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 necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.

Tools Required:

• OBD-II scanner
• Spark plug socket
• Torque wrench
• Multimeter
• Compression tester
• Fuel injector cleaner (if needed)

2. Replace Spark Plug

1. Remove the engine cover if applicable.
2. Disconnect the ignition coil connector for cylinder 3.
3. Unscrew the ignition coil from the cylinder head.
4. Remove the spark plug using a spark plug socket.
5. Install a new spark plug, ensuring it is gapped correctly (manufacturer spec).
6. Reinstall the ignition coil and reconnect the connector.

3. Check and Replace Ignition Coil

1. If the spark plug replacement does not resolve the issue, test the ignition coil with a multimeter (check resistance).
2. If the ignition coil is faulty, remove it from the engine.
3. Install a new ignition coil in cylinder 3.
4. Reconnect the ignition coil harness.

4. Inspect and Clean Fuel Injector

1. If the issue persists, remove the fuel injector from cylinder 3.
2. Clean the injector using a fuel injector cleaner or replace it if it is defective.
3. Reinstall the injector, ensuring it is properly seated.

5. Compression Test

1. If misfire continues, perform a compression test on cylinder 3.
2. Compare the results with the manufacturer's specifications.
3. Address any issues found (e.g., valve problems, head gasket failure).