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

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to ensure safety.
• Allow the engine to cool before proceeding.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the pre-catalytic and post-catalytic oxygen sensors.
  2. Disconnect the electrical connectors from each sensor.
  3. Use an O2 sensor socket or wrench to remove the sensors from the exhaust manifold and catalytic converter.
  4. Install new oxygen sensors, ensuring they are torqued to the manufacturer specifications (usually around 30 lb-ft).
  5. Reconnect the electrical connectors.

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

• Sub-steps:
  1. Locate the catalytic converter in the exhaust system.
  2. Inspect for physical damage or clogging (check for rattling sounds when shaken).
  3. If damaged, unbolt the catalytic converter from the exhaust flanges (typically requires a socket set).
  4. Install the new catalytic converter, ensuring to use new gaskets.
  5. Torque the bolts to the specified value (consult repair manual, usually around 40 lb-ft).

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 monitor performance and check if the check engine light reappears.