how to fix the P0420 engine code on my Toyota Tacoma N300 (2016-Present)

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, torque wrench, penetrating oil.
• If oxygen sensors are faulty:
  1. Locate upstream (pre-catalytic) and downstream (post-catalytic) O2 sensors.
  2. Apply penetrating oil to the sensor threads and allow it to soak.
  3. Disconnect the electrical connectors from the sensors.
  4. Use the O2 sensor socket to remove the sensors.
  5. Install new sensors, tightening to manufacturer specifications (usually around 30 lb-ft).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, torque wrench, gasket scraper.
• If the catalytic converter is damaged:
  1. Remove the exhaust pipe bolts connecting to the catalytic converter, noting the positioning of any gaskets.
  2. Carefully remove the old catalytic converter.
  3. Clean the mating surfaces on the exhaust pipe and the manifold.
  4. Install the new catalytic converter using new gaskets, tightening bolts to manufacturer specifications.

4. Clear Codes and Test Drive

• Tools Required: OBD-II scanner.
• After repairs:
  1. Reconnect the negative battery terminal.
  2. Use the OBD-II scanner to clear the P0420 code.
  3. Test drive the vehicle under various conditions (highway, city) for at least 20 minutes to ensure the code does not reappear.