how to fix P0420 code in Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Tools Required: OBD-II scanner, jack and jack stands, socket set, multimeter, exhaust pipe cutter.
• Disconnect the battery to prevent electrical shorts.
• Allow the engine to cool completely before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Unplug the electrical connectors on both sensors.
  3. Use a socket wrench to remove the sensors from the exhaust system.
  4. Install new sensors, tightening them to the manufacturer’s specified torque (usually around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter

• Sub-steps:
  1. Use a jack to lift the vehicle securely and remove the undercarriage protective cover if applicable.
  2. Cut the exhaust pipe before and after the catalytic converter using an exhaust pipe cutter.
  3. Remove the catalytic converter from the exhaust system.
  4. Install the new catalytic converter, ensuring proper alignment with the exhaust pipe.
  5. Use exhaust clamps to secure the connections and tighten them to the specified torque (typically 20-25 lb-ft).
  6. Reinstall any protective covers and lower the vehicle.

4. Reset the ECU

• After repairs, reconnect the battery.
• Use the OBD-II scanner to clear the P0420 code from the ECU.