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

Solution

1. Preparation

• Gather all necessary tools and parts.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Oxygen Sensor Replacement

1. Remove the Engine Cover (if applicable)
   • Use a socket set to remove any bolts securing the engine cover.
2. Locate the Oxygen Sensors
   • Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
3. Disconnect the Oxygen Sensor Wiring
   • Carefully unplug the connectors from the oxygen sensors.
4. Remove the Oxygen Sensors
   • Use an oxygen sensor socket or wrench to carefully unscrew the sensors from the exhaust manifold and catalytic converter.
5. Install New Oxygen Sensors
   • Apply anti-seize compound on the threads of the new sensors.
   • Screw in the new sensors by hand to avoid cross-threading, and tighten to manufacturer specifications (typically around 30 ft-lbs).
6. Reconnect the Wiring
   • Plug the connectors back onto the new oxygen sensors.

3. Catalytic Converter Inspection and Replacement (if needed)

1. Inspect the Catalytic Converter
   • Look for signs of physical damage, rattling sounds, or excessive heat.
2. Remove the Exhaust Components
   • If replacement is necessary, unbolt the exhaust piping connecting to the catalytic converter using a socket set.
3. Remove the Old Catalytic Converter
   • Carefully detach the catalytic converter from the exhaust system.
4. Install the New Catalytic Converter
   • Position the new catalytic converter and secure it to the exhaust system, ensuring proper alignment.
5. Reinstall Exhaust Components
   • Tighten all bolts to manufacturer specifications to prevent leaks.

4. Final Steps

1. Reconnect the Battery
   • Reattach the negative battery terminal.
2. Clear the Codes
   • Use the OBD-II scanner to clear the P0420 code from the ECU.
3. Test Drive the Vehicle
   • Drive the vehicle under various conditions to ensure the check engine light does not reappear.