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

Solution

1. Preparation

• Tools Required:
  • OBD-II scanner
  • Socket set
  • Torque wrench
  • Fuel pressure gauge
  • Multimeter
• Ensure the vehicle is parked on a level surface and the ignition is off. Disconnect the battery prior to starting work.

2. Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover (if necessary) by unscrewing bolts.
  2. Disconnect the ignition coils from the spark plugs.
  3. Use a spark plug socket to remove old spark plugs.
  4. Inspect the old plugs; if they are fouled or damaged, replace them with OEM equivalent plugs.
  5. Gap the new spark plugs according to manufacturer specifications.
  6. Install the new spark plugs and torque to the manufacturer's specifications (typically around 13 lb-ft).
  7. Reconnect the ignition coils.

3. Inspect and Replace Ignition Coils

• Sub-steps:
  1. Test each ignition coil with a multimeter to check for resistance (refer to service manual for specifications).
  2. If any coils fail the test, remove the faulty ignition coils using a socket set.
  3. Install new ignition coils, ensuring they are seated correctly.
  4. Reconnect all wiring harnesses.

4. Check and Clean Fuel Injectors

• Sub-steps:
  1. Remove the fuel rail assembly to access the fuel injectors.
  2. Inspect the fuel injectors for clogs and clean them using a fuel injector cleaner or replace them if necessary.
  3. Reinstall the fuel rail assembly, ensuring proper sealing and torque specifications are followed.

5. Test Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail test port.
  2. Turn the ignition key to the "ON" position without starting the engine to check the fuel pressure reading.
  3. Compare the reading to the manufacturer specifications (typically around 50-60 psi).
  4. If the pressure is low, check the fuel pump and fuel filter for issues.