how to fix P0303 code in Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

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

2. Replace Spark Plug and Ignition Coil (if necessary)

• Remove the engine cover (if applicable) using a socket set.
• Disconnect the electrical connector from the ignition coil on cylinder 3.
• Remove the ignition coil by unbolting it and pulling it out of the spark plug well.
• Use a spark plug socket to remove the spark plug from cylinder 3.
• Inspect the old spark plug for signs of wear or damage; replace if necessary.
• Install the new spark plug and torque it to the manufacturer’s specifications (typically around 13-16 lb-ft).
• Reinstall the ignition coil and reconnect the electrical connector.

3. Test or Replace Fuel Injector

• Disconnect the fuel injector connector for cylinder 3.
• Use a multimeter to test the injector’s resistance; refer to the service manual for specifications.
• If the injector is faulty, replace it by unbolting and removing it from the fuel rail. Install the new injector and reconnect the fuel line.

4. Compression Testing (if misfire persists)

• If the misfire continues, perform a compression test on cylinder 3.
• If compression is below specifications, further diagnosis may be needed (e.g., valve issues, head gasket failure).
• Repair any mechanical issues found during compression testing.