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

Solution

1. Preparation

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

2. Inspect and Replace Oxygen Sensors

1. Locate the pre-catalytic and post-catalytic oxygen sensors.
2. Use a socket wrench to carefully remove the sensors from their respective locations.
3. Inspect the sensors for signs of wear or damage (e.g., contamination or broken wires).
4. If faulty, replace them with new OEM or high-quality aftermarket sensors.
5. Torque new sensors to the manufacturer’s specifications (typically around 30-40 lb-ft).

3. Inspect and Replace Catalytic Converter

1. If the oxygen sensors are functioning correctly, inspect the catalytic converter for blockages or damage.
2. Remove any heat shields covering the catalytic converter.
3. Disconnect the exhaust pipes from the catalytic converter using a socket set.
4. Remove the catalytic converter from its mounting points.
5. Install the new catalytic converter, ensuring it fits securely.
6. Torque all connections to the manufacturer's specifications.

4. Reconnect Battery and Clear Codes

1. Reconnect the negative battery terminal securely.
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, checking for leaks and proper operation.