what does it mean when my Honda Accord has a P0304 code

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 for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Remove the ignition coil and spark plug from cylinder 4.
• Inspect the spark plug for wear, carbon buildup, or damage.
• If worn, replace with a new spark plug (refer to OEM specifications for part number).
• Torque the new spark plug to the manufacturer’s specifications (typically around 13-15 lb-ft).

3. Check and Replace Ignition Coil (if necessary)

• Test the ignition coil for proper resistance using a multimeter.
• If the coil is faulty, remove it from the cylinder head.
• Install a new ignition coil, ensuring it is seated properly and connected.

4. Inspect and Clean Fuel Injector

• Disconnect the fuel injector connector and remove the injector from cylinder 4.
• Inspect the injector for clogs or damage.
• Use a fuel injector cleaner to clean the injector or replace it if necessary.

5. Perform Compression Test

• Insert a compression gauge into cylinder 4.
• Crank the engine a few times and note the reading; it should be within the manufacturer’s specified range.
• If the compression is low, further investigate valve seals or piston rings.

6. Check for Vacuum Leaks

• Inspect hoses and the intake manifold for cracks or loose connections.
• Use a smoke machine or soapy water to identify leaks; repair as necessary.