how to fix P0420 code on Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust manifold and catalytic converter.
  4. Install the new sensors by threading them into place and tightening to the manufacturer's specifications (usually 30-40 ft-lbs).
  5. Reconnect the electrical connectors to the new sensors.

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

• Tools Required: Wrench set, exhaust pipe cutter or saw, gasket scraper
• Sub-steps:
  1. If the catalytic converter is suspected to be faulty, locate the catalytic converter in the exhaust system.
  2. Remove the exhaust pipes connected to the catalytic converter using appropriate tools.
  3. Carefully unbolt the catalytic converter from the exhaust system.
  4. Clean the mating surfaces of the exhaust system using a gasket scraper.
  5. Install the new catalytic converter, ensuring proper alignment and using new gaskets if required.
  6. Reconnect the exhaust pipes securely.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals.
• Use the OBD-II scanner to clear the P0420 code and any related trouble codes.

5. Test Drive

• Start the vehicle and allow it to reach operating temperature.
• Monitor for any warning lights on the dashboard and verify normal engine operation.