how to fix P0420 code in Toyota Highlander Fourth Generation (2020-present)

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the negative battery terminal to prevent any electrical shorts.
• Allow the exhaust system to cool down before beginning work.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor by unscrewing it from the exhaust manifold.
• Inspect the sensor for damage; if faulty, replace it with a new compatible oxygen sensor.
• Torque the new sensor to the manufacturer's specification (typically around 30 lb-ft).
• Repeat the process for the downstream oxygen sensor if necessary.

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter (if needed), gasket scraper
• Remove any heat shields or brackets securing the catalytic converter.
• Disconnect the exhaust pipes connected to the catalytic converter (cut if necessary).
• Remove the old catalytic converter and clean the mounting surfaces.
• Install the new catalytic converter, ensuring that any gaskets are replaced.
• Secure the exhaust system components, properly torquing bolts to specifications.

4. Clearing the Code

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code from the vehicle's system.
• Start the engine and allow it to reach operating temperature.