why does my Toyota Corolla E140 (2006-2013) have a check engine light with code P0300

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plugs

• Remove the ignition coils from the spark plugs.
• Use a spark plug socket to remove the spark plugs.
• Inspect the spark plugs for wear, carbon deposits, or damage. Replace if necessary.
• Install new spark plugs, ensuring the correct gap is set (typically 0.043 inches for the Corolla).
• Torque the spark plugs to the manufacturer's specifications (typically around 13 lb-ft).

3. Check and Replace Ignition Coils (if necessary)

• If the spark plugs are in good condition, test the ignition coils using a multimeter.
• Replace any faulty ignition coils with new ones, ensuring they match the specifications for the vehicle.
• Reinstall the ignition coils securely.

4. Fuel System Inspection

• Connect a fuel pressure gauge to the fuel rail and turn the ignition to the "ON" position without starting the engine.
• Check for proper fuel pressure (typically around 43-50 psi).
• If pressure is low, inspect the fuel filter and fuel pump for issues and replace as needed.

5. Air Intake and Exhaust Inspection

• Inspect the air filter and air intake duct for obstructions. Replace the air filter if it is dirty.
• Check for any vacuum leaks around hoses and gaskets.
• Inspect the exhaust system for blockages, particularly the catalytic converter. If blockage is suspected, perform a backpressure test.