how to fix P0420 code in Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the battery before starting any repairs.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream and downstream oxygen sensors on the exhaust system.
2. Use an O2 sensor socket to remove the sensors from the exhaust pipe.
3. Inspect the sensor connectors for corrosion or damage.
4. Install new oxygen sensors by reversing the removal process, ensuring proper torque (typically around 30-40 ft-lbs).
5. Reconnect the battery.

3. Inspect and Replace the Catalytic Converter (if necessary)

1. Raise the vehicle using a jack and secure with jack stands.
2. Remove the exhaust pipe bolts connecting to the catalytic converter using a socket set.
3. Detach any hangers or clamps holding the catalytic converter in place.
4. Inspect the new catalytic converter to ensure it matches the old one.
5. Install the new catalytic converter, ensuring all gaskets are replaced and all bolts are torqued to manufacturer specifications (refer to service manual for torque values).
6. Reinstall any hangers or clamps.

4. Clear Codes and Test Drive

1. Use the OBD-II scanner to clear the P0420 code.
2. Start the engine and allow it to reach operating temperature.
3. Conduct a test drive to ensure no codes reappear and the vehicle operates normally.