why does my Toyota Tacoma N300 (2016-Present) have a check engine light and code P0300?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical short circuits.
• Ensure the vehicle is on a level surface and secured with wheel chocks.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover if applicable.
  2. Disconnect the ignition coils from the spark plugs.
  3. Using a spark plug socket, remove the spark plugs.
  4. Inspect the spark plugs for wear; replace if they show signs of fouling or excessive wear.
  5. Install new spark plugs to the manufacturer’s specified torque (typically around 13-15 lb-ft).

3. Check and Replace Ignition Coils

• Sub-steps:
  1. While the spark plugs are removed, inspect the ignition coils for any cracks or damage.
  2. Swap the ignition coils from the misfiring cylinder(s) with those from a known good cylinder to see if the misfire follows the coil.
  3. Replace any faulty ignition coils with new ones, ensuring proper installation.

4. Inspect and Clean Fuel Injectors

• Sub-steps:
  1. Use a fuel injector cleaning kit to clean the injectors if they are clogged.
  2. If cleaning does not resolve the issue, consider replacing faulty fuel injectors with new ones.
  3. Reconnect the fuel injector connectors after servicing.

5. Check for Vacuum Leaks

• Sub-steps:
  1. Inspect all vacuum hoses visually for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner spray to check for vacuum leaks around the intake manifold and hoses.
  3. Replace any damaged hoses or gaskets.

6. Monitor Fuel Pressure

• Sub-steps:
  1. Attach a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position (without starting) and check the pressure reading.
  3. If the pressure is below specifications (refer to the service manual), replace the fuel pump as necessary.