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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety while working on the vehicle.

2. Replace Damaged Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors; they are typically located in the exhaust manifold (upstream) and just before the catalytic converter (downstream).
  2. Disconnect the electrical connectors from both sensors.
  3. Use the O2 sensor socket to remove the faulty sensor from its mounting point.
  4. Apply anti-seize compound to the threads of the new sensor (if recommended).
  5. Install the new sensor and tighten it to the manufacturer’s specified torque (usually around 30 lb-ft).
  6. Reconnect the electrical connectors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, exhaust clamps, gaskets, and possibly a saw or cutting tool if the converter is welded.
• Sub-steps:
  1. Remove the exhaust pipes connected to the catalytic converter by loosening the clamps or bolts.
  2. If welded, carefully cut the old catalytic converter out using a saw, ensuring you do not damage the surrounding exhaust components.
  3. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  4. Secure it with new gaskets and clamps, tightening to the manufacturer's specified torque.

4. Reconnect Battery and Conduct Final Checks

• Reconnect the negative battery terminal.
• Start the engine and let it reach operating temperature.