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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on the engine components.

2. Inspect and Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket
• Remove the ignition coils to access the spark plugs.
• Use a spark plug socket to carefully remove each spark plug.
• Inspect the condition of the spark plugs; replace them if they show signs of wear (e.g., excessive gap, fouling, or corrosion).
• Install new spark plugs (use OEM or equivalent) and torque them to the manufacturer's specification (usually around 13-15 ft-lbs).
• Reinstall the ignition coils securely.

3. Test and Replace Ignition Coils

• Tools Required: Multimeter (if testing), socket set
• If spark plugs are fine, test each ignition coil using a multimeter to ensure they are functioning properly.
• If any ignition coils are faulty, replace them with new ones.
• Reinstall any removed components and reconnect the battery.

4. Inspect Fuel Injectors

• Tools Required: Fuel pressure gauge, socket set
• Check the fuel pressure using a fuel pressure gauge to ensure it meets specifications.
• If pressure is low, inspect the fuel pump and filter.
• Remove the fuel injectors and examine them for clogs; clean or replace as necessary.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner
• Inspect all vacuum lines for cracks or disconnections.
• Use a smoke machine or carburetor cleaner to test for vacuum leaks by spraying around the intake manifold and vacuum lines; listen for changes in engine RPMs.
• Repair or replace any damaged vacuum lines found.