how to fix P0300 misfire code on Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool if it has been running.

2. Inspect and Replace Spark Plugs

• Sub-steps:

  1. Remove the engine cover (if applicable) using a socket set.
  2. Disconnect ignition coils from the spark plugs.
  3. Remove spark plugs using a spark plug socket and ratchet.
  4. Inspect the spark plugs for damage, wear, or excessive carbon buildup.
  5. Replace spark plugs with new ones, ensuring the gap is set to manufacturer specifications (usually around 0.043 inches).

• Tools Required: Spark plug socket, ratchet, torque wrench.

3. Inspect and Replace Ignition Coils

• Sub-steps:

  1. Remove the ignition coils from the spark plugs.
  2. Visually inspect the coils for cracks or carbon tracking.
  3. Test the coils using a multimeter to verify resistance (check specifications).
  4. Replace any faulty ignition coils with new ones.
  5. Reinstall the ignition coils onto the new spark plugs.

• Tools Required: Multimeter, socket set.

4. Clean or Replace Fuel Injectors

• Sub-steps:

  1. Disconnect fuel injector connectors.
  2. Remove the fuel rail (if necessary) to access the injectors.
  3. Clean injectors using a fuel injector cleaning kit or replace them if they are clogged or defective.
  4. Reinstall fuel rail and reconnect all connectors.

• Tools Required: Fuel injector cleaning kit or replacement injectors, socket set.

5. Conduct Compression Test

• Sub-steps:

  1. Remove spark plugs to allow access.
  2. Insert the compression tester into each cylinder's spark plug hole.
  3. Crank the engine and record the compression readings.
  4. Compare the readings against manufacturer specifications to identify any mechanical issues.

• Tools Required: Compression tester.