how to fix P0304 code in Ford F-150 14th Generation (2021-2024)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Ford F-150 2021-2024. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the engine cover if necessary.
• Disconnect the ignition coil connector on cylinder 4.
• Remove the ignition coil by unscrewing its mounting bolts.
• Remove the old spark plug using a spark plug socket.
• Check the gap on the new spark plug and adjust to manufacturer specifications.
• Install the new spark plug and torque it to the manufacturer's specification (typically around 13 lb-ft).
• Reinstall the ignition coil and reconnect the connector.

3. Check and Replace Ignition Coil (if needed)

• Tools Required: Socket set, torque wrench.
• If the ignition coil is faulty, remove it as described above.
• Install a new ignition coil for cylinder 4 and torque it to the specified value.
• Ensure proper connection of the ignition coil connector.

4. Inspect and Clean Fuel Injector

• Tools Required: Fuel injector cleaning kit or replacement injector, safety goggles.
• Remove the fuel rail if necessary to access the injector for cylinder 4.
• Remove the fuel injector and inspect for clogs or damage.
• Clean the injector using a cleaning kit or replace it with a new one.
• Reinstall the fuel injector and reassemble the fuel rail.

5. Perform Compression Test (if misfire persists)

• Tools Required: Compression gauge.
• Remove spark plugs from all cylinders.
• Insert the compression gauge into the spark plug hole of cylinder 4.
• Crank the engine and record the compression reading.
• Compare with manufacturer specifications (typically 100-200 psi).
• If compression is low, further engine diagnosis may be necessary.