how to troubleshoot my Ford F-150 13th Generation (2015-2020) with a P0303 code

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

Solution

1. Preparation

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

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Locate the spark plug for cylinder 3 (refer to the owner’s manual for specific location).
  3. Using a spark plug socket and ratchet, remove the spark plug.
  4. Inspect the spark plug for wear, deposits, or damage. Replace if necessary.
  5. Gap the new spark plug according to manufacturer specifications (typically 0.040 inches for Ford).
  6. Install the new spark plug, tightening to manufacturer torque specifications (usually around 13 lb-ft).

3. Check and Replace Ignition Coil

• Sub-steps:
  1. Disconnect the electrical connector from the ignition coil for cylinder 3.
  2. Remove the ignition coil by unscrewing any retaining bolts.
  3. Inspect the ignition coil for cracks or other damage.
  4. Replace the ignition coil if it’s defective.
  5. Reinstall the ignition coil, securing it with the retaining bolts and reconnecting the electrical connector.

4. Inspect Fuel Injector

• Sub-steps:
  1. Locate the fuel injector for cylinder 3.
  2. Disconnect the electrical connector from the fuel injector.
  3. Remove any retaining clips and carefully pull out the fuel injector.
  4. Inspect the fuel injector for blockages or damage.
  5. Test the fuel injector's resistance using a multimeter (should be within the specified range).
  6. Replace the fuel injector if it’s faulty.
  7. Reinstall the fuel injector, ensuring it is seated properly and reconnect the electrical connector.

5. Compression Test (if needed)

• Sub-steps:
  1. Remove the spark plug for cylinder 3 again for access.
  2. Insert the compression gauge into the spark plug hole.
  3. Crank the engine to take the reading.
  4. Compare the compression reading to manufacturer specifications (typically around 120-175 psi).
  5. If compression is low, further investigation into engine internals may be required.