how to fix P0420 code on my Toyota Highlander Third Generation (2014-2019)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the vehicle is on a level surface and secure it with wheel chocks.

2. Replace Oxygen Sensors (if faulty)

1. Locate the upstream and downstream oxygen sensors on the exhaust system.
2. Disconnect the electrical connectors from both sensors.
3. Using an oxygen sensor socket, remove the faulty sensors.
4. Install new oxygen sensors by threading them into place and tightening them to the manufacturer’s specified torque (typically around 30-40 ft-lbs).
5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Check the catalytic converter for any physical damage or signs of overheating.
2. If replacement is needed, unbolt the exhaust manifold and the exhaust pipe connections to remove the old catalytic converter.
3. Install the new catalytic converter, ensuring all gaskets and seals are in place.
4. Torque the bolts to the specified settings (typically around 25-30 ft-lbs for the exhaust connections).
5. Reconnect any sensors or components that were removed.

4. Clear Codes and Test

1. Reconnect the negative battery terminal.
2. Use the OBD-II scanner to clear the P0420 code from the system.
3. Start the engine and allow it to reach operating temperature.