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

Solution

1. Preparation

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

2. Inspect Oxygen Sensors

• Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
• Using a socket wrench, carefully remove the oxygen sensors.
• Inspect the sensors for damage or contamination; replace if necessary.
• Reinstall the sensors and torque to manufacturer specifications (usually around 30 ft-lbs).

3. Replace the Catalytic Converter (if necessary)

• Remove the exhaust heat shield to access the catalytic converter.
• Using a socket set, detach the bolts connecting the catalytic converter to the exhaust manifold and exhaust pipe.
• Carefully remove the catalytic converter from its mounting.
• Install the new catalytic converter, ensuring proper alignment.
• Torque the bolts to manufacturer specifications (typically between 30-40 ft-lbs, depending on the model).
• Reinstall the heat shield.

4. Reconnect Battery and Clear Codes

• Reconnect the battery terminals and ensure they are tight.
• Use an OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Start the engine and allow it to reach operating temperature.