what does a P0303 code mean for my Ford F-150

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 tools: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, and basic hand tools.
• Disconnect the negative battery terminal to ensure safety.

2. Replace Spark Plug

• Remove the ignition coil from cylinder 3.
• Unscrew the spark plug using a spark plug socket.
• Inspect the old spark plug; if it is worn or damaged, install a new spark plug with the correct gap as specified in the owner's manual.
• Torque the new spark plug to the manufacturer's specification (typically around 13-15 lb-ft).
• Reinstall the ignition coil and reconnect the wiring.

3. Inspect and Replace Ignition Coil

• If the spark plug was in good condition but the misfire persists, remove the ignition coil from cylinder 3.
• Test the ignition coil with a multimeter to check for proper resistance (refer to the vehicle's repair manual for specifications).
• If the ignition coil is faulty, replace it with a new one.
• Reinstall the ignition coil and ensure all connections are secure.

4. Check Fuel Injector

• If the issue continues, remove the fuel injector from cylinder 3.
• Clean the injector with a fuel injector cleaning kit or replace it if it is clogged or damaged.
• Reinstall the fuel injector securely.

5. Perform Compression Test

• If the misfire persists, perform a compression test on cylinder 3.
• Remove the spark plug, connect the compression tester, and crank the engine.
• Compare the compression results to the manufacturer's specifications. If the compression is low, further investigation into internal engine issues may be necessary.