how to fix P0300 code on my Toyota RAV4 XA40 (2013-2018)

Solution

1. Preparation

• Gather tools and materials: OBD-II scanner, socket set, torque wrench, multimeter, fuel pressure gauge, compression tester, new spark plugs, ignition coils (if necessary).
• Ensure the vehicle is parked on a flat surface, and the engine is cool.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Disconnect the negative battery terminal.
  2. Remove the engine cover (if applicable) by unscrewing any fasteners.
  3. Carefully disconnect the ignition coil connectors and remove the ignition coils.
  4. Use a spark plug socket to remove the old spark plugs.
  5. Inspect the old spark plugs for wear and replace them with new ones, ensuring they are gapped correctly to manufacturer specifications.
  6. Reinstall the ignition coils and reconnect the connectors.

3. Test and Replace Ignition Coils

• Sub-steps:
  1. Use a multimeter to test the resistance of each ignition coil (consult the vehicle service manual for specifications).
  2. If any coil is out of specification, replace it with a new one.
  3. Reinstall the ignition coils and reconnect the connectors.

4. Check Fuel Pressure

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail’s test port.
  2. Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading against manufacturer specifications.
  3. If the pressure is low, inspect the fuel pump and fuel filter for replacement.

5. Inspect for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses for cracks, loose connections, or damage.
  2. Use a smoke machine or carburetor cleaner around the intake manifold and vacuum lines while the engine is running to detect any leaks.
  3. Repair or replace any damaged hoses or components.

6. Perform Compression Test

• Sub-steps:
  1. Remove all spark plugs and disconnect the fuel pump fuse to prevent fuel delivery.
  2. Insert the compression tester into the spark plug hole of each cylinder.
  3. Crank the engine and note the compression readings for each cylinder; they should be within manufacturer specifications.
  4. If any cylinder has low compression, further investigation is needed (e.g., checking valves or head gasket).