how to fix P0300 misfire code on Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool before working on engine components.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover (if necessary) using a socket set.
  2. Remove the ignition coils by unscrewing the bolts and disconnecting the electrical connectors.
  3. Unscrew the spark plugs using a spark plug socket.
  4. Inspect the spark plugs for wear or damage; replace them if necessary with OEM specified plugs.
  5. Install new spark plugs and torque them to the manufacturer's specifications (typically around 13 ft-lbs).

3. Test and Replace Ignition Coils (if needed)

• Sub-steps:
  1. Test each ignition coil with a multimeter to check for proper resistance. Consult service manual for specific resistance values.
  2. If a coil is faulty, disconnect the electrical connector and remove the coil by unscrewing it.
  3. Install the new ignition coil and reconnect the electrical connector.
  4. Repeat for any other coils diagnosed as faulty.

4. Fuel System Inspection and Repair

• Sub-steps:
  1. Connect the fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "on" position (do not start the engine) and check the fuel pressure against manufacturer specifications (typically 35-50 psi).
  3. If pressure is low, inspect the fuel pump, filter, and lines for blockages or failures.
  4. Replace any faulty components as necessary.

5. Check for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks or disconnections.
  2. Use a smoke machine or spray carburetor cleaner around hoses and intake manifold while the engine is running to detect leaks.
  3. Replace any damaged hoses and ensure all connections are secure.