how to fix P0420 code on my Toyota Highlander Third Generation (2014-2019)?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to avoid electrical shorts.
• Ensure the vehicle is on a level surface and secure it with wheel chocks.

2. Inspect and Replace Oxygen Sensors (if necessary)

1. Locate the Oxygen Sensors: Identify the upstream and downstream oxygen sensors in the exhaust system.
2. Remove the Sensors:
   • Use an oxygen sensor socket to unscrew the sensors from the exhaust pipe.
   • Disconnect the wiring harness from each sensor.
3. Install New Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors and connect the wiring harness, ensuring a secure fit.

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

1. Remove Exhaust Components:
   • Use a socket set to unbolt the exhaust pipe sections connected to the catalytic converter.
   • Support the exhaust system with jack stands if necessary.
2. Remove the Catalytic Converter:
   • Unbolt the catalytic converter from its mounting points.
   • Carefully remove the catalytic converter from the vehicle.
3. Install New Catalytic Converter:
   • Position the new catalytic converter in place.
   • Secure it with bolts and ensure proper alignment.
   • Reattach any exhaust sections previously removed.

4. Clear Codes and Test Drive

1. Reconnect Battery: Reconnect the battery terminals securely.
2. Clear Error Codes: Use the OBD-II scanner to clear the P0420 code from the ECM.
3. Test Drive: Drive the vehicle for a short distance to monitor performance and ensure the check engine light remains off.