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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the vehicle to cool down before starting work on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream (pre-catalytic converter) oxygen sensor:
  • Use an O2 sensor socket to unscrew the sensor.
  • Inspect the threads for damage and clean the sensor port.
• Install the new upstream oxygen sensor:
  • Apply anti-seize compound on the threads of the new sensor.
  • Torque to the manufacturer's specifications (typically around 30 lb-ft).
• Repeat the process for the downstream (post-catalytic converter) oxygen sensor if it is faulty.

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket.
• Remove the catalytic converter:
  • Disconnect the exhaust pipes from the catalytic converter using the socket set.
  • Remove any brackets or heat shields that are obstructing access.
• Inspect the old catalytic converter for damage and clogging.
• Install the new catalytic converter:
  • Position the new converter and reconnect the exhaust pipes.
  • Ensure all bolts are tightened to the specified torque (typically between 30-50 lb-ft).
  • Replace any gaskets as necessary to prevent exhaust leaks.

4. Reconnect Battery and Test

• Reconnect the negative battery terminal.
• Start the vehicle and allow it to reach operating temperature.
• Monitor the exhaust for any unusual sounds or leaks.