how to fix the P0301 misfire code on my Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather tools and parts needed for repairs.
• Disconnect the negative terminal of the battery to prevent electrical shorts.
• Allow the engine to cool down before beginning work.

2. 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 using a spark plug socket:
  • Inspect the old spark plug for wear, carbon buildup, or damage.
  • Gap the new spark plug according to manufacturer specifications (typically 0.043 inches for Toyota).
• Install the new spark plug:
  • Torque to manufacturer specifications (typically 13 lb-ft).
• Reinstall the ignition coil, securing it with bolts and reconnecting the electrical connector.

3. Replace Ignition Coil (if necessary)

• If the ignition coil showed signs of damage during inspection, replace it:
  • Remove the faulty ignition coil as in step 2.
  • Install the new ignition coil and secure it with bolts.
  • Reconnect the electrical connector.

4. Inspect and Clean Fuel Injector

• Remove the fuel rail if necessary to access the injector:
  • Disconnect the fuel line using a fuel line tool.
  • Unbolt the fuel rail and gently pull it off.
• Remove the fuel injector from cylinder 1:
  • Check O-rings for damage and replace if necessary.
  • Clean the injector using a fuel injector cleaner or ultrasonic cleaner.
• Reinstall the injector and fuel rail, ensuring proper seating of O-rings.

5. Check and Repair Vacuum Leaks

• Inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
• Replace any damaged hoses and ensure all connections are secure.

6. Verify Engine Compression (if necessary)

• If previous steps did not resolve the misfire, perform a compression test:
  • Remove the spark plug for cylinder 1.
  • Insert a compression gauge and crank the engine to get a reading.
  • Compare results to manufacturer specifications; low compression may indicate internal engine issues.