how to fix P0300 code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts.
• Ensure the engine is cool.
• Disconnect the battery to avoid electrical shock.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coils by unscrewing the mounting bolts and disconnecting the electrical connectors.
• Remove the spark plugs using the spark plug socket.
• Inspect the spark plugs for wear; replace if necessary.
• Install new spark plugs, ensuring the correct gap, and torque them to the manufacturer’s specifications (usually around 13-15 lb-ft).
• Reinstall the ignition coils.

3. Check and Replace Ignition Coils (if necessary)

• If any coils were found defective, remove them as previously described.
• Install new ignition coils, ensuring they are seated properly.
• Reconnect the electrical connectors.

4. Fuel Injector Inspection

• Tools Required: Noid light or multimeter.
• Disconnect the fuel injectors and check for proper voltage signal.
• If injectors are faulty, remove them from the fuel rail and replace with new ones.
• Reinstall the fuel injectors ensuring proper seating and connection.

5. Vacuum Leak Inspection

• Visually inspect all vacuum lines for cracks or disconnections.
• Use a smoke machine to identify leaks in the intake system.
• Replace any damaged lines or seals as necessary.

6. Compression Test

• Tools Required: Compression gauge.
• Remove the spark plugs and attach the compression gauge to each cylinder.
• Crank the engine to get the compression reading; compare results with manufacturer specifications.
• If readings are low, further investigation may be needed for internal engine issues.