how do I resolve the P0420 code on my Toyota Highlander Third Generation (2014-2019)?

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety while working on the electrical components.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Use the O2 sensor socket to remove both sensors.
  3. Inspect the sensor tips for damage.
  4. If faulty, replace with new sensors, ensuring they are properly torqued (typically 30-40 ft-lbs).
  5. Reconnect electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, cutting tool (if needed), exhaust pipe clamps.
• Sub-steps:
  1. If the catalytic converter is found to be clogged or damaged, remove it by loosening the exhaust clamps and disconnecting it from the exhaust piping.
  2. Install the new catalytic converter, ensuring that it is aligned properly with the exhaust system.
  3. Secure the converter using clamps and ensure all connections are tight.

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 memory.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure that the check engine light does not reappear.