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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Park the vehicle on a level surface and engage the parking brake.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors (usually near the exhaust manifold and behind the catalytic converter).
  2. Disconnect the electrical connectors from both oxygen sensors.
  3. Use the O2 sensor socket to remove the old sensors and inspect the threads for damage.
  4. Install the new sensors and torque to the manufacturer’s specification (usually around 30 ft-lbs).
  5. Reconnect the electrical connectors securely.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust hanger removal tool.
• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Disconnect any exhaust pipes connected to the catalytic converter using appropriate sockets.
  3. Use the exhaust hanger removal tool to detach the catalytic converter from its hangers.
  4. Install the new catalytic converter by reversing the removal steps.
  5. Ensure all connections are tight and torque to the manufacturer’s specifications.

4. Clear Codes and Test Drive

• 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 vehicle’s computer.
  3. Start the engine and let it idle for a few minutes.
  4. Take the vehicle for a test drive to ensure the check engine light does not reappear.