how to fix P0303 code on Ford F-150 12th Generation (2009-2014)

Learn how to diagnose and fix P0303 cylinder 3 misfire in Ford F-150 12th Generation. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

• Remove the engine cover if necessary.
• Locate cylinder 3 (usually the second cylinder on the driver's side).
• Remove the ignition coil by unscrewing the bolt and disconnecting the electrical connector.
• Remove the spark plug using a spark plug socket and ratchet.
• Inspect the old spark plug; if fouled or damaged, replace it with a new one (ensure proper gap according to manufacturer specifications).
• Install the new spark plug and torque it to the manufacturer's specification (typically around 13-15 ft-lbs).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Test Ignition Coil and Fuel Injector

• If the spark plug replacement did not resolve the issue, check the ignition coil by swapping it with a functioning coil from another cylinder.
• Clear the P0303 code using the OBD-II scanner and take the vehicle for a test drive.
• If the code returns for cylinder 3, inspect the fuel injector by removing it and checking for clogs. Clean or replace as necessary.

4. Compression Test (if required)

• If misfire persists, perform a compression test on cylinder 3.
• Remove spark plugs from all cylinders for accurate compression readings.
• Insert the compression gauge into cylinder 3 and crank the engine to take a reading.
• Compare the result with the manufacturer's specifications; replace the head gasket or repair the cylinder if compression is low.