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

Solution

1. Preparation

• Gather tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool completely before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Sub-steps:
  1. Locate the upstream oxygen sensor (before the catalytic converter) and the downstream oxygen sensor (after the catalytic converter).
  2. Unplug the electrical connectors from each sensor.
  3. Use the O2 sensor socket to remove the sensors from the exhaust manifold and exhaust pipe.
  4. Install the new sensors and torque them to the manufacturer's specifications (typically around 30 ft-lbs).
  5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Tools Required: Socket set, jack and jack stands, exhaust pipe cutter or reciprocating saw.
• Sub-steps:
  1. Lift the vehicle and secure it with jack stands.
  2. Use the exhaust cutter or saw to remove the catalytic converter from the exhaust system (cutting may be necessary if bolts are rusted).
  3. Install the new catalytic converter, ensuring proper alignment with the exhaust system.
  4. Secure it with bolts/nuts and torque to specifications (usually around 30 ft-lbs).
  5. Reconnect any exhaust hangers or clamps that were removed.

4. Clear the Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle’s computer.