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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, fuel pressure gauge, multimeter.
• Disconnect the negative battery cable to prevent electrical shocks.
• Ensure the engine is cool before starting work.

2. Inspect and Replace Ignition Components

1. Remove Engine Cover:
   • Use a socket set to remove bolts securing the engine cover. Set the cover aside.
2. Check Spark Plugs:
   • Remove spark plug wires or ignition coil connectors.
   • Using a socket, remove spark plugs and inspect for wear (carbon build-up, excessive gap).
   • Replace spark plugs if worn. Recommended gap: 0.044 inches (1.1 mm) for most models.
3. Inspect Ignition Coils:
   • Visually inspect ignition coils for cracks or damage.
   • Test with a multimeter (typically around 0.5-0.7 ohms for primary resistance).
   • Replace any faulty ignition coils.

3. Fuel System Check

1. Connect Fuel Pressure Gauge:
   • Locate the fuel rail and connect the fuel pressure gauge to the test port.
   • Turn the ignition to the ON position (do not start the engine) and check for fuel pressure. It should typically be around 35-50 psi.
2. Replace Fuel Filter (if applicable):
   • If pressure is low, replace the fuel filter according to the manufacturer's guidelines.

4. Inspect Vacuum Hoses

1. Visual Inspection:
   • Check all vacuum hoses for cracks, holes, or disconnections.
   • Replace any damaged hoses with OEM parts.
2. Smoke Test (if necessary):
   • Perform a smoke test to find hidden leaks if visible inspection does not reveal any issues.