how to fix P0300 random misfire code in my Toyota RAV4 XA50 (2019-2024)

Solution

1. Preparation

• Gather required tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is off.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Spark Plugs

• Sub-steps:
  1. Remove the engine cover if present (using socket set).
  2. Disconnect the ignition coil connectors and remove the coils (using socket set).
  3. Remove the spark plugs using a spark plug socket and ratchet.
  4. Inspect old spark plugs for wear or damage; replace with OEM spark plugs if necessary.
  5. Reinstall spark plugs and torque to manufacturer specifications (typically 13-16 ft-lbs).
  6. Reinstall ignition coils and reconnect connectors.

3. Check and Replace Ignition Coils

• Sub-steps:
  1. If misfire persists after replacing spark plugs, test ignition coils with a multimeter for proper resistance.
  2. Remove faulty ignition coils and replace with OEM parts.
  3. Reconnect the battery and clear codes with the OBD-II scanner.

4. Fuel System Inspection

• Sub-steps:
  1. Check fuel pressure using a fuel pressure gauge; it should be within manufacturer specifications (usually 35-50 psi).
  2. If low, inspect the fuel filter and replace if clogged.
  3. Inspect the fuel injectors for proper operation; clean or replace as necessary.

5. Air Intake and Vacuum System Check

• Sub-steps:
  1. Inspect air intake hoses for cracks or loose connections and replace as needed.
  2. Clean the mass airflow sensor with a specialized cleaner.
  3. Check all vacuum hoses and replace any that are damaged or disconnected.