how to fix P0300 code in my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the engine cover if applicable.
• Use the spark plug socket to remove each spark plug.
• Inspect the spark plugs for wear; replace if the electrode is worn or if there is significant carbon buildup.
• Install new spark plugs, torquing them to the manufacturer’s specifications (typically around 13-15 lb-ft for most Toyota plugs).

3. Check and Replace Ignition Coils

• Tools Required: Socket set, multimeter.
• Remove the ignition coil cover if necessary.
• Disconnect the wiring harness from each ignition coil.
• Remove ignition coils using the socket set.
• Test each coil with a multimeter for proper resistance (manufacturer specifications typically range from 0.4 to 0.9 ohms).
• Replace any faulty coils with new ones, ensuring proper seating.

4. Inspect Fuel System

• Tools Required: Fuel pressure gauge, basic hand tools.
• Locate the fuel rail and connect the fuel pressure gauge.
• Turn the ignition to the ON position (do not start the engine) to check fuel pressure; ensure it meets manufacturer specifications (usually around 30-50 psi).
• Inspect fuel injectors visually for leaks and perform a spray pattern test if needed.
• Replace any faulty injectors with new components.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or spray bottle with soapy water.
• Inspect vacuum lines visually for cracks or disconnections.
• Use a smoke machine or spray soapy water around intake gaskets and vacuum lines to identify leaks.
• Repair any leaks found by replacing damaged hoses or gaskets.