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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to prevent electrical shorts.
• Ensure the vehicle is on a level surface and properly supported with jack stands.

2. Inspect and Replace Oxygen Sensors (if needed)

• Tools Required: O2 sensor socket, torque wrench
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually near the exhaust manifold and after the catalytic converter).
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust.
  4. Install the new sensors, tightening to the manufacturer's specified torque (typically around 30-40 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if needed)

• Tools Required: Socket set, torque wrench, exhaust gasket
• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Remove the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
  3. Carefully detach the catalytic converter and inspect for any cracks or blockage.
  4. Install the new catalytic converter, applying a new exhaust gasket.
  5. Torque the bolts to the manufacturer’s specifications (usually around 30-50 lb-ft).

4. Clear Codes and Test Drive

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