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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle battery to ensure safety while working on the electrical components.
• Raise the vehicle with a jack and secure it with jack stands.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench set, anti-seize compound.
• Sub-steps:
  1. Locate the upstream (before catalytic converter) and downstream (after catalytic converter) oxygen sensors in the exhaust system.
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Use the O2 sensor socket to remove the sensors from the exhaust pipe.
  4. Apply anti-seize compound to the threads of the new sensors.
  5. Install the new sensors and tighten them to the manufacturer's specifications (typically around 30-40 ft-lbs).
  6. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust pipe cutter, gasket scraper, new gasket, torque wrench.
• Sub-steps:
  1. Inspect the catalytic converter for any signs of damage or blockage.
  2. If replacement is needed, cut the exhaust pipe leading to the catalytic converter using the exhaust pipe cutter.
  3. Remove any remaining gasket material from the exhaust flanges.
  4. Install the new catalytic converter, ensuring it is aligned properly.
  5. Tighten the bolts to the specified torque (usually around 30-35 ft-lbs).
  6. Replace any heat shields if removed.

4. Reset the ECU

• Reconnect the vehicle battery.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.
• Start the engine and allow it to reach operating temperature.