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

Solution

1. Preparation

• Gather tools and parts needed for repairs.
• Disconnect the vehicle battery to ensure safety during the repair process.
• Allow the engine to cool down before working on the exhaust system.

2. Inspect and Replace Oxygen Sensors

• Tools Required: O2 sensor socket, wrench set, torque wrench.
• Remove the upstream and downstream oxygen sensors using the O2 sensor socket.
• Inspect the sensors for contamination or damage.
• If faulty, replace them with new OEM or equivalent sensors.
• Torque the new sensors to the manufacturer's specifications (usually around 30 lb-ft).

3. Inspect and Replace Catalytic Converter

• Tools Required: Socket set, torque wrench, exhaust gasket.
• Remove any heat shields if necessary by unbolting them.
• Disconnect the exhaust pipe from the catalytic converter using the socket set.
• Remove the catalytic converter from its mounting location.
• Install the new catalytic converter, ensuring that any gaskets are replaced.
• Torque the bolts to the manufacturer's specifications (usually around 40 lb-ft).

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 ensure the issue is resolved and monitor for any new codes.