how to fix P0304 misfire code in Honda Accord Eleventh Generation (2023-present)

Learn how to diagnose and fix P0304 cylinder 4 misfire in Honda Accord. 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 while working.
• Allow the engine to cool before proceeding.

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench, gap gauge.
• Remove the ignition coil cover (if applicable).
• Disconnect the ignition coil connector and remove the ignition coil from cylinder 4.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear or damage, and replace if necessary.
• Set the gap on the new spark plug to manufacturer specifications (typically 0.043 inches).
• Install the new spark plug and torque to the manufacturer's specifications (usually 13 lb-ft).

3. Check and Replace Ignition Coil

• If the spark plug is fine, inspect the ignition coil.
• Tools Required: Socket set.
• Remove the ignition coil from cylinder 4.
• Test the ignition coil with a multimeter to ensure it meets resistance specifications.
• Replace the ignition coil if it is faulty.
• Reinstall the ignition coil and reconnect the connector.

4. Inspect and Replace Fuel Injector

• If ignition components are functioning correctly, test the fuel injector.
• Tools Required: Fuel pressure gauge, socket set.
• Remove the fuel injector connector and use a multimeter to check for voltage.
• If voltage is present, remove the fuel injector.
• Inspect for clogs or damage and replace if necessary.
• Reinstall the fuel injector and reconnect the electrical connector.

5. Perform Compression Test

• If the issue persists, perform a compression test on cylinder 4.
• Tools Required: Compression tester.
• Remove the spark plug from cylinder 4.
• Insert the compression tester into the spark plug hole and crank the engine.
• Record the compression reading; it should be within manufacturer specifications (usually around 180 psi).
• If compression is low, inspect for possible internal engine issues such as valve problems or head gasket failure.