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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative terminal of the battery to ensure safety.
• Allow the vehicle to cool down if it has been running.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, and torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (typically found before and after the catalytic converter).
  2. Disconnect the electrical connectors from each oxygen sensor.
  3. Use the O2 sensor socket to remove the sensors from the exhaust system.
  4. Install the new oxygen sensors by threading them into place and tightening them to the manufacturer’s specifications (usually around 30-40 ft-lbs).
  5. Reconnect the electrical connectors to the sensors.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter (if necessary), and torque wrench.
• Sub-steps:
  1. Identify the catalytic converter’s location within the exhaust system.
  2. Use the socket set to loosen and remove the bolts securing the catalytic converter to the exhaust pipes.
  3. If necessary, cut the exhaust pipe using an exhaust pipe cutter to remove the old catalytic converter.
  4. Install the new catalytic converter by positioning it between the exhaust pipes and securing it with bolts to the manufacturer’s torque specifications (typically around 30-35 ft-lbs).
  5. Ensure all connections are secure and check for any exhaust leaks.

4. Clear Error Codes

• Use the OBD-II scanner to clear the P0420 code from the vehicle’s memory after completing the repairs.
• Reconnect the negative battery terminal.