how to fix P0300 random misfire code on my Toyota RAV4 Fifth Generation (2019-present)

Solution

1. Preparation

• Gather tools and materials needed for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before starting any work.

2. Inspect and Replace Ignition Components

• Sub-steps:
  1. Remove engine cover (if applicable) using a socket set.
  2. Disconnect the ignition coil connectors and remove the ignition coils from each cylinder.
  3. Inspect spark plugs for wear; replace if worn or fouled.
  4. Install new spark plugs (torque to manufacturer's specifications, typically around 13-15 lb-ft).
  5. Reinstall ignition coils and reconnect connectors, ensuring a secure fit.

3. Check and Clean Fuel System

• Sub-steps:
  1. Remove the fuel pump relay and start the engine to relieve fuel pressure.
  2. Inspect fuel injectors for clogs; clean or replace as necessary.
  3. Use a fuel pressure gauge to check the fuel pressure against specifications (typically 50-60 psi).
  4. If the pressure is low, inspect the fuel filter and pump for blockages or failures.

4. Inspect for Vacuum Leaks

• Sub-steps:
  1. With the engine running, listen for hissing sounds indicating a vacuum leak.
  2. Use a smoke machine or carburetor cleaner to locate leaks around the intake manifold and hoses.
  3. Replace any damaged hoses or gaskets.

5. Test Engine Compression

• Sub-steps:
  1. Remove spark plugs and connect a compression gauge to each cylinder.
  2. Crank the engine and record compression readings.
  3. Compare readings to manufacturer specifications (typically around 180-200 psi).
  4. If readings are below specifications, investigate potential internal engine issues.

6. Clean MAF Sensor and Throttle Body

• Sub-steps:
  1. Disconnect the MAF sensor connector and remove it from the air intake.
  2. Use MAF cleaner to gently clean the sensor element, avoiding contact with any components.
  3. Remove the throttle body and use throttle body cleaner to remove carbon buildup.
  4. Reinstall both components after cleaning.