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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  • Locate the upstream and downstream oxygen sensors.
  • Use an O2 sensor socket to remove the sensors from the exhaust system.
  • Inspect the wiring and connectors for damage; replace any damaged components.
  • Install new oxygen sensors and torque to the manufacturer’s specifications (typically around 30-40 ft-lbs).
  • Reconnect the battery terminal.

3. Inspect and Replace the Catalytic Converter

• Sub-steps:
  • If the catalytic converter is faulty, locate the component in the exhaust system.
  • Remove any heat shields covering the catalytic converter using a socket wrench.
  • Use a cutting tool if necessary to detach the catalytic converter from the exhaust pipes.
  • Install the new catalytic converter, ensuring that all gaskets are replaced and connections are secure.
  • Torque all bolts to manufacturer specifications (usually around 30-45 ft-lbs).

4. Clear Codes and Test Drive

• Sub-steps:
  • Use an OBD-II scanner to clear the error codes from the vehicle's computer.
  • Start the engine and allow it to reach operating temperature.
  • Take the vehicle for a test drive to ensure the check engine light does not return.