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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent any electrical shorts.
• Make sure the vehicle is on a level surface, and raise it using a jack and jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust pipe.
  4. Install the new oxygen sensors and torque them to the manufacturer's specifications (usually around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect or Replace Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter (if necessary), gasket scraper
• Sub-steps:
  1. Inspect the catalytic converter for any physical damage or blockage.
  2. If necessary, use an exhaust pipe cutter to remove the old catalytic converter from the exhaust system.
  3. Clean the mounting surfaces to ensure a proper seal.
  4. Install the new catalytic converter and torque the bolts to the manufacturer's specifications.
  5. Reconnect any exhaust hangers and ensure everything is secure.

4. Clear Codes and Test

• Tools Required: OBD-II scanner
• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.
  3. Start the vehicle and let it reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.