how to fix the P0301 misfire code on my Honda Civic 11th Generation (2022-Present)

Solution

1. Preparation

• Gather tools and parts: OBD-II scanner, socket set, torque wrench, multimeter, spark plug socket, compression gauge, cleaning solvent, and new spark plug and ignition coil (if needed).
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plug

• Remove Engine Cover: Use a socket set to remove bolts securing the engine cover and set it aside.
• Remove Spark Plug: Use a spark plug socket and ratchet to carefully unscrew and remove the spark plug from cylinder 1.
• Inspect Spark Plug: Check for signs of wear, fouling, or damage. Replace if necessary.
• Install New Spark Plug: Apply anti-seize compound to the threads of the new spark plug, then hand-tighten and torque to the manufacturer's specification (typically around 13-16 lb-ft).

3. Test and Replace Ignition Coil

• Disconnect Ignition Coil Connector: Unplug the connector from the ignition coil on cylinder 1.
• Remove Ignition Coil: Unscrew the bolts securing the ignition coil and gently pull it out.
• Test Ignition Coil: Use a multimeter to check the resistance of the ignition coil (refer to the service manual for specific values).
• Install New Ignition Coil: If faulty, install the new ignition coil, securing it with bolts and reconnecting the electrical connector.

4. Perform Compression Test

• Remove Fuel Pump Relay: This prevents fuel delivery during the test.
• Attach Compression Gauge: Screw the compression gauge into the spark plug hole of cylinder 1.
• Crank Engine: Crank the engine several times and record the compression reading. Compare to manufacturer specifications.
• Reinstall Spark Plug and Relay: If compression is low, further investigation into engine internals may be required.

5. Inspect and Clean Fuel Injector

• Remove Fuel Injector Connector: Unplug the connector for the fuel injector on cylinder 1.
• Remove Fuel Injector: Unscrew mounting bolts and gently pull out the injector.
• Clean or Replace Injector: If dirty, clean with a suitable solvent; otherwise, replace with a new injector.
• Reinstall Fuel Injector: Ensure proper seating and reconnect the electrical connector.