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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, compression tester, multimeter, fuel injector cleaner.
• Ensure the engine is cool and disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plug

• Sub-steps:
  1. Remove the ignition coil from cylinder 1 by unscrewing the retaining bolts and disconnecting the electrical connector.
  2. Unscrew the spark plug using a spark plug socket.
  3. Inspect the old spark plug for signs of wear or fouling; replace it with a new spark plug with the correct gap (0.043 inches).
  4. Reinstall the spark plug and torque it to the manufacturer’s specification (typically around 13 lb-ft).
  5. Reattach the ignition coil and reconnect the electrical connector.

3. Test Ignition Coil

• Sub-steps:
  1. Using a multimeter, test the primary and secondary resistance of the ignition coil.
  2. If the resistance is out of specification, replace the ignition coil for cylinder 1.
  3. Reconnect the ignition coil and ensure it is secured properly.

4. Compression Test

• Sub-steps:
  1. Remove the spark plug from cylinder 1 to allow access for the compression tester.
  2. Insert the compression tester into the spark plug hole and crank the engine.
  3. Record the compression reading; it should meet manufacturer specifications (typically around 180 psi).
  4. If compression is low, further investigation is needed for potential head gasket failure or valve issues.

5. Clean or Replace Fuel Injector

• Sub-steps:
  1. Disconnect the fuel injector connector and remove the fuel rail assembly if necessary.
  2. Inspect the injector for clogs; clean it using a fuel injector cleaner or replace it if faulty.
  3. Reinstall the injector and reconnect any necessary components.