how to fix P0420 code in my 2019 Toyota Corolla E210?

Solution

1. Preparation

• Gather all necessary tools and materials.
• Disconnect the negative battery terminal to prevent electrical shocks.
• Allow the engine to cool down completely.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, socket wrench, penetrating oil.
• Instructions:
  1. Locate the upstream and downstream oxygen sensors on the exhaust system.
  2. Apply penetrating oil to the sensor threads and let it sit for a few minutes.
  3. Using the O2 sensor socket, carefully unscrew the sensors from their positions.
  4. Install new oxygen sensors in the correct orientation and torque to manufacturer specifications (generally around 30 lb-ft).
  5. Reconnect the electrical connectors for both sensors.

3. Inspect and Replace Catalytic Converter (if needed)

• Tools Required: Wrench set, jack and jack stands, exhaust pipe cutter, new gaskets.
• Instructions:
  1. Raise the vehicle securely using jack stands.
  2. Locate the catalytic converter in the exhaust system.
  3. Inspect for physical damage; if necessary, remove the catalytic converter by unbolting it from the exhaust pipe and manifold.
  4. Install the new catalytic converter, ensuring proper alignment and sealing with new gaskets.
  5. Torque all bolts to the specified values (usually around 25-30 lb-ft).

4. Reconnect Battery

• Reconnect the negative battery terminal securely.

5. Clear Codes and Test Drive

• Use the OBD-II scanner to clear the P0420 code.
• Test drive the vehicle to ensure the system is functioning properly.