how to fix check engine light code P0301 in my Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, fuel pressure gauge.
• Ensure the vehicle is parked on a flat surface, engage the parking brake, and disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Remove the ignition coil from cylinder 1:
  • Unplug the electrical connector.
  • Remove the mounting bolts using a socket set.
• Remove the spark plug:
  • Use a spark plug socket to carefully unscrew and extract the spark plug.
• Inspect the spark plug for wear or carbon buildup; replace if necessary:
  • Gap the new spark plug to the manufacturer’s specification (typically found in the owner's manual).
• Reinstall the new spark plug:
  • Hand-thread it into the cylinder head and torque it to the manufacturer’s specification (usually around 13-16 lb-ft).

3. Inspect and Replace Ignition Coil

• If the spark plug is in good condition but the misfire persists, remove and inspect the ignition coil:
  • If damaged, replace the ignition coil for cylinder 1 with a new one.
• Reinstall the ignition coil:
  • Secure it with the mounting bolts and reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Remove the fuel rail to access the fuel injector for cylinder 1:
  • Disconnect the fuel line and electrical connector from the injector.
  • Unbolt the fuel rail and lift it away gently.
• Clean or replace the fuel injector:
  • If cleaning, use a fuel injector cleaning kit; if replacing, install the new injector and ensure it is seated properly.
• Reinstall the fuel rail and reconnect all components.

5. Verify Engine Health

• Perform a compression test on cylinder 1:
  • If the compression is low, further diagnosis is required to check for internal engine issues (e.g., valve problems, piston ring wear).

6. Clear Codes and Test Drive

• Reconnect the battery and use the OBD-II scanner to clear the trouble codes.
• Test drive the vehicle to ensure that the check engine light does not reappear.