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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool down before starting work.

2. Replace Spark Plugs

• Tools Required: Socket set, spark plug socket, torque wrench.
• Remove the ignition coils by unscrewing the retaining bolts and disconnecting electrical connectors.
• Using the spark plug socket, remove the old spark plugs.
• Inspect the spark plug wells for debris or oil. Clean if necessary.
• Install new spark plugs, ensuring the gap is set to the manufacturer's specifications (typically around 0.044 inches).
• Tighten the spark plugs to the recommended torque (usually around 13 lb-ft).

3. Inspect and Replace Ignition Coils

• Tools Required: Socket set, torque wrench.
• After removing the ignition coils, inspect them for cracks or wear.
• If any ignition coil is damaged, replace it with a new one.
• Reinstall the ignition coils, tightening them to the manufacturer’s specified torque (generally around 10-12 lb-ft).

4. Test Fuel Injectors

• Tools Required: Fuel pressure gauge.
• Connect the fuel pressure gauge to the fuel rail.
• Start the engine and check for proper fuel pressure according to manufacturer specifications (typically around 50-60 psi).
• If the pressure is low, inspect the fuel pump and filter for issues. Replace as necessary.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner.
• Use a smoke machine to detect any vacuum leaks in the intake manifold and associated hoses.
• Alternatively, spray carburetor cleaner around potential leak areas; an increase in RPMs indicates a leak.
• Replace any damaged hoses or gaskets.