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

Solution

1. Preparation

• Gather tools and parts needed for repair.
• Disconnect the vehicle's negative battery terminal to prevent electrical shorts.
• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, jack and jack stands.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors in the exhaust system.
  2. Disconnect the electrical connectors from both sensors.
  3. Use a socket wrench to remove the sensors from their positions.
  4. Install the new oxygen sensors, tightening them to the manufacturer's specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Remove the exhaust hangers using a socket wrench.
  3. Disconnect any bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
  4. Remove the old catalytic converter.
  5. Install the new catalytic converter, ensuring it is properly aligned.
  6. Reattach bolts and exhaust hangers, tightening to the manufacturer's torque specifications.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the system.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the code does not reappear.