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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Ignition Components

• Tools Required: Socket set, torque wrench, ratchet, pliers
• Remove the engine cover (if applicable) by loosening the retaining bolts.
• Disconnect the electrical connectors from the ignition coils.
• Remove the ignition coils by unbolting them and lifting them out.
• Inspect the spark plugs; if they are worn or fouled, replace them with OEM specifications.
• Install new spark plugs by hand-tightening, then torque to manufacturer specifications (usually around 13 ft-lbs).
• Reinstall the ignition coils, ensuring they are seated properly, then reconnect the electrical connectors.

3. Fuel System Inspection

• Tools Required: Fuel pressure gauge
• Locate the fuel rail and connect the fuel pressure gauge.
• Turn the ignition on (do not start the engine) to check the fuel pressure. It should match the manufacturer's specifications (usually around 50-60 PSI).
• If the pressure is low, check the fuel filter and replace if clogged. If the filter is fine, the fuel pump may need replacement.

4. Air Intake and Vacuum System Check

• Tools Required: Screwdriver set, vacuum gauge
• Inspect the air intake duct for cracks or loose fittings and replace any damaged sections.
• Check the vacuum lines for any signs of wear or leakage; replace any damaged lines.
• Use a vacuum gauge to check for proper vacuum levels at idle; low readings may indicate an intake leak.

5. Compression Test

• Tools Required: Compression tester
• Remove the spark plugs and insert the compression tester into each cylinder.
• Crank the engine for several seconds and record the compression readings.
• Compare the readings to the manufacturer's specifications; significant deviations may indicate internal engine issues.