how to fix P0301 misfire code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before starting work.

2. Replace Spark Plug

• Sub-steps:
  1. Remove the engine cover (if applicable) using a socket set.
  2. Unplug the ignition coil connector.
  3. Remove the ignition coil from cylinder 1 by unscrewing the retaining bolt.
  4. Remove the old spark plug using a spark plug socket and ratchet.
  5. Inspect the spark plug for damage; replace it with a new, manufacturer-recommended spark plug.
  6. Reinstall the ignition coil and reconnect the electrical connector.
• Tools Required: Socket set, spark plug socket, ratchet, torque wrench.
• Safety Warnings: Ensure the engine is cool to avoid burns.

3. Replace Ignition Coil (if necessary)

• Sub-steps:
  1. If the ignition coil shows signs of wear or damage, replace it with a new one.
  2. Install the new ignition coil in cylinder 1.
  3. Secure it with the retaining bolt and reconnect the electrical connector.
• Tools Required: Socket set, torque wrench.
• Safety Warnings: Ensure the battery is disconnected during replacement.

4. Inspect/Replace Fuel Injector

• Sub-steps:
  1. Remove the fuel rail (if required) by unscrewing the retaining bolts.
  2. Disconnect the fuel injector connector for cylinder 1.
  3. Remove the fuel injector using a fuel injector puller.
  4. Inspect the injector for clogs; clean or replace if necessary.
  5. Reassemble the fuel rail and reconnect the injector.
• Tools Required: Fuel injector puller, socket set.
• Safety Warnings: Relieve fuel system pressure before starting.

5. Check for Vacuum Leaks

• Sub-steps:
  1. Visually inspect the intake manifold gaskets and vacuum lines for signs of damage or wear.
  2. Use a smoke machine or carburetor cleaner to check for leaks around the intake manifold and vacuum lines.
  3. Repair or replace any damaged components as needed.
• Tools Required: Smoke machine or carburetor cleaner, inspection tools.
• Safety Warnings: Ensure the engine is off and cool when inspecting vacuum lines.