how to fix the P0304 code on my Ford F-150 12th Generation (2009-2014)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ford F-150 (2009-2014). Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the battery to prevent electrical shorts.

2. Replace Spark Plug

• Remove the engine cover if applicable.
• Locate the spark plug for cylinder 4 (refer to the engine layout).
• Use a spark plug socket and ratchet to remove the old spark plug.
• Inspect the old spark plug for signs of wear or damage (e.g., carbon buildup).
• Install a new spark plug, ensuring the gap is set to manufacturer's specifications (typically 0.054 inches).
• Torque the spark plug to the specified value (usually around 13 lb-ft).

3. Inspect/Replace Ignition Coil

• Locate the ignition coil for cylinder 4.
• Disconnect the electrical connector from the ignition coil.
• Remove the mounting bolt using a socket wrench.
• Remove the ignition coil and inspect for damage.
• Replace with a new ignition coil if necessary.
• Reinstall the ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

• Locate the fuel injector for cylinder 4.
• Disconnect the electrical connection and fuel line (use caution as fuel may spill).
• Remove the fuel injector from the intake manifold.
• Inspect for clogs or damage.
• Replace with a new fuel injector if necessary.
• Reinstall and reconnect the fuel line and electrical connector.

5. Conduct Compression Test (if needed)

• Remove spark plug from cylinder 4 and install a compression gauge.
• Crank the engine a few times to get a reading.
• Compare the compression reading to specifications (usually around 120-180 psi).
• If the compression is low, further investigation into engine internals may be necessary.