what does it mean if my Toyota Highlander Fourth Generation (2020-present) has a P0420 code

Solution

1. Preparation

• Gather all 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

• Tools Required: O2 sensor socket, ratchet, torque wrench
• Remove the upstream oxygen sensor (before the catalytic converter) using the O2 sensor socket.
• Inspect the sensor for damage; if faulty, replace with a new sensor.
• Reinstall the new sensor and torque to manufacturer specifications (approximately 30 ft-lbs).
• Repeat for the downstream oxygen sensor (after the catalytic converter) if necessary.

3. Check and Replace Catalytic Converter (if required)

• Tools Required: Socket set, jack and jack stands, exhaust gasket (if applicable)
• Safely lift the vehicle using a jack and secure it with jack stands.
• Remove any bolts or clamps securing the catalytic converter to the exhaust system.
• Carefully detach the catalytic converter from the exhaust pipes.
• Inspect the old catalytic converter for damage or clogging.
• Install the new catalytic converter and tighten all bolts to the manufacturer's torque specifications (typically around 30-40 ft-lbs).
• Replace any exhaust gaskets as necessary to prevent leaks.

4. Reconnect Battery and Clear Codes

• Reconnect the negative battery terminal.
• Use the OBD-II scanner to clear the P0420 code and any other stored codes.
• Start the engine and allow it to reach operating temperature.