how to fix P0300 random misfire code in Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent any electrical shorts during the repair.
• Ensure the engine is cool before starting the repair.

2. Replace Spark Plugs

• Tools Required: Socket set, torque wrench, spark plug socket
• Remove the ignition coil cover if applicable.
• Remove the spark plug wire or ignition coil (if equipped) by pulling it straight out.
• Use the spark plug socket to carefully unscrew the old spark plug from the cylinder head.
• Inspect the old spark plug for signs of wear or damage.
• Install the new spark plug by hand to avoid cross-threading, then torque to the manufacturer’s specifications (usually around 13-16 lb-ft).
• Reattach the ignition coil or spark plug wire.

3. Inspect and Replace Ignition Coils

• Tools Required: Socket set, multimeter (for testing)
• Disconnect the electrical connector from the ignition coil.
• Remove the coil using the socket set.
• Test the ignition coil with a multimeter; check resistance according to manufacturer specifications.
• Replace any faulty coils with new ones.
• Reinstall the ignition coils and reconnect the electrical connectors.

4. Fuel Injector Inspection and Cleaning

• Tools Required: Fuel pressure gauge, fuel injector cleaning kit
• Attach the fuel pressure gauge to the fuel rail to check for proper fuel pressure.
• If pressure is low, inspect the fuel filter and replace if clogged.
• For cleaning, use a fuel injector cleaning kit according to the manufacturer's instructions, or replace the fuel injectors if they are faulty.

5. Check for Vacuum Leaks

• Tools Required: Smoke machine or carburetor cleaner
• Use a smoke machine to detect vacuum leaks; alternatively, spray carburetor cleaner around vacuum hoses and intake manifold while the engine is running.
• Listen for any changes in engine sound which would indicate a leak.
• Replace any damaged hoses and reseal gaskets as necessary.