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

Solution

1. Preparation

• Gather necessary tools and parts before starting.
• Disconnect the negative battery terminal to prevent electrical issues.
• Allow the engine to cool down before working on the exhaust system.

2. Inspect and Repair Exhaust Leaks

• Sub-steps:
  1. Use a flashlight to inspect the exhaust system for visible leaks.
  2. If leaks are found, use high-temperature exhaust sealant or replace damaged sections of the exhaust pipe.
  3. Ensure all connections are tight to prevent exhaust leaks.

3. Replace Oxygen Sensors (if faulty)

• Tools Required: O2 sensor socket, ratchet, and extension.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from the sensors.
  3. Using the O2 sensor socket, remove the faulty sensors.
  4. Install the new sensors and connect the electrical connectors.
  5. Ensure they are tightened to manufacturer specifications (usually about 30 ft-lbs).

4. Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Sub-steps:
  1. Remove the exhaust hangers and disconnect the catalytic converter from the exhaust system.
  2. Use the socket set to remove the bolts securing the catalytic converter.
  3. Install the new catalytic converter, ensuring proper alignment.
  4. Torque the bolts to the manufacturer's specifications (typically around 30-40 ft-lbs).
  5. Reinstall the exhaust hangers.

5. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other related codes.