how to fix P0304 code on Honda Accord 9th Generation (2013-2017)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Honda Accord 9th Generation. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery for safety.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Spark Plug

• Tools Required: Spark plug socket, ratchet, torque wrench
• Remove the engine cover if applicable.
• Locate and remove the spark plug for cylinder 4 using the spark plug socket.
• Inspect the spark plug for wear (burnt electrode, carbon fouling). Replace with a new spark plug if necessary, using the manufacturer's specifications for gap and torque (typically around 13 lb-ft).

3. Check and Replace Ignition Coil

• Tools Required: Ratchet, socket set
• Locate the ignition coil for cylinder 4.
• Disconnect the electrical connector carefully.
• Remove the ignition coil bolt and take out the coil.
• Inspect the coil for cracks or damage; replace it if faulty.
• Reinstall the new ignition coil, securing it with the bolt and reconnecting the electrical connector.

4. Inspect and Replace Fuel Injector (if necessary)

• Tools Required: Fuel injector removal tool, ratchet, socket set
• Locate the fuel injector for cylinder 4.
• Disconnect the electrical connector and fuel line (be cautious of fuel spray).
• Remove the fuel injector retaining clip and pull the injector out.
• Inspect the injector for clogs; replace it if necessary with a new one.
• Reinstall the injector, ensuring it seats properly and secure the fuel line and connector.

5. Perform Compression Test (if previous steps do not resolve issue)

• Tools Required: Compression tester
• Remove the spark plug for cylinder 4.
• Install the compression tester and crank the engine.
• Record the compression reading; it should be within the manufacturer’s specified range (typically 160-200 psi).
• If compression is low, further investigation into engine internals may be necessary.