how to diagnose P0304 code on Honda Accord 8th Generation (2008-2012)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Honda Accord 8th Generation. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety during the repair.
• Allow the engine to cool down.

2. Replace Spark Plug

1. Remove the engine cover if applicable.
2. Locate the spark plug for cylinder 4 (usually the fourth one from the timing belt).
3. Use a socket wrench and spark plug socket to unscrew the spark plug.
4. Inspect the old spark plug for wear; replace with a new spark plug to manufacturer specifications (typically, NGK or DENSO).
5. Torque the new spark plug to the manufacturer's specification (usually around 13-15 lb-ft).

3. Test or Replace Ignition Coil

1. Disconnect the ignition coil connector.
2. Remove the ignition coil from cylinder 4.
3. Use a multimeter to test the primary and secondary resistance of the coil; compare with manufacturer specifications.
4. If it fails the test, replace the ignition coil with a new part.
5. Reinstall the ignition coil and reconnect the connector.

4. Inspect and Clean Fuel Injector

1. Remove the fuel rail from the engine (ensure fuel pressure is relieved before doing this).
2. Take out the fuel injector for cylinder 4.
3. Inspect the fuel injector for clogs or leaks; clean using a fuel injector cleaning solution if necessary.
4. If the injector is faulty, replace it with a new one.
5. Reinstall the fuel injector and the fuel rail, ensuring all connections are secure.

5. Perform Compression Test

1. Remove the spark plug from cylinder 4.
2. Insert a compression tester into the spark plug hole.
3. Crank the engine and read the compression levels; they should be within specifications (typically around 180 psi).
4. If compression is low, further disassembly may be required to inspect internal engine components.