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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, fuel injector cleaner.
• Safety Warnings: Ensure the engine is cool before working on ignition components. Disconnect the battery before starting repairs.

2. Replace Spark Plug

• Remove the ignition coil from cylinder 1:
  • Disconnect the electrical connector.
  • Remove the bolts securing the coil.
  • Pull the coil straight out.
• Remove the spark plug:
  • Use a spark plug socket to unscrew the spark plug.
  • Inspect the spark plug for wear or fouling.
• Install the new spark plug:
  • Apply anti-seize compound to the threads if necessary.
  • Torque the spark plug to the manufacturer's specification (typically around 13 lb-ft).

3. Replace Ignition Coil (if necessary)

• If the ignition coil is found to be faulty, replace it:
  • Install the new ignition coil in reverse order of removal.
  • Reconnect the electrical connector and secure the coil with bolts.

4. Clean or Replace Fuel Injector

• If the fuel injector is malfunctioning:
  • Remove the fuel injector from cylinder 1 (ensure fuel pressure is relieved).
  • Clean the injector with an appropriate injector cleaner or replace it with a new one.
• Reinstall the fuel injector and ensure it is seated properly.

5. Check Compression

• If low compression is detected:
  • Determine the cause (valve problems, head gasket failure, etc.) and repair accordingly.