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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Apply penetrating oil to the sensor threads if they are corroded.
  3. Disconnect the electrical connectors from both O2 sensors.
  4. Using the O2 sensor socket, remove the sensors from the exhaust system.
  5. Install new sensors, tightening them to the manufacturer's specified torque (typically around 30 ft-lbs).
  6. Reconnect the electrical connectors.

3. Check or Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if necessary), gasket scraper.
• Sub-steps:
  1. If the catalytic converter is damaged or not functioning correctly, it must be replaced.
  2. Loosen the bolts securing the catalytic converter to the exhaust manifold and the exhaust pipe.
  3. Carefully remove the catalytic converter, ensuring no additional damage to the exhaust system.
  4. Clean the mating surfaces on the exhaust manifold and pipe using a gasket scraper.
  5. Install the new catalytic converter, making sure to use new gaskets if required.
  6. Torque the bolts to the manufacturer's specifications (typically around 30 ft-lbs).

4. Reset the Engine Control Module (ECM)

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the ECM.
  3. Start the engine and allow it to reach normal operating temperature.