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

Solution

1. Preparation

• Gather tools and necessary parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool down.

2. Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket.
• Remove the ignition coils by unbolting and disconnecting the wiring harness.
• Use a spark plug socket to remove the old spark plugs. Inspect for signs of wear or carbon buildup.
• Insert new spark plugs, ensuring they are properly gapped according to manufacturer specifications (usually around 0.043 inches).
• Torque the spark plugs to the specified value (typically around 13 lb-ft).

3. Examine and Replace Ignition Coils

• Tools Required: Socket set, torque wrench.
• If any ignition coils showed signs of damage during inspection, replace them.
• Remove the faulty ignition coil(s) by unscrewing and disconnecting the wiring harness.
• Install new ignition coil(s) and secure them in place.
• Torque the ignition coil bolts to manufacturer specifications.

4. Inspect Fuel Injectors

• Tools Required: Fuel pressure gauge, injector cleaning kit (if needed).
• Check the fuel injector connections and wiring for damage.
• If performance is still lacking, consider removing the injectors for cleaning or replacement.
• Reinstall and ensure all connections are secure.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner.
• Use a smoke machine to check for vacuum leaks around the intake manifold.
• Alternatively, spray carburetor cleaner around suspected areas while the engine is running and listen for RPM changes.
• Repair any identified leaks by replacing gaskets or hoses.