how to diagnose and fix P0300 code in Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool completely before starting work.

2. Replace Spark Plugs

• Tools Required: Spark plug socket, ratchet, torque wrench, gap tool.
• Remove the ignition coil covers (if applicable) and disconnect the electrical connectors.
• Unscrew and remove the old spark plugs using the spark plug socket.
• Check the gap of the new spark plugs according to the manufacturer's specifications (typically 0.043 inches for Toyota).
• Install the new spark plugs hand-tight, then torque them to the specified value (typically 13 lb-ft).
• Reconnect the ignition coils and covers.

3. Replace Ignition Coils (if necessary)

• Tools Required: Socket set, ratchet, torque wrench.
• Disconnect the electrical connectors from the ignition coils.
• Remove the mounting bolts for the ignition coils and lift them out.
• Install the new ignition coils and secure them with mounting bolts.
• Reconnect the electrical connectors.

4. Inspect and Clean Fuel Injectors

• Tools Required: Fuel injector cleaning kit (if needed), socket set.
• Remove the fuel rail (ensure fuel pressure is relieved prior to this).
• Inspect fuel injectors for clogs or leaks.
• Clean the injectors using a fuel injector cleaning kit or replace them if necessary.
• Reinstall the fuel rail and ensure all connections are secure.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner.
• With the engine running, introduce smoke or spray carburetor cleaner around the intake manifold.
• Listen for changes in engine RPM to identify leaks.
• Repair or replace any damaged gaskets or hoses found.