how to fix P0300 code on Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, spark plug gap tool, torque wrench.
• Remove the ignition coil by unbolting and disconnecting the electrical connector.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear; replace if necessary.
• Gap the new spark plug to the manufacturer specification (usually around 0.043 inches for Toyota).
• Reinstall the spark plug and ignition coil, torquing to manufacturer specifications (typically 13 lb-ft).

3. Check and Replace Ignition Coils

• Tools Required: Socket set, multimeter (for testing).
• Disconnect the negative battery cable.
• Remove the ignition coil from the cylinder head.
• Test the ignition coil with a multimeter to ensure it is within specs (usually 0.5 to 1.5 ohms).
• If defective, replace with a new ignition coil.
• Reconnect the ignition coil and reconnect the battery cable.

4. Examine and Clean Fuel Injectors

• Tools Required: Fuel injector cleaning kit, fuel line disconnect tool.
• Disconnect the fuel lines and remove the fuel injectors from the fuel rail.
• Clean the injectors using a fuel injector cleaning kit.
• Inspect O-rings for wear and replace if necessary.
• Reinstall fuel injectors and reconnect fuel lines.

5. Check for Vacuum Leaks

• Inspect all vacuum hoses for cracks or disconnections.
• Use a smoke machine or carburetor cleaner to identify leaks.
• Replace any damaged hoses or components.

6. Test Engine Compression

• Tools Required: Compression tester.
• Remove spark plugs and insert the compression tester into the spark plug hole.
• Crank the engine and note the compression readings.
• Compare the results against the manufacturer’s specifications (usually 150-200 psi).
• If compression is low, further investigation is needed for possible internal engine issues.