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

Solution

1. Preparation

• Gather tools, including an OBD-II scanner, socket set, torque wrench, and safety gear.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors (if necessary)

• Sub-steps:
  1. Disconnect the negative battery terminal to prevent electrical shorts.
  2. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
  3. Unplug the electrical connectors from both sensors.
  4. Use an O2 sensor socket to carefully remove the sensors from the exhaust system.
  5. Install the new oxygen sensors by threading them in and tightening them to manufacturer specifications (usually around 30 ft-lbs).
  6. Reconnect the electrical connectors to the sensors.

3. Inspect and Replace Catalytic Converter (if necessary)

• Sub-steps:
  1. Raise the vehicle securely using jack stands.
  2. Inspect the catalytic converter for any physical damage or signs of clogging.
  3. If replacement is necessary, remove the exhaust pipes connected to the catalytic converter using the appropriate socket set.
  4. Unbolt and remove the catalytic converter from the vehicle.
  5. Install the new catalytic converter and ensure all bolts are tightened to manufacturer specifications.
  6. Reconnect the exhaust pipes and check for proper alignment.

4. Clear Codes and Test Drive

• Sub-steps:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Start the engine and allow it to reach operating temperature.
  4. Take the vehicle for a test drive to ensure that the check engine light does not reappear.