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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety before starting work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust manifold and exhaust pipe.
  4. Install new oxygen sensors by threading them into place and tightening them to the manufacturer's specified torque (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, wrench set, torque wrench, exhaust pipe cutter (if necessary)
• Sub-steps:
  1. Inspect the catalytic converter for physical damage or blockage. If damaged, proceed to replace it.
  2. Remove the bolts securing the catalytic converter to the exhaust system using a socket wrench. If necessary, cut the exhaust pipe with an exhaust pipe cutter.
  3. Install the new catalytic converter, ensuring proper alignment with the exhaust pipe.
  4. Secure the catalytic converter with bolts, tightening them to the manufacturer's specified torque (usually around 30-35 ft-lbs).
  5. Reconnect any exhaust hangers that were disconnected during the removal.

4. Reconnect Battery and Clear Codes

• Sub-steps:
  1. Reconnect the vehicle battery terminal.
  2. Use the OBD-II scanner to clear the check engine light and reset the system.