how to fix P0420 code on Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, multimeter, socket set, torque wrench, exhaust pipe wrenches.
• Gather safety equipment including gloves and goggles.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Use the appropriate socket to remove the sensors from the exhaust system.
  4. Install new oxygen sensors by reversing the removal steps, ensuring they are tightened to manufacturer specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors to the sensors.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Inspect the catalytic converter visually for any signs of damage, such as dents or rust.
  2. If replacement is needed, remove the exhaust brackets and bolts securing the catalytic converter to the exhaust system.
  3. Carefully detach the catalytic converter from the exhaust pipe.
  4. Install the new catalytic converter, ensuring all gaskets are replaced and bolts are torqued to the manufacturer's specifications (check service manual for exact values).
  5. Reinstall any exhaust brackets and ensure all connections are secure.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the battery.
  2. Use the OBD-II scanner to clear the P0420 code and any other related codes.
  3. Start the vehicle and allow it to reach operating temperature.
  4. Take the vehicle for a test drive, monitoring for any reoccurrence of the check engine light.