how to fix Honda Civic 9th Generation (2012-2015) misfire issue and code P0301?

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter.
• Safety Warnings: Disconnect the battery before working on electrical systems.

2. Replace Spark Plug

• Remove the engine cover if applicable.
• Disconnect the ignition coil connector from cylinder 1.
• Use a socket wrench to remove the ignition coil from cylinder 1.
• Remove the spark plug using a spark plug socket.
• Install the new spark plug by hand to avoid cross-threading, then torque to the manufacturer’s specification (typically around 13 lb-ft).
• Reinstall the ignition coil and reconnect the spark plug connector.

3. Test and Replace Ignition Coil (if necessary)

• Use a multimeter to check the resistance of the ignition coil. Compare the readings to the specifications in the service manual.
• If the coil is faulty, replace it with a new one:
  • Unplug the ignition coil connector.
  • Remove the ignition coil.
  • Install the new ignition coil and reconnect the connector.

4. Inspect and Test Fuel Injector

• Disconnect the fuel injector connector for cylinder 1.
• Use a multimeter to check the resistance of the fuel injector.
• If the injector is faulty, replace it by:
  • Removing the fuel rail if necessary.
  • Pulling out the old injector and inserting the new one, ensuring it is properly seated.
  • Reconnect the fuel injector connector.

5. Compression Test (if misfire persists)

• Remove the spark plug from cylinder 1.
• Insert the compression tester into the spark plug hole.
• Crank the engine a few times and record the compression reading.
• Compare it to the manufacturer's specifications. If low, further diagnosis is needed for potential internal engine issues.