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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to avoid electrical shorts.
• Ensure the vehicle is on a level surface and secure it with wheel chocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Sub-steps:
  1. Locate the oxygen sensors (bank 1 sensor 1 is before the catalytic converter, and bank 1 sensor 2 is after).
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Using the O2 sensor socket, unscrew the sensors from the exhaust manifold and exhaust pipe.
  4. Install new oxygen sensors, ensuring they are torqued to the manufacturer's specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Wrench set, torque wrench, gasket scraper
• Sub-steps:
  1. Locate the catalytic converter along the exhaust system.
  2. Disconnect the exhaust pipes from the catalytic converter flanges using the appropriate wrench.
  3. Remove any mounting brackets or hangers securing the catalytic converter.
  4. Carefully remove the catalytic converter, ensuring no exhaust leaks remain from the old gasket.
  5. Clean the mounting surface with a gasket scraper to ensure a proper seal for the new converter.
  6. Install the new catalytic converter, securing it to the exhaust system with new gaskets and bolts.
  7. Torque the exhaust bolts to the manufacturer's specifications (usually around 33 ft-lbs).

4. Reconnect Battery and Clear Codes

• Reconnect the vehicle's battery terminals.
• Use an OBD-II scanner to clear the P0420 code from the system.
• Start the engine and allow it to reach operating temperature.