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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.
• Allow the engine to cool completely before starting work.

2. Inspect and Replace Spark Plugs

• Tools Required: Spark plug socket, torque wrench, ratchet, gap gauge.
• Remove the ignition coils by unscrewing any retaining bolts and disconnecting the electrical connectors.
• Carefully remove the spark plugs using the spark plug socket.
• Inspect the spark plugs for signs of wear, damage, or incorrect gap.
• Replace any faulty spark plugs with new ones, ensuring they are gapped correctly according to manufacturer specifications (usually around 0.043 inches).
• Reinstall the ignition coils and reconnect electrical connectors.

3. Check and Replace Ignition Coils

• Tools Required: Socket set, torque wrench.
• If misfire persists, remove the ignition coils as previously described.
• Test each ignition coil with a multimeter; check for primary and secondary resistance.
• Replace any faulty ignition coils with new ones, ensuring they are torqued to the manufacturer's specifications.

4. Inspect Fuel Injectors

• Tools Required: Fuel pressure gauge, injector cleaning kit (if needed).
• Check fuel pressure at the rail using a fuel pressure gauge; it should match the specifications in the service manual.
• If fuel pressure is low, inspect the fuel pump and filter for issues.
• Clean or replace clogged fuel injectors as necessary.

5. Inspect for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner.
• Use a smoke machine to identify any vacuum leaks in the intake system.
• Alternatively, spray carburetor cleaner around the intake manifold while the engine is running to listen for changes in engine RPM.
• Repair any leaks found in hoses or gaskets.

6. Replace Air Filter

• Tools Required: None (usually hand tools).
• Access the air filter housing by unclipping or unscrewing it.
• Remove the old air filter and replace it with a new one, ensuring a snug fit.