how to fix the P0420 code on my Toyota Camry XV50 (2012-2017) for good?

Solution

1. Preparation

• Gather tools and parts required for the repair.
• Disconnect the battery to prevent electrical shorts.
• Raise the vehicle securely on jack stands to access the exhaust system.

2. Inspect and Clean Oxygen Sensors

• Tools Required: O2 sensor socket, cleaner for electrical connections.
• Remove the downstream oxygen sensor using the O2 sensor socket.
• Clean the sensor connector and check for corrosion.
• Inspect the sensor for damage; replace if necessary.

3. Replace Catalytic Converter

• Parts Required: New catalytic converter, gaskets, and bolts.
• Remove the exhaust pipes connected to the catalytic converter by loosening the bolts.
• Remove the old catalytic converter, ensuring to clean the mating surfaces.
• Install the new catalytic converter with new gaskets and torque the bolts to the manufacturer's specification (typically around 30-40 lb-ft).
• Reconnect any sensors or components that were disconnected.

4. Reinstall Oxygen Sensors

• Reinstall the cleaned or new downstream oxygen sensor.
• Torque the sensor to manufacturer specifications (usually around 30 lb-ft).
• Reconnect the vehicle's battery.

5. Clear Codes and Test Drive

• Use the OBD-II scanner to clear the P0420 code.
• Test drive the vehicle under various conditions to ensure the check engine light does not reappear.