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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety.
• Allow the engine to cool before starting work on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Use the O2 sensor socket to remove the upstream sensor first, then the downstream sensor.
  4. Install the new oxygen sensors and torque them to the manufacturer’s specifications (usually around 30 ft-lbs).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Sub-steps:
  1. Visually inspect the catalytic converter for damage or blockage.
  2. If replacement is needed, disconnect the exhaust pipes from the catalytic converter using the socket set.
  3. Remove the mounting bolts and exhaust hangers.
  4. Install the new catalytic converter, ensuring proper alignment.
  5. Torque all bolts to the manufacturer’s specifications (typically 30-45 ft-lbs).
  6. Reconnect any exhaust hangers and ensure all connections are secure.

4. Clear Codes and Test

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