how to fix P0304 misfire code in Honda Accord 8th Generation (2008-2012)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Honda Accord 2008-2012. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts; ensure the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Replace Spark Plug

• Tools Required: Socket set, torque wrench, dielectric grease.
• Remove the ignition coil cover if necessary.
• Disconnect the ignition coil connector on cylinder 4.
• Unscrew the ignition coil and remove it.
• Remove the spark plug using a spark plug socket.
• Inspect the old spark plug for wear; replace with a new spark plug if needed.
• Apply a small amount of dielectric grease to the spark plug threads.
• Install the new spark plug and torque to manufacturer specifications (typically 13-16 lb-ft).
• Reinstall the ignition coil and connector.

3. Test Ignition Coil

• Tools Required: Multimeter.
• Remove the ignition coil from cylinder 4.
• Test the primary and secondary resistance of the coil (consult the service manual for specific values).
• If the coil is faulty, replace it with a new one and reinstall.

4. Inspect Fuel Injector

• Tools Required: Fuel pressure gauge, injector cleaning kit.
• Check the fuel pressure to ensure it meets specifications.
• If pressure is low, inspect the fuel pump and filter.
• If the fuel injector is suspected to be clogged, use an injector cleaning kit or replace the injector.

5. Perform Compression Test

• Tools Required: Compression tester.
• Remove all spark plugs for accurate testing.
• Insert the compression tester into cylinder 4.
• Crank the engine several times to take a reading.
• Compare the reading with manufacturer specifications (typically around 180-200 psi).
• If the compression is low, investigate potential internal engine issues (valve problems, head gasket leaks).