how to fix P0304 code in Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather tools and parts required.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Replace Spark Plug

• Remove the ignition coil for cylinder 4:
  • Unplug the electrical connector.
  • Remove the retaining bolts using a socket set.
• Extract the spark plug using a spark plug socket.
• Inspect the spark plug for wear or carbon buildup; replace if necessary.
• Install the new spark plug to the specified torque (typically 13 lb-ft).

3. Check and Replace Ignition Coil

• If the spark plug is in good condition, visually inspect the ignition coil:
  • Check for cracks or carbon tracking.
• If damaged, replace the ignition coil:
  • Install the new ignition coil and secure it using the retaining bolts.
  • Reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Remove the fuel rail to access the injector for cylinder 4:
  • Relieve fuel pressure by removing the fuel pump fuse and running the engine until it stalls.
  • Disconnect the fuel lines using a fuel line disconnect tool.
• Remove the injector and inspect it for clogging or damage.
• Clean or replace the injector as necessary, ensuring proper seating during reinstallation.

5. Verify Engine Compression

• Conduct a compression test on cylinder 4:
  • Remove the spark plug and screw in the compression tester.
  • Crank the engine and record the compression value; it should be within manufacturer specifications (typically around 190 psi).
• If the compression is low, further investigation into the engine internals may be necessary.