how to fix P0300 code in Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface with the engine off.
• Disconnect the negative battery terminal for safety.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, dielectric grease.
• Remove the engine cover (if applicable).
• Disconnect the ignition coil connectors and remove the ignition coils.
• Take out the spark plugs using a spark plug socket.
• Inspect the spark plugs for wear and carbon build-up; replace if necessary.
• Apply a small amount of dielectric grease to the ignition coil boots.
• Reinstall the spark plugs and ignition coils, ensuring they are torqued to the manufacturer’s specifications (typically 13-15 ft-lbs).

3. Inspect and Replace Ignition Coils

• If misfires persist after replacing spark plugs, inspect ignition coils.
• Swap the suspected faulty ignition coil with a known good one from another cylinder to confirm the issue.
• Replace any faulty ignition coils with OEM parts.

4. Check Fuel Injectors

• Inspect fuel injectors for proper operation.
• Clean or replace fuel injectors as necessary.
• Verify fuel injector connections are secure.

5. Repair Vacuum Leaks

• Inspect hoses, gaskets, and intake manifold for leaks.
• Replace any damaged hoses or gaskets identified during inspection.

6. Clear Codes and Test Drive

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the trouble codes.
• Perform a test drive to ensure the issue is resolved.