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

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to avoid electrical shorts.

2. Inspect and Replace Spark Plugs

• Remove the ignition coil or spark plug wires to access the spark plugs.
• Use a spark plug socket and ratchet to remove each spark plug.
• Inspect each spark plug for wear or fouling. Replace with OEM or equivalent spark plugs if necessary.
  • Torque new spark plugs to the manufacturer's specification (typically around 13 ft-lbs).

3. Check and Replace Ignition Coils

• Inspect the ignition coils for cracks or signs of wear.
• If any coils are found defective, remove the faulty ignition coil using a socket set.
• Install new ignition coils, ensuring they are seated properly.
  • Torque bolts as per manufacturer's specification.

4. Inspect and Clean Fuel Injectors

• If fuel injectors are suspected to be clogged, remove them from the intake manifold.
• Use an ultrasonic cleaner or fuel injector cleaner to clean the injectors thoroughly.
• Reinstall cleaned or replaced fuel injectors, ensuring O-rings are lubricated and seated correctly.

5. Verify Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position without starting the engine and check the pressure reading.
• Ensure the fuel pressure is within factory specifications (usually around 40-50 psi). Replace the fuel pump if pressure is low.

6. Inspect Vacuum Hoses

• Check all vacuum hoses for cracks, breaks, or disconnections.
• Replace any damaged hoses to ensure proper air intake and fuel mixture.