how to fix P0420 catalyst efficiency code on Toyota Corolla E170 (2013-2019)

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench
• Remove the upstream (pre-catalytic converter) oxygen sensor:
  1. Disconnect the sensor's electrical connector.
  2. Use the O2 sensor socket to unscrew the sensor from the exhaust pipe.
  3. Install the new oxygen sensor and torque it to the manufacturer's specification (usually around 30 lb-ft).
  4. Reconnect the electrical connector.
• Repeat the process for the downstream (post-catalytic converter) oxygen sensor if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, wrench set, cutting tool (if needed), torque wrench
• Remove the old catalytic converter:
  1. Disconnect the exhaust pipes connected to the catalytic converter (may require cutting if corroded).
  2. Unbolt the catalytic converter from the exhaust manifold and the exhaust system.
  3. Carefully remove the catalytic converter from its mounting.
• Install the new catalytic converter:
  1. Position the new catalytic converter and align it with the exhaust manifold and exhaust system.
  2. Secure it with bolts and torque them to the manufacturer's specifications.
  3. Reconnect any exhaust pipes and ensure all connections are tight.

4. Final Checks

• Reconnect the battery terminal.
• Start the vehicle and allow it to reach operating temperature.
• Perform a test drive to ensure the check engine light does not reappear.