how to address P0303 misfire code in Toyota Highlander Third Generation (2014-2019)?

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool down before starting work.

2. Replace Spark Plug

1. Remove the engine cover (if equipped) by unscrewing the retaining bolts.
2. Using a spark plug socket and ratchet, remove the spark plug from cylinder 3.
3. Inspect the old spark plug for damage or excessive wear and gap it to the manufacturer’s specifications (typically 0.044 inches for this model).
4. Insert a new spark plug and tighten to the manufacturer’s torque specification (approximately 13 lb-ft).
5. Reconnect the ignition coil.

3. Replace Ignition Coil

1. Disconnect the electrical connector from the ignition coil on cylinder 3.
2. Remove the mounting bolts securing the ignition coil.
3. Pull the ignition coil straight out to avoid damaging the spark plug tube.
4. Install the new ignition coil and secure it with the mounting bolts (torque to manufacturer specifications).
5. Reconnect the electrical connector to the ignition coil.

4. Inspect/Replace Fuel Injector

1. Disconnect the fuel injector connector for cylinder 3.
2. Remove the fuel rail if necessary (ensure the fuel system is depressurized).
3. Remove the old fuel injector from the rail.
4. Lubricate the O-ring of the new injector with clean engine oil and install it into the fuel rail.
5. Reinstall the fuel rail and reconnect the fuel injector connector.

5. Verify Installation

• Double-check all connections and ensure all components are securely installed.
• Reconnect the negative battery terminal.