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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent electrical shorts.
• Ensure the vehicle is on a level surface and properly supported with jack stands if needed.

2. Inspect and Replace Oxygen Sensors (if necessary)

• 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. Using the O2 sensor socket, remove the sensors by turning counterclockwise.
  4. Install new sensors by reversing the removal process. Tighten to manufacturer torque specifications (usually around 30 lb-ft).
  5. Reconnect electrical connectors ensuring a tight fit.

3. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe clamps, gasket scraper.
• Sub-steps:
  1. Remove any bolts or clamps securing the catalytic converter to the exhaust system using a socket set.
  2. Carefully lower the catalytic converter from the exhaust system.
  3. Clean the mating surfaces on the exhaust pipes to ensure a proper seal.
  4. Install the new catalytic converter, aligning it properly and securing it with bolts or clamps to the manufacturer's torque specifications.
  5. Reinstall any heat shields that may have been removed during the process.

4. Reset the Engine Control Module (ECM)

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