how to fix P0303 misfire code on 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.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Replace Spark Plug

• Remove Engine Cover (if applicable):
  • Use a socket set to remove any bolts securing the engine cover.
• Remove Spark Plug:
  • Use a spark plug socket to carefully unscrew and remove the spark plug from cylinder 3.
• Install New Spark Plug:
  • Apply anti-seize compound to the threads of the new spark plug.
  • Hand-tighten the spark plug, then torque it to the manufacturer’s specification (typically around 13 lb-ft).

3. Replace Ignition Coil

• Remove Ignition Coil:
  • Disconnect the electrical connector from the ignition coil.
  • Remove the bolt securing the coil and pull it out of the spark plug tube.
• Install New Ignition Coil:
  • Insert the new ignition coil into the spark plug tube and secure it with the bolt.
  • Reconnect the electrical connector.

4. Test Fuel Injector

• Remove Fuel Injector Connector:
  • Disconnect the fuel injector connector for cylinder 3.
• Test Injector with Noid Light:
  • Connect a noid light to the injector connector and crank the engine. The light should blink, indicating injector operation.
• Replace Injector (if necessary):
  • If the injector is not firing, replace it by removing the rail and following the appropriate steps for injector replacement.

5. Perform Compression Test (if misfire persists)

• Remove Spark Plug Again:
  • Remove the spark plug of cylinder 3.
• Insert Compression Tester:
  • Screw in a compression tester and crank the engine.
• Check Compression Reading:
  • Compare the compression reading to the manufacturer’s specifications (typically should be above 100 psi).