potential issues like worn piston rings or valve problems.