how to fix P0420 code on my 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 avoid any electrical issues.

2. Inspect and Clean Oxygen Sensors

• Tools Required: O2 sensor socket, multimeter, penetrating oil.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for carbon buildup and clean them with a suitable sensor-safe cleaner if necessary.
• If damaged or faulty, replace the oxygen sensors with OEM parts.

3. Replace Catalytic Converter (if necessary)

• Tools Required: Socket set, torque wrench, exhaust pipe cutter (if needed), new gaskets.
• Locate the catalytic converter and remove the bolts securing it to the exhaust system using the socket set.
• If the converter is welded in place, use the exhaust pipe cutter to remove it carefully.
• Install the new catalytic converter, ensuring proper alignment with the exhaust system.
• Torque the bolts to the manufacturer's specifications (usually around 30-40 lb-ft, check the service manual for specifics).

4. Reconnect Battery and Clear Codes

• Reconnect the battery and use the OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to idle for a few minutes.