how can I fix the P0301 misfire code on my Honda Civic 9th Generation (2012-2015)?

Solution

1. Preparation

• Gather tools: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, fuel injector cleaner.
• Disconnect the negative battery terminal to ensure safety.

2. Replace Spark Plug

• Remove Engine Cover (if applicable):
  • Use a socket set to remove any bolts securing the engine cover.
• Remove Spark Plug:
  • Use a spark plug socket and ratchet to carefully unscrew and remove the spark plug from cylinder 1.
• Install New Spark Plug:
  • Ensure the new spark plug is gapped correctly (refer to specifications).
  • Hand-tighten the spark plug, then use a torque wrench to tighten to the manufacturer's specification (typically 13 lb-ft for Honda).

3. Check and Replace Ignition Coil

• Remove Ignition Coil:
  • Unplug the electrical connector from the ignition coil.
  • Remove the bolts securing the ignition coil and lift it out.
• Install New Ignition Coil:
  • Place the new ignition coil in position and secure it with bolts.
  • Reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Access Fuel Injector:
  • Remove the intake manifold if necessary to access the fuel injector for cylinder 1.
• Clean or Replace Fuel Injector:
  • Use fuel injector cleaner to clean the injector or replace it with a new one if cleaning does not resolve the issue.
• Reassemble Components:
  • Reinstall any components removed to access the fuel injector, ensuring all connections are secure.

5. Perform Compression Test

• Test Compression:
  • Remove the spark plug from cylinder 1 again.
  • Insert the compression tester into the spark plug hole and crank the engine.
  • Record the compression reading. It should be within the manufacturer's specifications (usually around 190 psi).

6. Reassemble and Reconnect

• Reinstall the intake manifold and engine cover if removed.
• Reconnect the negative battery terminal.