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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety.
• Allow the exhaust system to cool.

2. Inspect and Replace Oxygen Sensors

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

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter, gasket scraper, new exhaust gaskets
• Sub-steps:
  1. Locate the catalytic converter and visually inspect it for damage or blockage.
  2. If damage is found, use the socket set to unbolt the catalytic converter from the exhaust system.
  3. Cut the exhaust pipes if necessary, ensuring a clean cut for proper fitting of the new converter.
  4. Clean the mating surfaces of the exhaust system to remove old gaskets and debris.
  5. Install the new catalytic converter, using new gaskets and tightening bolts to the specified torque (usually around 30 ft-lbs).
  6. Reconnect any exhaust components removed during the process.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the vehicle battery.
  2. Use an OBD-II scanner to clear the P0420 code from the system.
  3. Start the engine and let it idle for a few minutes.
  4. Take the vehicle for a test drive to allow the system to re-evaluate the catalytic converter's efficiency.