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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to ensure safety.
• Raise the vehicle using a jack and secure it on jack stands.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Sub-steps:
  1. Locate the upstream (before the catalytic converter) and downstream (after the catalytic converter) oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an O2 sensor socket to remove the upstream sensor first.
  4. Install the new upstream sensor and torque it to the manufacturer's specification (usually around 30 ft-lbs).
  5. Repeat for the downstream sensor.

3. Inspect and Clean Catalytic Converter

• Tools Required: Catalytic converter cleaner, wire brush, safety goggles.
• Sub-steps:
  1. Remove the catalytic converter from the exhaust system (unbolt if necessary).
  2. Inspect for physical damage or severe clogging.
  3. Use a wire brush to gently clean any residue on the exterior.
  4. If heavily clogged, consider replacing the catalytic converter with a new or refurbished unit.

4. Reinstall Components

• Tools Required: Ratchet, torque wrench.
• Sub-steps:
  1. Reinstall the catalytic converter and ensure all bolts are torqued to specification.
  2. Reconnect oxygen sensor plugs.
  3. Reconnect the negative battery terminal.

5. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• Sub-steps:
  1. Use the OBD-II scanner to clear the P0420 code from the system.
  2. Perform a test drive to monitor for any reoccurring codes or symptoms.