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

Solution

1. Preparation

• Gather 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. Inspect and Replace Oxygen Sensors

1. Locate the oxygen sensors:
   • The pre-catalytic converter sensor is usually located on the exhaust manifold, while the post-catalytic converter sensor is located further down the exhaust pipe.
2. Remove the old sensors:
   • Use an oxygen sensor socket to carefully unscrew the sensors from their respective positions.
3. Install the new sensors:
   • Apply anti-seize compound to the threads of the new sensors (if applicable).
   • Hand-tighten the sensors, then use a torque wrench to tighten to the manufacturer’s specifications (typically around 30 lb-ft).
4. Reconnect wiring harness:
   • Ensure the connectors are secure.

3. Inspect and Replace Catalytic Converter (if necessary)

1. Remove the catalytic converter:
   • Loosen and remove the bolts or clamps securing the catalytic converter to the exhaust system using a socket set.
   • Carefully detach the converter from the exhaust pipe and the exhaust manifold.
2. Inspect the old catalytic converter:
   • Check for signs of damage, such as cracks or collapse.
3. Install the new catalytic converter:
   • Position the new catalytic converter in place and secure it using the original bolts or clamps.
   • Tighten to the manufacturer’s specifications (usually 25 lb-ft for bolts).
4. Reconnect any exhaust hangers or sensors:
   • Ensure everything is secure and correctly positioned.

4. Clear Codes and Test Drive

1. Reconnect the battery:
   • Ensure all connections are tight.
2. Clear the trouble codes:
   • Use the OBD-II scanner to erase the P0420 code.
3. Test drive the vehicle:
   • Drive the vehicle under various conditions to allow the ECM to monitor the catalytic converter's performance.