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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shock.
• Allow the exhaust system to cool before beginning work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench, multimeter
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Use the O2 sensor socket to carefully remove the oxygen sensors.
  3. Inspect the sensors for damage or contamination.
  4. If faulty, replace with new sensors, ensuring to torque them to manufacturer specifications (typically around 30 lb-ft).

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

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter or saw, gasket scraper
• Sub-steps:
  1. Raise the vehicle and securely support it with jack stands.
  2. Remove any heat shields or components obstructing access to the catalytic converter.
  3. Use the exhaust pipe cutter or saw to remove the old catalytic converter from the exhaust system.
  4. Clean the mating surfaces on the exhaust pipes with a gasket scraper.
  5. Install the new catalytic converter, ensuring proper alignment and sealing.
  6. Reinstall any heat shields or components that were removed.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and allow it to reach operating temperature.
  4. Perform a test drive to verify the repair.