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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, fuel pressure gauge, multimeter.
• Disconnect the negative battery terminal to ensure safety.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the ignition coil cover if applicable.
  2. Unplug the ignition coils from the spark plugs.
  3. Use a socket wrench to remove the spark plugs.
  4. Inspect the old spark plugs for wear, carbon buildup, or damage.
  5. Install new spark plugs, tightening to the manufacturer's specified torque (typically around 13-15 lb-ft).
  6. Reconnect the ignition coils.

3. Check and Replace Ignition Coils

• Sub-steps:
  1. Test each ignition coil using a multimeter to check for proper resistance.
  2. If a coil is out of specification, remove it by unscrewing the mounting bolts and disconnecting the electrical connector.
  3. Install the new ignition coil, ensuring it is secured and connected properly.

4. Fuel System Inspection

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail to check for proper fuel pressure (consult the service manual for specifications).
  2. If pressure is low, inspect the fuel pump and fuel filter for issues.
  3. Replace the fuel filter if necessary and check for proper fuel pump operation.

5. Vacuum Leak Inspection

• Sub-steps:
  1. Visually inspect all vacuum lines for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to detect leaks.
  3. Replace any damaged vacuum lines as needed.