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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on the vehicle.
• Allow the exhaust system to cool before inspection.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, ratchet, torque wrench.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for contamination or damage; replace them if they are faulty.
• Install new sensors and torque them to manufacturer specifications (usually around 30 ft-lbs).

3. Inspect and Replace the Catalytic Converter

• Tools Required: Socket set, exhaust pipe cutter, gasket scraper, high-temperature exhaust sealant.
• Remove any exhaust components connected to the catalytic converter (e.g., heat shields, brackets).
• Use an exhaust pipe cutter to remove the old catalytic converter, being careful not to damage surrounding pipes.
• Clean mating surfaces of the exhaust pipes using a gasket scraper to ensure a proper seal.
• Install the new catalytic converter, ensuring it is oriented correctly and secure.
• Use high-temperature exhaust sealant on joints as needed and reattach any removed components.

4. Clear Codes and Test Drive

• Reconnect the battery and use an OBD-II scanner to clear the P0420 code.
• Start the engine and allow it to reach operating temperature.
• Take the vehicle for a test drive to monitor for any reoccurrence of the P0420 code.