how to fix P0304 code on my Honda Civic 11th Generation (2022-Present)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Honda Civic 11th 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.
• Allow the engine to cool before beginning work on the ignition system.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coil cover if applicable.
• Use the spark plug socket to remove the spark plug from cylinder 4.
• Inspect the spark plug for damage or excessive wear. If worn, replace it with a new one.
• Torque the new spark plug to manufacturer specifications (typically around 13-15 lb-ft for Honda engines).

3. Test and Replace Ignition Coil

• Tools Required: Multimeter.
• Disconnect the ignition coil connector and remove it from cylinder 4.
• Test the ignition coil's resistance using a multimeter. Compare readings to manufacturer specifications.
• If the coil is faulty, replace it with a new ignition coil.
• Reinstall the new ignition coil, ensuring it connects securely.

4. Inspect Fuel Injector

• Tools Required: Fuel injector cleaning kit or replacement injector.
• Disconnect the fuel injector connector for cylinder 4.
• Perform a resistance check on the injector using a multimeter. Replace if out of specification.
• If cleaning, use an injector cleaning kit to flush the injector. If not, replace with a new injector.
• Reconnect the injector and ensure it is securely in place.

5. Check for Vacuum Leaks

• Visually inspect the vacuum lines and intake manifold for any cracks or disconnections.
• Use a smoke machine or carburetor cleaner to check for leaks around the intake manifold and vacuum lines.
• Repair any leaks found, as they can lead to misfires.