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

Solution

1. Preparation

• Gather necessary tools and parts before starting the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Replace Spark Plugs

• Tools Required: Spark plug socket, ratchet, torque wrench.
• Remove the ignition coils by unscrewing the bolts and disconnecting the electrical connectors.
• Using the spark plug socket, carefully unscrew the old spark plugs.
• Inspect the spark plug gaps and replace with new spark plugs to the manufacturer’s specifications.
• Torque the new spark plugs to the manufacturer's specifications (usually around 13-16 ft-lbs).
• Reinstall the ignition coils, ensuring electrical connections are secure.

3. Inspect and Replace Ignition Coils (if necessary)

• Tools Required: Socket set, ratchet, torque wrench.
• If ignition coils are damaged or faulty, remove them as described in the previous step.
• Install new ignition coils, ensuring they are seated properly.
• Torque the mounting bolts as per manufacturer specifications.

4. Clean or Replace Fuel Injectors

• Tools Required: Fuel injector cleaning kit or replacement injectors, appropriate O-rings.
• If injectors are clogged, use a cleaning kit to clean them following the manufacturer’s instructions.
• If replacement is necessary, remove the fuel rail and disconnect the injectors.
• Install new injectors with new O-rings, ensuring they are properly seated.
• Reassemble the fuel rail and reconnect fuel lines.

5. Address Vacuum Leaks

• Tools Required: Vacuum gauge or smoke machine (for testing).
• Use a vacuum gauge to check for proper vacuum levels; if levels are low, inspect hoses and gaskets for leaks.
• Replace any damaged vacuum hoses or gaskets to ensure a proper seal.