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

Solution

1. Preparation

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

2. Inspect and Replace Spark Plugs

• Remove the ignition coil cover or engine cover if necessary.
• Using a socket wrench, remove the spark plugs.
• Inspect the spark plugs for signs of wear (e.g., fouling, excessive gap).
• Replace worn spark plugs with OEM or equivalent parts (typically NGK or Denso for Toyota).
• Torque the new spark plugs to manufacturer specifications (usually around 13 ft-lbs).

3. Check and Replace Ignition Coils

• Visually inspect ignition coils for cracks or damage.
• Remove the ignition coils by unscrewing them from the cylinder head.
• Test ignition coils with a multimeter to ensure they are within specification (consult service manual for values).
• Replace any faulty ignition coils with OEM parts.
• Reinstall the ignition coils and ensure they are seated properly.

4. Inspect Fuel System

• Check the fuel filter for clogs; replace if necessary.
• Test fuel pressure using a fuel pressure gauge to ensure it meets specifications (typically around 43-50 psi).
• Inspect fuel injectors for clogs or leaks; clean or replace as necessary.

5. Address Vacuum Leaks

• Inspect all vacuum hoses for signs of wear or damage.
• Replace any cracked or disconnected hoses.
• Use a smoke test to identify any hidden vacuum leaks.

6. Perform Compression Test

• Remove all spark plugs and disable the fuel system.
• Use a compression gauge to test each cylinder's compression.
• Compare readings against manufacturer specifications (usually around 180-200 psi).
• Address any cylinders with significantly lower readings, which may indicate mechanical issues (e.g., worn piston rings, valve issues).