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

Solution

1. Preparation

• Gather necessary tools and parts.
• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the negative terminal of the battery.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, multimeter.
• Sub-steps:
  1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  2. Use the O2 sensor socket to remove the upstream sensor.
  3. Inspect the sensor for damage; test using a multimeter to check resistance.
  4. If faulty, install a new oxygen sensor, tightening to the manufacturer's specifications (usually around 30-40 ft-lbs).
  5. Repeat steps 2-4 for the downstream oxygen sensor.

3. Inspect the Catalytic Converter

• Tools Required: Jack and jack stands, exhaust pipe cutter (if needed).
• Sub-steps:
  1. Raise the vehicle using a jack and secure with jack stands.
  2. Visually inspect the catalytic converter for any physical damage or signs of clogging.
  3. If the converter is clogged, use an exhaust pipe cutter to carefully remove it from the exhaust system.
  4. Replace with a new catalytic converter, ensuring proper alignment and sealing.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Reconnect the battery's negative terminal.
  2. Use the OBD-II scanner to clear the P0420 code from the ECU.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.