what is causing the P0420 code on my Toyota Tacoma N300 (2016-Present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to prevent any electrical issues during the repair.
• Allow the exhaust system to cool before working on it.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, multimeter.
• If either the upstream or downstream oxygen sensor is faulty:
  1. Locate the oxygen sensors based on your vehicle's service manual.
  2. Disconnect the electrical connector from the sensor.
  3. Use the O2 sensor socket to remove the faulty sensor from the exhaust system.
  4. Install the new oxygen sensor and reconnect the electrical connector.
  5. Torque the new sensor to the manufacturer’s specifications (usually around 30 ft-lbs).

3. Inspect and Replace Catalytic Converter

• Tools Required: Wrench set, jack and jack stands, exhaust gasket, penetrating oil.
• If the catalytic converter is confirmed to be faulty:
  1. Raise the vehicle securely on jack stands.
  2. Apply penetrating oil to the exhaust bolts to facilitate easier removal.
  3. Remove the exhaust system components connected to the catalytic converter, noting their arrangement for reassembly.
  4. Remove the old catalytic converter and clean any remaining gasket material from the mating surfaces.
  5. Install the new catalytic converter with a new gasket, ensuring all bolts are tightened to the specified torque (usually around 25 ft-lbs).
  6. Reassemble the exhaust components in the reverse order of removal.