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

Solution

1. Preparation

• Gather tools and components.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before starting work.

2. Inspect and Replace Spark Plugs

• Remove the ignition coils by unscrewing them and pulling them out.
• Use a spark plug socket to remove the spark plugs.
• Inspect the spark plugs for wear; replace any that are worn or fouled.
• Install new spark plugs with a torque of 13 ft-lbs.

3. Test and Replace Ignition Coils

• Use a multimeter to measure the resistance of each ignition coil.
• If any coil is out of specification, remove it and replace it with a new one.
• Reinstall the ignition coils securely.

4. Clean or Replace Fuel Injectors

• If fuel injectors are suspected to be clogged, use a fuel injector cleaning kit.
• If cleaning is ineffective, remove and replace the fuel injectors with new ones.
• Follow the manufacturer's specifications for installation.

5. Inspect Vacuum Hoses

• Visually check all vacuum hoses for cracks or disconnections.
• Replace any damaged hoses with OEM parts to prevent vacuum leaks.

6. Check Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition on without starting the engine and check the pressure.
• Compare the reading with the manufacturer’s specifications; replace the fuel pump if out of range.