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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the vehicle's battery to prevent electrical issues.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the pre-catalytic oxygen sensor by:
  • Locating the sensor upstream from the catalytic converter.
  • Using the O2 sensor socket to unscrew and remove the sensor.
  • Installing the new sensor and tightening it to the manufacturer's specified torque (usually around 30 lb-ft).
• Repeat the process for the post-catalytic oxygen sensor if it shows signs of failure.

3. Inspect and Clean the Catalytic Converter

• Tools Required: Wrench set, cleaning solution (if applicable)
• Remove the catalytic converter from the exhaust system:
  • Locate the bolts securing the catalytic converter to the exhaust pipe and unbolt them.
  • Carefully remove the catalytic converter.
• Clean the catalytic converter using a specialized cleaning solution, ensuring to follow the product instructions. If severely damaged, replacement may be necessary.

4. Reinstall Components

• Reinstall the catalytic converter by reversing the removal steps:
  • Secure the catalytic converter with bolts and tighten to manufacturer’s specifications.
  • Reinstall any heat shields if removed.
• Reconnect the pre-catalytic and post-catalytic oxygen sensors.

5. Reconnect the Battery

• Reconnect the vehicle's battery and ensure all connections are secure.

6. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code and any other codes present.