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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shock.

2. Inspect and Replace Spark Plug

• Sub-steps:
  1. Remove the ignition coil from cylinder 1 by unbolting it and disconnecting the electrical connector.
  2. Remove the spark plug using a spark plug socket and ratchet.
  3. Inspect the spark plug for wear, fouling, or damage. Replace with a new spark plug if necessary, ensuring it is gapped to the manufacturer's specifications (typically 0.043 inches for Toyota).
  4. Reinstall the spark plug and torque it to the manufacturer’s specified value (around 13 lb-ft).
  5. Reinstall the ignition coil, reconnect the electrical connector, and secure it in place.

3. Inspect and Replace Ignition Coil

• Sub-steps:
  1. If the spark plug is in good condition, test the ignition coil using a multimeter. Measure the primary and secondary resistance as per specifications.
  2. If the ignition coil tests faulty, replace it with a new coil that matches OEM specifications.
  3. Reinstall the new ignition coil and reconnect the electrical connector.

4. Check Fuel Injector

• Sub-steps:
  1. Disconnect the fuel injector electrical connector.
  2. Use a multimeter to check for proper resistance across the injector terminals (typically around 12-16 ohms).
  3. If faulty, remove the fuel injector by unscrewing the mounting bolts and sliding it out of the rail.
  4. Replace with a new fuel injector and ensure proper seating.
  5. Reconnect the electrical connector.

5. Final Checks

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Start the engine and let it idle to ensure proper operation.
  3. Monitor for any check engine light reappearance and verify smooth engine operation.