how to fix P0300 misfire code in Toyota RAV4 XA40 (2013-2018)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, fuel pressure gauge, multimeter.
• Park the vehicle on a level surface, turn off the ignition, and disconnect the negative battery terminal.

2. Inspect and Replace Spark Plugs

• Remove the ignition coil covers if applicable.
• Disconnect the ignition coil connectors and remove the coils using a socket.
• Remove the spark plugs with a spark plug socket.
• Inspect the spark plugs for wear (check gap and condition); replace with OEM-spec plugs if worn.
• Reinstall the spark plugs and torque to the manufacturer’s specification (usually around 13-15 ft-lbs).
• Reinstall the ignition coils and reconnect the connectors.

3. Check and Replace Ignition Coils

• If misfire persists after spark plug replacement, test ignition coils with a multimeter (check primary and secondary resistance).
• Replace any faulty ignition coils with OEM parts.
• Reinstall coils, ensuring they are seated properly.

4. Inspect and Clean Fuel Injectors

• Attach a fuel pressure gauge to the fuel rail to check for proper pressure (usually around 40-50 psi).
• If pressure is low, check for a clogged fuel filter or failing fuel pump.
• Remove fuel injectors and inspect for clogs; clean or replace if necessary.
• Reinstall injectors, ensuring proper sealing.

5. Check for Vacuum Leaks

• Visually inspect all vacuum hoses and intake gaskets for cracks or disconnections.
• Use a smoke machine or carburetor cleaner to detect any vacuum leaks.
• Repair or replace any damaged hoses or gaskets found during inspection.

6. Test Engine Compression

• Remove spark plugs and perform a compression test on all cylinders.
• Compare compression values; values should be within manufacturer specifications (usually around 150-200 psi).
• Address any low compression readings with appropriate repairs (e.g., valve adjustments, head gasket replacement).