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

Solution

1. Preparation

• Tools Required: OBD-II scanner, torque wrench, spark plug socket, fuel pressure gauge, multimeter
• Disconnect the battery to ensure safety while working on electrical components.
• Allow the engine to cool before beginning any repairs.

2. Inspect and Replace Spark Plugs

• Remove the ignition coils using a socket wrench.
• Pull out the spark plugs with a spark plug socket.
• Inspect the spark plugs for carbon buildup or wear. Replace them with OEM parts if damaged.
• Torque the new spark plugs to manufacturer specifications (typically around 13-15 lb-ft).

3. Test and Replace Ignition Coils

• Use a multimeter to test the resistance of each ignition coil.
• Replace any faulty ignition coils with new ones, ensuring they are compatible with the engine.
• Reinstall the ignition coils and ensure they are seated properly.

4. Fuel Pressure Test

• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (without starting the engine) to check for fuel pressure; it should meet manufacturer specifications (typically around 50-60 psi).
• If the pressure is low, check the fuel pump and filter for issues and replace them as necessary.

5. Inspect Air Intake and Vacuum Lines

• Visually inspect the air intake duct and connections for any cracks or leaks.
• Use a smoke machine or soapy water method to check for vacuum leaks around hoses and gaskets.
• Replace any damaged vacuum lines or gaskets.