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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shocks.
• Allow the vehicle to cool down if the engine has been running.

2. Inspect and Replace O2 Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) O2 sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the sensors from their respective locations.
  4. Install the new O2 sensors, tightening them to the manufacturer’s specifications (usually around 30-40 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torch (if bolts are rusted), torque wrench.
• Sub-steps:
  1. Loosen and remove the bolts securing the catalytic converter to the exhaust system.
  2. Carefully remove the catalytic converter from the exhaust system.
  3. Inspect the mounting surfaces for any damage or debris.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Torque the bolts to the manufacturer’s specifications (often around 25-35 lb-ft).
  6. Reconnect any heat shields or supports that were removed.

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 let it reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear and the vehicle operates normally.