how to address the P0420 code on my Toyota Highlander XU70 (2020-Present)?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Safety gear: gloves and goggles.
• Disconnect the battery to prevent electrical shocks.

2. Inspect and Replace Oxygen Sensors

1. Locate the upstream (pre-catalytic) and downstream (post-catalytic) oxygen sensors.
2. Using a socket wrench, carefully remove the oxygen sensors.
3. Inspect the connectors and wiring for any damage or corrosion.
4. Replace the sensors if they show signs of wear or malfunction.
5. Apply anti-seize compound on the threads of the new sensors before installation.
6. Install the new sensors and torque them to manufacturer specifications (typically around 30 ft-lbs).

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

1. Examine the catalytic converter for any signs of physical damage or blockage.
2. If damaged, use a wrench to remove the bolts securing the catalytic converter to the exhaust system.
3. Carefully detach the catalytic converter and replace it with a new one, ensuring proper alignment.
4. Torque the bolts to manufacturer specifications (usually around 30-40 ft-lbs).
5. Reconnect any exhaust hangers or brackets as needed.

4. Clear Codes and Test

1. Reconnect the battery.
2. Use an OBD-II scanner to clear the P0420 code from the system.
3. Start the engine and let it idle for a few minutes to ensure proper operation.
4. Take the vehicle for a test drive under various conditions to confirm that the check engine light does not reappear.