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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the exhaust system to cool before working on it to avoid burns.

2. Inspect and Replace Oxygen Sensors

1. Remove the upstream oxygen sensor:
   • Use an oxygen sensor socket and ratchet to unscrew the sensor from the exhaust manifold.
2. Install the new upstream oxygen sensor:
   • Apply anti-seize compound to the threads of the new sensor and thread it into place.
   • Torque the sensor to manufacturer specifications (typically around 30 lb-ft).
3. Repeat for the downstream oxygen sensor if diagnostic steps indicated a fault.

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

1. Remove the exhaust components:
   • Use a socket set to unbolt the catalytic converter from the exhaust system.
   • Carefully lower the exhaust components to avoid damaging the exhaust hangers.
2. Install the new catalytic converter:
   • Ensure the new unit is compatible with your model.
   • Bolt the new catalytic converter into place and torque the bolts to the specified value (typically around 30 lb-ft).
3. Reattach any exhaust components removed during the process.

4. Final Checks

• Reconnect the negative battery terminal.
• Clear the codes using the OBD-II scanner.
• Start the engine and allow it to reach operating temperature.