how to fix P0303 misfire code on Ford F-150 13th Generation (2015-2020)

Learn how to diagnose and fix P0303 cylinder 3 misfire in Ford F-150 (2015-2020). 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, fuel injector tester, vacuum gauge.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Replace Spark Plug and Ignition Coil

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the electrical connector from the ignition coil for cylinder 3.
  3. Remove the ignition coil using a socket wrench.
  4. Inspect and replace the spark plug in cylinder 3. Use the manufacturer’s recommended spark plug type and gap specifications.
  5. Install the new ignition coil, ensuring it is seated properly.
  6. Reconnect the electrical connector to the ignition coil.

3. Inspect and Test Fuel Injector

• Sub-steps:
  1. Disconnect the fuel injector connector for cylinder 3.
  2. Use a noid light to check for proper electrical signal to the injector when the engine is cranked.
  3. If the signal is present, remove the fuel injector and clean it using an ultrasonic cleaner or replace it if necessary.
  4. Reinstall the fuel injector and reconnect the electrical connector.

4. Perform Compression Test

• Sub-steps:
  1. Remove the spark plug from cylinder 3.
  2. Insert the compression tester into the spark plug hole.
  3. Crank the engine for a few seconds and record the compression reading.
  4. Compare the reading to the manufacturer’s specifications. If it is low, further inspection of the piston rings or valves may be needed.

5. Check for Vacuum Leaks

• Sub-steps:
  1. Inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  2. Use a vacuum gauge to measure the vacuum at idle; a low reading may indicate a leak.
  3. Repair or replace any damaged hoses as necessary.