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

Solution

1. Preparation

• Gather tools and materials needed for repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Spark Plugs

• Remove the engine cover (if applicable) using a socket set.
• Disconnect ignition coils from each spark plug.
• Remove spark plugs using a spark plug socket.
• Inspect spark plugs for wear; replace them if they are fouled or worn (use OEM-recommended spark plugs).
• Torque new spark plugs to the manufacturer’s specifications (typically around 13-15 lb-ft).

3. Check and Replace Ignition Coils

• With spark plugs removed, inspect ignition coils for any damage or signs of wear.
• If any coil shows damage, remove it by unscrewing the mounting bolts and disconnecting the electrical connector.
• Install the new ignition coil and ensure it is properly seated and connected.
• Repeat for all affected cylinders if necessary.

4. Examine Fuel System

• Connect a fuel pressure gauge to the fuel rail and turn the ignition to the "On" position without starting the engine to check fuel pressure.
• If pressure is below specifications (usually around 50-60 psi), inspect the fuel pump and filter. Replace any faulty components as needed.

5. Inspect for Vacuum Leaks

• Visually inspect all vacuum hoses and the intake manifold for cracks or disconnections.
• Use a smoke machine if available to detect any elusive leaks.
• Repair or replace any damaged hoses or gaskets.

6. Reconnect Battery and Clear Codes

• Reconnect the battery terminals securely.
• Use the OBD-II scanner to clear any stored codes and reset the check engine light.