how to fix P0303 misfire code in Ford F-150 14th Generation (2021-2024)

Learn how to diagnose and fix P0303 cylinder 3 misfire in Ford F-150 14th Generation. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, noid light.
• Disconnect the negative battery terminal to ensure safety while working on the electrical components.

2. Replace Spark Plug

• Sub-steps:
  1. Remove the ignition coil from cylinder 3 by unscrewing the retaining bolts.
  2. Disconnect the electrical connector from the ignition coil.
  3. Remove the spark plug using a spark plug socket and ratchet.
  4. Inspect the old spark plug for signs of wear (carbon buildup, oil, etc.).
  5. Install a new spark plug (ensure it’s gapped correctly to manufacturer specifications).
  6. Reinstall the ignition coil, reconnect the electrical connector, and secure it with the retaining bolts.

3. Replace Ignition Coil (if necessary)

• Sub-steps:
  1. If the ignition coil was found defective, remove it as described in the previous section.
  2. Install the new ignition coil by reversing the removal procedure.
  3. Ensure all connections are secure.

4. Inspect and Replace Fuel Injector (if necessary)

• Sub-steps:
  1. Disconnect the fuel injector connector for cylinder 3.
  2. Remove the fuel rail assembly if needed to access the injector.
  3. Remove the fuel injector from the rail and inspect for blockage or damage.
  4. Replace with a new fuel injector if it is faulty and reinstall the fuel rail assembly.

5. Verify Compression

• Sub-steps:
  1. Remove the spark plug from cylinder 3.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine to obtain the compression reading.
  4. Compare the reading against the manufacturer's specifications; if low, further investigation is needed.