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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Park the vehicle on a flat surface and engage the parking brake.
• Disconnect the negative battery terminal to avoid electrical shocks.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, and torque wrench.
• Remove the upstream oxygen sensor (pre-catalytic converter) by:
  • Using the O2 sensor socket to unscrew it.
  • Installing the new oxygen sensor and torque it to manufacturer specifications (typically around 30 lb-ft).
• Repeat the process for the downstream oxygen sensor (post-catalytic converter) if needed.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Wrench set, jack and jack stands, exhaust pipe cutter (if needed).
• Raise the vehicle using a jack and secure it with jack stands.
• Remove the exhaust pipe connected to the catalytic converter:
  • Loosen the bolts and carefully detach the pipe.
• Inspect the catalytic converter for damage; if it’s clogged or broken, replace it:
  • Unscrew the mounting bolts holding the catalytic converter.
  • Install the new catalytic converter and secure it with bolts.
  • Reconnect the exhaust pipe and ensure all connections are tight.

4. Clear Codes and Test Drive

• Reconnect the battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the system.
• Take the vehicle for a test drive to monitor for any recurring issues.