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

Solution

1. Preparation

• Gather 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.
  2. Disconnect the ignition coils from the spark plugs.
  3. Remove the spark plugs using a spark plug socket and ratchet.
  4. Inspect the spark plugs for wear and carbon buildup. Replace with OEM specifications (typically Denso or NGK).
• Tools Required: Spark plug socket, ratchet, torque wrench.

3. Inspect and Replace Ignition Coils

• Sub-steps:
  1. If spark plugs are in good condition, move to the ignition coils.
  2. Remove the bolts securing the ignition coils and lift them out of the cylinder head.
  3. Inspect for cracks or signs of failure. Replace with OEM parts if any issues are found.
• Tools Required: Ratchet, socket set.

4. Check Fuel System

• Sub-steps:
  1. Use a fuel pressure gauge to check the fuel pressure at the fuel rail.
  2. If pressure is low, inspect the fuel pump and filter for issues.
  3. Clean or replace fuel injectors if they are clogged.
• Tools Required: Fuel pressure gauge, injector cleaning kit.

5. Inspect Air Intake and Vacuum Lines

• Sub-steps:
  1. Remove the air intake duct and inspect for blockages or leaks.
  2. Check the MAF sensor for cleanliness; clean with MAF cleaner if necessary.
  3. Inspect and replace any damaged vacuum lines.
• Tools Required: Screwdrivers, MAF cleaner.