how to fix P0303 code in Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

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

2. Inspect and Replace Spark Plug

• Tools Required: Socket set, torque wrench
• Remove the ignition coil from Cylinder 3.
• Remove the spark plug using a spark plug socket.
• Inspect the spark plug for wear (electrode condition, carbon buildup).
• Replace the spark plug if damaged or worn. Ensure it is gapped according to specifications.
• Reinstall the spark plug and ignition coil.

3. Check and Replace Ignition Coil (if necessary)

• Still using the socket set, remove the ignition coil for Cylinder 3.
• Inspect for cracks or wear on the ignition coil.
• If faulty, replace the ignition coil with a new one, ensuring it is seated correctly.
• Reconnect the electrical connector securely.

4. Inspect and Replace Fuel Injector (if necessary)

• Disconnect the fuel line and remove the fuel injector from Cylinder 3.
• Inspect for clogs or leaks in the fuel injector.
• Replace the fuel injector if it is not functioning properly.
• Reinstall the fuel injector, ensuring proper sealing and connection.

5. Reassemble and Test

• Reconnect the negative battery terminal.
• Start the engine and allow it to idle.
• Monitor for any check engine light illumination or abnormal sounds.