how to fix P0420 code in Toyota Highlander XU70 (2020-Present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace Oxygen Sensors (if faulty)

1. Locate the Oxygen Sensors:
   • Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
2. Remove the Oxygen Sensors:
   • Use an oxygen sensor socket to unscrew the sensors from the exhaust pipes.
   • Carefully disconnect the electrical connectors.
3. Install New Oxygen Sensors:
   • Apply anti-seize compound to the threads of the new sensors.
   • Install the new sensors by screwing them into place and reconnecting the electrical connectors.
   • Torque specification: typically around 30 ft-lbs (check manufacturer’s specifications).

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove Exhaust Components:
   • If the catalytic converter is damaged, remove any surrounding exhaust components as needed, using a socket set.
2. Unbolt the Catalytic Converter:
   • Carefully unbolt the catalytic converter from the exhaust manifold and exhaust pipe.
3. Install New Catalytic Converter:
   • Position the new catalytic converter in place and bolt it securely.
   • Torque specification: typically around 40 ft-lbs (check manufacturer’s specifications).
4. Reconnect All Exhaust Components:
   • Reassemble any exhaust components that were removed.

4. Clear Codes and Test

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