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

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, fuel pressure gauge, compression tester.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before proceeding with any repairs.

2. Inspect Ignition System

• Sub-steps:
  1. Remove the engine cover if present, using a socket set.
  2. Inspect spark plugs for wear or damage; replace if necessary (use OEM specifications).
  3. Test each ignition coil using a multimeter for primary and secondary resistance.
  4. Replace any faulty ignition coils with new, OEM parts.

3. Check Fuel System

• Sub-steps:
  1. Connect a fuel pressure gauge to the fuel rail.
  2. Turn the ignition to the "ON" position (do not start) and check pressure; it should meet OEM specifications.
  3. If pressure is low, inspect the fuel pump, filter, and lines for blockages or leaks.
  4. Replace the fuel filter if clogged and the fuel pump if it fails to meet pressure requirements.

4. Inspect for Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum hoses connected to the intake manifold for cracks or disconnections.
  2. Use a smoke machine or carburetor cleaner to check for leaks while the engine is running.
  3. Replace any damaged hoses and reseal connections as necessary.

5. Compression Test

• Sub-steps:
  1. Remove the spark plugs from each cylinder.
  2. Insert a compression tester into the spark plug hole and crank the engine.
  3. Record the compression readings and compare them to OEM specifications.
  4. If any cylinder readings are low, investigate further for potential internal engine issues.