what does it mean if my Toyota Highlander has a check engine light and a P0300 code

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery negative terminal to prevent electrical shorts.

2. Inspect and Replace Spark Plugs

1. Remove the ignition coil cover (if applicable) using a socket set.
2. Remove the spark plugs using a spark plug socket; inspect for wear or fouling.
3. Replace with new spark plugs, ensuring they are gapped correctly according to manufacturer specifications (typically 0.043 inches for many Toyota engines).
4. Reinstall the ignition coils and cover.

3. Test and Replace Ignition Coils (if necessary)

1. Test each ignition coil using a multimeter to check for proper resistance (typically 0.4 - 0.7 ohms for primary and 10 - 15 k ohms for secondary).
2. Replace any faulty ignition coils with new ones, ensuring they match the OEM specifications.
3. Reconnect the electrical connectors firmly.

4. Fuel System Inspection

1. Connect a fuel pressure gauge to the fuel rail to check for proper fuel pressure (typically around 30-40 psi, depending on the model).
2. If the pressure is low, inspect the fuel filter and replace if clogged.
3. Inspect and clean fuel injectors using a fuel injector cleaning kit or replace them if necessary.

5. Check for Vacuum Leaks

1. Inspect all vacuum hoses and connections for cracks or loose fittings.
2. Use a smoke machine to detect any vacuum leaks around the intake manifold and hoses.
3. Repair or replace any damaged hoses.