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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Replace Ignition Components

• Tools Required: Socket set, torque wrench, spark plug socket, ignition coil puller.
• Remove the engine cover (if applicable) using the socket set.
• Carefully disconnect the ignition coils by pulling up on the connectors.
• Remove the ignition coils from the spark plugs by unscrewing them with the socket set.
• Inspect spark plugs for wear; replace if they are worn or fouled.
• Install new spark plugs and torque them to the manufacturer’s specifications (typically 13-15 lb-ft).
• Reinstall the ignition coils, ensuring they are seated properly, and reconnect the electrical connectors.

3. Fuel System Check

• Tools Required: Fuel pressure gauge.
• Locate the fuel rail and connect the fuel pressure gauge.
• Turn the ignition to the "ON" position (without starting the engine) to check the fuel pressure; it should be within the manufacturer’s specifications (typically around 30-50 psi).
• If the pressure is low, check the fuel pump and filter for blockages or failures, replacing as necessary.

4. Vacuum Leak Inspection

• Tools Required: Smoke machine or carburetor cleaner.
• Start the engine and use a smoke machine to detect any vacuum leaks around the intake manifold and hoses.
• If using carburetor cleaner, spray along the intake manifold and hoses while the engine idles; a change in RPM indicates a vacuum leak.
• Repair or replace any damaged hoses or gaskets found.

5. Compression Test

• Tools Required: Compression tester.
• Remove spark plugs and insert the compression tester into the spark plug hole.
• Crank the engine and record the compression readings for each cylinder; they should be within the manufacturer’s specifications.
• If any cylinder shows significantly lower compression, further investigation into potential internal engine issues may be necessary.