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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool down before working on it.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Sub-steps:
  1. Locate the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
  2. Using an O2 sensor socket, carefully unscrew the sensors from the exhaust system.
  3. Inspect the sensors for damage or contamination.
  4. If defective, install new O2 sensors, tightening them to the manufacturer’s specified torque (typically 30-40 ft-lbs).

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter
• Sub-steps:
  1. Lift the vehicle safely using a jack and secure it with jack stands.
  2. Remove any heat shields or brackets that may obstruct access to the catalytic converter.
  3. Use an exhaust pipe cutter or saw to carefully cut the exhaust pipes connected to the catalytic converter.
  4. Remove the old catalytic converter from the vehicle.
  5. Install the new catalytic converter, ensuring proper alignment with exhaust pipes.
  6. Use clamps or welds as necessary to secure the new converter in place.

4. 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.