my Toyota Highlander Third Generation (2014-2019) has a check engine light with P0300 code

Solution

1. Preparation

• Gather tools and parts required for repair.
• Disconnect the negative battery terminal to prevent electrical short circuits.
• Allow the engine to cool down before working on components.

2. Replace Spark Plugs

• Remove the engine cover (if applicable) using a socket set.
• Unscrew and remove the old spark plugs using a spark plug socket.
• Inspect the spark plug gap and condition, replace with new spark plugs if necessary.
• Torque new spark plugs to manufacturer specifications (typically around 13-15 lb-ft).

3. Inspect and Replace Ignition Coils

• Disconnect the electrical connectors from the ignition coils.
• Remove the bolts securing the ignition coils using a socket set.
• Carefully pull out the ignition coils and inspect for wear or damage.
• Replace any faulty ignition coils with new ones and secure them with bolts to manufacturer torque specifications.

4. Clean or Replace Fuel Injectors

• If injectors are clogged, use a fuel injector cleaner or replace them if necessary.
• Remove fuel injector clips and disconnect the fuel lines (ensure fuel pressure is relieved beforehand).
• Replace with new injectors and ensure they are seated properly.

5. Check for Vacuum Leaks

• Inspect all vacuum hoses for cracks or disconnections.
• If any leaks are found, replace the affected hoses.
• Use a smoke machine or carburetor cleaner to identify any additional leaks in the intake manifold.